The different processes that damage DNA have sequence preferences for the direct change in the DNA (e.g. G-->C versus G-->T), as well as the sequence around the damage. Smoking causes very very different signatures of DNA damage than, say, damage from UV from being in the sun.
So every cell in our body carries with it a (noisy) history of the mutagenic processes it has been exposed to.
This paper found some differences in these mutational signatures of later colon cancers, and attributed them to colibactin, a mutagen produced by bacteria.
It remains to be seen what percentage of the increase in under-50 colon cancers this would explain, but it's an additional risk factor that didn't make it onto the chart, likely because it's not coming from standard epidemiological analysis, and instead from the world of molecular analysis.
Wow, I had no idea there is a 15X increase for endurance athletes. Make me want to dial down the running a bit, which make you wonder where the sweet spot is for distance training.
I wonder if it's due to diet. Endurance athletes love their simple carbs, highly processed gels. I've seen plenty of cyclists taking gummy bears on rides for fuel, or a concoction that is effectively sugar water to drink
The study referenced is really light on details and they don't say if they controlled for that
It's rare but can happen where long distance running causes ischemic colitis which is where on a long run enough blood is diverted from the large intestine that it damages the intestine long term. It isn't surprising to me that there's higher likelihood of colon cancer given this. It seems like repeated bouts of lower blood for the intestine on long runs has a cumulative impact and damages the colon even if it doesn't cause ischemic colitis.
This theory has been put forward, but it's important to point out that there is no real evidence yet. An alternative theory is diet, which is also the leading theory for increasing incidences in non-athletes. Highly processed, calorie dense foods have been on the watchlist for a while, and ultra endurance athletes have a special need for these to satisfy their caloric requirements. It could also be a combination of these factors or something else that was missed entirely so far.
Interesting, I wasn't aware of that connection either. I was diagnosed with stage IV colon cancer, but was identified as 'genetic' and not caused by diet or lifestyle. I used to be a heavy runner too, done a few marathons, and plenty more 10k, 8ks etc. Wonder if that could be a correlation... Treatments have it contained/in maintenance so at least I have that going for me.
Ah, that definitely wasn't offered to me as an option. Glad to see the progress however. It would be nice if there was an alternative test so that I could tell my kids it's not genetic.
I have an ultra-runner friend who just got diagnosed with stage 4 colon cancer. Absolutely devastating. He had a colonoscopy just a few years ago. His only symptom was not feeling well after a long race.
It may be the damage of repetitive motion, it may be chemicals released into the bloodstream from endurance athletics. It may be something else. Without knowing the root cause, it's impossible to figure out the "sweet spot"
Could be a lot of things. Lots of long distance runners consume a lot of sugary gels to keep going. Not sure what the typical composition is, but likely lots of glucose and no fibre.
The marathon runners I know also seem to eat tons of junk food, they can get away with it from a weight perspective because a long run will burn it off, but it could have other consequences.
Point being: there's a lot about long distance runners that's quite different from other people.
But the rates of obese people who presumably consume a lot of sugars and carbs are 1/10th the rate of ultra marathon runners. It's scary to think that such conditioned athletes could be subject to this horrible disease.
i saw something recently that pointed to the fact that ultra runners end up with less blood in their guts while running for SO long its leading to cancers and such.
>2x ultra-marathons >26 miles, or at least 5 marathons completed
Yes, and it seems like it's really a 7.5x risk increase. Still pretty spectacular, though!
I really wonder what could cause that. Randomly throwing out possible causes: 1) blood redirected away from gut, 2) overuse of NSAIDS, 3) ultraprocessed foods (gels etc), 4) strange microbiome issues (gels + stress in gut from extreme exertion = altered gut flora?)
The study that found the result is DOI: 10.1200/JCO.2025.43.16_suppl.3619
Which is way more than what original hunters and gatherers ever clock. They do move a lot, but not so much, and they alternate their activities a lot too (running, walking, resting, taking entire days off and just guarding their village).
We're not really optimized for this sort of extreme endurance and long-term development of serious pathologies is unsuprising.
You shouldn't so offhandedly assume a hunter-gatherer lifestyle couldn't lead to issues like increased risk of CRC, or that activities which lead to increased risk of CRC couldn't be what hunter-gatherers did. Evolution is neither fast nor perfectly precise. Plenty of animal populations have common health problems that simply weren't harmful enough to reproduction to be selected out, much less something rare and late-onset like CRC.
I don't assume anything. From what we know about health of the last surviving hunter-gatherers, they suffer significantly less from "diseases of civilization" when taken in proportion to their settled neighbours. Some of those diseases (such as high blood pressure or diabetes 2nd type) seem to be totally absent in them. Cancers do happen, but not as often.
This pattern is quite old. Already ancient Egyptians suffered from civilizational diseases much more than hunter-gatherers, especially the richer ones (heart attacks, gout, cancer).
I won't bother checking or disputing the accuracy of your factual claims, because it does not matter.
Colorectal cancer is not the same thing as high blood pressure, or type 2 diabetes, or any other cancer that isn't colorectal cancer. Diseases are not a monolith and you cannot assume low risk of some diseases means low risk of others. That is wild guesswork passed off as logic, like measuring the shadow your testicles cast on the wall and announcing it is 24.1 degrees Celsius. Ultra-marathon runners also have low risk of type 2 diabetes!
Do you have specific evidence that modern hunter-gatherers have low rates of colorectal cancer that cannot be explained by survivorship bias, screening, genetic differences, and all other confounders, and that they are representative of historical hunter-gatherers? No? Then you cannot confidently conclude that hunter-gatherers didn't experience elevated rates of CRC.
Absolutely, we may have a depressed rate of CRC where ultramarathoners just get back up to the historical baseline. Who knows, but we don’t know it isn’t that.
"Diseases are not a monolith and you cannot assume low risk of some diseases means low risk of others. That is wild guesswork passed off as logic..."
Diseases are not a monolith, but they do tend to arise and fall in some specific clusters, and that is not "logic", good or bad (too many computer-minded people drag logic into the chaos that is biology), but rather a long-time empirical observation, albeit with some exceptions.
You are really obsessed with my testicles. That is a weird comparison, but at least you know that you're not a bot. This would be too weird for a LLM to produce.
In general, I don't think your irony is as strong as you think. Shrinkage of various materials in the cold is the original basis for a thermometer.
Of course it is better to use something better-observable like mercury. But in absence of an industrial civilization, you don't have mercury to measure.
Sigh. Sure, if you had a gun to your head and you knew nothing else, it would be better to guess that a given population (hunter-gatherers) with low rates of some illnesses (T2D, HBP) also had low rates of another illness (CRC) than the reverse. Okay. That's a slightly better-than-chance guess, not anywhere near a solid basis for speculation.
"Anyways, it makes sense that marathoners get CRC because hunter-gatherers probably don't run that much" is bongcloud lalaland tier guesswork.
"makes sense that marathoners get CRC because hunter-gatherers probably don't run that much"
That is a misinterpretation of what I wrote. Let me reformulate.
"Marathons are so much more extreme than what we used to do in the Stone Age, that some pathologies resulting from such long-term physical overload are to be expected." I don't see anything lala about that. You do extreme things, you reap some consequences, sooner or later.
I would say that marathons go beyond our design parameters, but my experience in HN is that the "design" metaphor always conjures some people who consider it a dog-whistle for intelligent design (as opposed to evolution), not just an imprecise metaphor, as metaphors usually are. So I avoid it in order not to attract a senseless fight.
I’m in my early 30s and am starting to think about getting a screening. Problem is, it’s not trivial to do. You have to really upsell your doctor to get one so early, even though it’s a relatively benign procedure.
There is a noninvasive testing method called Shield but it is way too flawed to be reliable (with poor positive rates for malignant tumors)
Not completely. Every once in a while they accidentally puncture the intestine with the probes and that becomes a significant medial problem. It doesn't happen often, but that is still a risk that doctors need to consider. If you are over 50 getting one every 10 years is a good idea, and there is some consideration if younger might be worth it. However so few people get colon cancer under 40 that it isn't worth the risks for most - but if there are other signs of a problem (either family history or symptoms) that changes things and it may be worth it.
I was diagnosed at 35 seven years ago with no history. Getting a colonoscopy never crossed my mind, much less being suggested by my general practitioner.
The trigger for me was blood in my stool. It was the slightest amount but I pursued it because that didn’t seem right. Turns out I had hemorrhoids which brought up something I feel hits others - I was embarrassed.
Fortunately the doctor that performed a banding procedure pushed me to get a colonoscopy purely out of being through and seeing the number of incidences increase at my age range.
I often wonder how much the embarrassment factor comes into play here.
Blood in the stool, at age 41. Benign but a VERY large polyp so I have a followup soon. If you have an instinct to get tested, especially if you have any evidence, do it. My doc fought me to NOT get tested but I persisted. The embarrassment factor is a thing, but we have to get over it!
Was it a consistent blood in stools or just a one time thing? I've had what I think that is once or twice and then take the approach to just see if it recoccurs a second time before going to a doctor, not sure if that's the correct approach or if a single instance should be alarming enough.
For me it was small amount consistently.
But I cannot stress enough that it was the diagnosis of hemorrhoids coupled with a very proactive doctor that led to me being diagnosed with cancer. It was a lucky circumstance that it was staged early because the additionally suggested screening was not standard protocol for my age.
If you have any abnormalities in your bowel movements (blood, ribboning, etc.) and you have the ability to get it checked then it could offer peace of mind. And yes, there are small chances of intestinal perforations with a colonoscopy.
For a screening procedure recommended as a mass conducted preventative measure in otherwise healthy people, harms must be regulated to a better standard than "doesn't happen often". The study that I read of was about serious issue occuring something like one in 120 procedures. It was done at Kaiser. Next time you're enjoying a sausage, take a moment to look at the sausage skins. If I understand correctly, our intestinal walls are quite thin, and even the colon vulnerable.
If you tell your doctor that a parent had polyps removed (say, recently), that will give you your best chance of getting one. Most likely, if you're in an even remotely progressive area, your doc wants you to have one, but their hands are tied by the insurance company. Afaik you dont have to provide any proof of your claim re parental polyps.
> but their hands are tied by the insurance company.
Doctors' ability to prescribe or refer is never restricted by an insurance company. If they think a patient should get whatever healthcare, they are free to say it.
Is the intended meaning that health insurance should pay for anything and everything? Even systems where the government pays directly like the UK have parameters under which the government will pay for a procedure or medicine.
Not at all. Patients are free to pay out of pocket for procedures not covered by insurance. An extra colonoscopy (one not classified as medically necessary), while expensive, is within the financial means of most middle-class adults.
In CA, my doctor can refer me to get a Cologuard. But it's private pay, and they want payment up front since isurance companies don't restrict doctor's ability, only reimbursement.
So they may not be willing (even though they are able) perform procedure/test if they aren't confident they'll get paid.
> I’m in my early 30s and am starting to think about getting a screening.
This is a pretty stupid thing to do unless you've had some sort of symptom or family history. Your protection from illness due to screening is statistical, and jumping out of the calculated recommendation just makes it more likely to hurt you (false positives, false negatives, injuries from the procedure) than to benefit you.
Desperately trying to fabricate a reason is just intentionally trying to hurt yourself.
I'm not against colonoscopies (is anyone?) and I personally had my first one early because of an odd pain. Turned out to be unrelated.
edit: the neurotic desperation for disease screening that I see in a lot of people bothers me a lot because it's this odd fetishization of medical science combined with the active subversion of it. For me it's a weird insistence that all tests are good but that the math behind them is not.
From a 'public health' perspective, it makes perfect sense to limit the frequency of screening procedures by age and other broad risk-factors, but that doesn't help at the individual level if you fall on the unlucky side of those statistics.
Most cancers are still very much lethal once they progress to a certain point, and the best treatment we know of is early detection. Many of the cancer screens are harmless or don't add significant risk of death, so it really comes down to money and medical resource availability (also solved with money.)
I don't see much difference in someone paying out-of-pocket for a full-body MRI/colonoscopy vs. them spending way above average on any other item that slightly reduces the risk of dying (how many smoke alarms and fire extinguishers does your home have?)
Lie about family history, but even colonoscopies are not perfect; I just had somebody in my family die of CRC because...
- They had symptoms and wanted a screening, but their PCP repeatedly denied them a referral for like a year because they were "too young".
- They lied about family history after symptoms got worse and got their referral.
- They got the colonoscopy which came back clean, and then symptoms continued to get worse.
- Finally their doctor gave them a referral for an MRI.
Results were stage 4 CRC. The doctor performing the colonoscopy missed the tumor, which was tucked into the sigmoid (the bend in your colon), where he didn't properly inflate because he wasn't taking it very seriously. It had a thumb-tip sized protrusion inside the colon but had gotten huge on the opposite side of the colon wall. They fought it for 8 years after the diagnosis and over 100 rounds of chemo (!!!), were about to get a new procedure at Yale, in which the doctor told them to think of it in terms of "this really may be a complete cure", but it was canceled because of the Big Beautiful Bill.
If you have symptoms (even if you don't), don't let some fuckass Nurse Practitioner tell you no. They don't know shit and they let their egos get in the way when they have to deal with moderately informed patients advocating for themselves. This was preventable and tge medicap system failed them because both the PCP and the doctor performing the colonoscopy were not paying attention to what they were being presented with and saw only their own expectations.
Also...apparently doctors wanted to lower the screening age to like 35, but insurance companies fought it, so it's at 45.
>Also...apparently doctors wanted to lower the screening age to like 35, but insurance companies fought it, so it's at 45.
On this website, it is frequently opined that because health insurers have a legal minimum medical loss ratio, that health insurers prefer inflated costs so that their medical losses are higher, which means their premiums can be higher, which means their revenue is higher, which means their profit is higher.
I would have thought health insurers would support a lower screening age, especially since it would inflate costs for all insurers so everyone's cut of the now bigger pie gets bigger.
I'm a little removed from the situation, (not my nuclear family) but I believe the statute is up. It's too difficult to litigate in, say, the first two years of your stage 4 diagnosis before the law won't allow a suit.
I've decided to invest $2000/year and get an MRI scan every year. My first one, the baseline, showed nothing remarkable, thank God. I'm scheduled for my second one in a few weeks, I want to be able to catch anything weird very early on. I think it's worth it despite what all the know-it-alls say.
while it sucks, paying for it out of pocket is probably cheaper if you can't get it covered. In the long run, $1500 as a bridge until your 40s feels cheaper than stage 4 cancer.
$1500? That sounds optimistic. I'm getting an upper endoscopy tomorrow and they've already told me it will be $4K. The equipment is similar, I expect colonoscopy is not cheaper.
The encouragement is that the rate of "death from colorectal carcinoma" seems to be reduced in studies of screening. This is a 'disease specific' mortality statistic. Most of us don't care why we die, or what is ultimately written upon our death certificates, we would simply rather still be alive! So reduction in "total mortality" would be a more convincing endpoint. If a study of some screening test for a dread disease does NOT show a reduction in the 'total mortality' of the group screened at some clinically reasonable point of time in the future, one could argue that the screening was pointless. Yes, perhaps less people died from the condition being screened for, but if the same number of persons died in the screened -vs- unscreened group, what has been accomplished?
It has been hard, well impossible, to show that screening for colorectal cancer reduces the total or overall death rate. For example, a recent study published in the NEJM in 2022 did find a reduction in persons who died from colorectal carcinoma after screening with colonoscopy. But they did NOT find that the total or overall death rate had decreased!
"The risk of death from any cause was 11.03% in the invited group and 11.04% in the usual-care group (risk ratio, 0.99; 95% CI, 0.96 to 1.04)." N Engl J Med 2022;387:1547-1556 DOI: 10.1056/NEJMoa2208375V
When reading 'screening' studies, one usually needs to look very carefully at the article and published data to find this statistic. Sometimes it is not even reported at all, it is simply ignored. It's almost like the authors don't want the fact that the screening program does not reduce one's risk of dying to any measurable degree is ... embarrassing?
This problem is not unique to colorectal cancer screening.
When studies are designed a key parameter is the statistical power that the size of the stud provides: how big of a difference in the key stat can it find?
I would expect that the design of a study will be able to find differences in the key readout: did screening reduce death in the types of cancer it could find.
Colon cancer deaths are only a small fraction of total mortality, and statistically, finding a small change in a ratio close to zero is far easier to see than a that same change in a ratio that's further away from zero.
So I would not expect a study to be powered to be able to find changes in total mortality from all causes. That would take a far larger number of people and generally be considered a waste of resources that would be better spent investigating other things.
So I wouldn't take the lack of statistical significance in total mortality as evidence of anything, unless total mortality was a primary outcome that was being tested.
Pretty much all the good interventions for reducing mortality will not have much impact on total mortality because there are so many things causing total mortality. But add up all the small ones and it starts to make differences in total mortality.
Something I've never seen in these analyses is drinking. Millennials are heavy drinkers. Both craft brews and cocktails were defining generational traits. Not everyone is a drinker but it appears they are heavy drinkers compared to other generations.
The theory behind the ultra marathoners is that extreme distance running disrupts the epithelial layer and microbiome in the gut. Wouldn't drinking have similar effects?
It’s more like, millennials got older and started drinking less (as happens), and Gen Z drinks different things like hard seltzer, and also drinks a bit less overall. Plus there were just way too many craft brewers making hoppy ipa to begin with.
Unfortunately, hoppy IPA seems to constitute the majority of the survivors. I have no interest personally in suffering through another hazy sour grapefruit triple ipa, but that seems to be about 90% of craft brewery output these days.
Interesting, where I live in Brooklyn it seems this is no longer an issue. Tons of non-hoppy craft options like pilsners, stouts, lagers, etc at ~every craft brewery or gastropub.
I see one poll by a cannabis outlet claiming 46% of marijuana users are millenials (read: high proportion of user base). However, <20% of millennials smoke marijuana. [0] And another claims <40% use cannabis.
That's still below the ~50% of millennials who consume alcohol.
There's roughly 4 to 5 generations alive at any point and the middle generation is going to be considered both old and young by the generations surrounding it.
You're right. 8 year olds would call you ancient and 80 year olds would call you a baby. Middle age is relative and unless you're over 45 you don't admit to it, and then hold on to it for too long.
Well, your first Google result is a blog post that makes my point.
> For example, baby boomers are the generation with the most dramatic increase in harmful alcohol abuse. In contrast, Gen Z prefers the sober lifestyle as they are known to consume alcohol much less than any of their older counterparts, including millennials.
> Compared to non-/occasional drinking (≤1 g/day), light/moderate drinking (up to 2 drinks/day) was associated with a decreased risk of CRC (OR: 0.92, 95% CI: 0.88–0.98, p=0.005), heavy drinking (2–3 drinks/day) was not significantly associated with CRC risk (OR: 1.11, 95% CI: 0.99–1.24, p=0.08), and very heavy drinking (more than 3 drinks/day) was associated with a significant increased risk (OR: 1.25, 95% CI: 1.11–1.40, p<0.001)... These results provide further evidence that there is a J-shaped association between alcohol consumption and CRC risk.
I guess these sites don't bring up drinking because except for very heavy drinking the data says it's not a factor.
This finding is crazy! I wonder how many modern health issues have to do with healthy blood/nutrient flow to tissues, that are basically solved with either mild/moderately amounts of movement and a balanced diet.
Even in Czechia, where the combination of traditional "heavy" food and, probably, some sort of genetic burden (people with Czech ancestry tend to suffer from colorectal cancers even if they live in regions with very different diets) used to make us the record holders, mortality has gone significantly down.
Humanity seems to be getting this particular snake in its grip.
Fiber is so inconvenient to get in adequate quantity. We cook all our meals using tons of vegetables and none of it has much fiber if I remember. Occasionally I’ll try to start eating oatmeal but get burned out after a week or two.
My breakfast: 80g oats, 2tbsp chia seeds, 1tbsp ground flax, a shitload of frozen berries, 50g of mixed nuts (walnuts, almonds, whatever), raisins or other dried fruit
Delicious and has more than the recommended fiber in one meal. I didn't like oats much until I learnt how to make them taste good
There are apparently cases of psyllium leading to weird allergic reactions. IIRC this is frequently reported in caretakers who prepare psyllium for eldery patients, presumably because they end up inhaling some of the stuff?
It doesn't look like meat consumption was mentioned anywhere.
Frequent consumption of red and processed meat is strongly linked to a higher risk of colorectal cancer, with studies showing a 30% to 40% increased risk for high consumption levels [1]. Processed meat, in particular, raises CRC risk by about 18% for every 50-gram daily portion [2].
Your ultra-endurance athletes might be convinced they need more protein in their diets and are most likely consuming large quantities of meat.
Why would meat cause a decrease in incidence for older folks but a higher incidence for younger folks?
Additionally, the risks you quantify for general cancer incidence are at the bottom odds ratios listed at the end for early-onset. Speculating that ultra-endurance athletes eat tons of meat, without any evidence, seems quite misplaced.
From the discussion section, "It is important to note that inadequate intake in the athletes of the present study may carry significant negative health implications. Insufficient consumption of fruits and wholegrains has been linked to the development of chronic diseases, including CVD, cancer, T2D, and hypertension. Additionally, high intake of sodium, saturated fat and discretionary food items are correlated with higher incidence of obesity, T2D, CVD, dementia, and cancer. Paradoxically, despite exceeding the WHO guidelines for physical activity by a substantial margin, these athletes are not meeting dietary recommendations essential for long-term health, highlighting the potential risks posed by these inadequacies."
Low fiber is quite interesting though, even if it alone doesn't quite explain the massive increase in risk that is observed, at least as I understand it. Correlation between low fiber and high meat consumption would be interesting to investigate as well.
Though ostensibly supportive of your claim, the first article says it best a few pages in (surprisingly honest):
"To date, there are no clearly established biological mechanisms that could explain the role of red and processed meat in the process of CRC carcinogenesis."
In other words, we see some small signal in epidemiological studies, and we want to speculate about mechanistic causes, even though this has been tried before to no success.
I would point to the conclusion of the study: "Red and processed meat consumption and its interaction with the gut microbiota are found to be major associated factors. The CRC-associated gut microbiota is made of pro-inflammatory or pro-carcinogenic bacteria and opportunistic pathogenic bacteria that enrich the tumor microenvironment by promoting disease progression."
I would also add that the World Health Organization after evaluating 800 studies classified processed meat as a Group 1 carcinogen back in 2015, indicating a strong causal link to colorectal cancer, placing it in the same risk category as tobacco. [1]
While I linked to a single study in my original comment, I believe the results are more than a small signal.. enough for the WHO to come out and say processed meat does in fact have a causal link to CRC.
I just hate associative claims that delicately prance around the word “causality”.
I’m sure that we could run a casual analysis on this, though my cursory search yielded nothing, probably because the claim that a certain level of red meat consumption causes certain cancers in humans is not really falsifiable (though we have a plausible biological mechanism to explain it).
I know some biostatisticians but only one or two would have the training to conduct such an analysis, and I wouldn’t trust a statistician in theoretical causality to handle it.
The graph showing risk factors in age groups 18-49 is interesting - obesity, "sugary drinks (>2/day)", and sedentary lifestyle (>2 hr TV/day) are each about 1.5-2x increase in risk factor. Obesity has roughly doubled over this time period, and people are more sedentary. What I could find about "sugary drinks" seems to indicate it hasn't changed much or even dropped slightly over this time. So obesity/sedentary lifestyle probably explains a lot of the increase (maybe not everything, but probably close; a 50% increase in population incidence, where a ~2x risk factor affected ~50% of the population would explain it.)
Obviously this is just anecdotal and you could still be correct, but the two celebrities the article cited (Chadwick Boseman and James Van Der Beek) don’t seem to fit that mold.
Excellent content. The delivery mechanism of the site cited is very polarizing! At the very least it’s generated a lot of opinions. If I think of the target audience used to TikTok engagements it makes a lot of sense. It’s swipey influenced and interactive. It breaks the back button oh well we have browser tabs right?
The web is best for me when experimental UX like this is tried out.
If you screen more people for the disease, and do it better, such that you reduce the incidences and fatalities in the 50+ cohort, that improvement logically implies that you must be catching incidences in the under 50 cohort. So it's going to skew the numbers. Incidences that would have been tallied in the 50+ cohort, are now counted in the under 50.
E.g. a 45-year-old with a latent colorectal cancer who would previously not have been diagnosed early, but only late when they developed symtpoms, by which time they hit 50, would have counted as an incidence or a likely fatality, among the 50+ data. But if that same individual had been caught at 45, they would have counted as an incidence against int he under-50 cohort.
Earlier, better and more available screening alone will shift the data this way.
This mostly can't explain the fact that mortality is also rising in under 50s. It is true mortality is rising less than incident, and that a small proportion instances of mortality could be deaths related to reasonable risks taken on from treatment side effects (to make up numbers, it makes sense to take a 5% chance of dying from treatment this year over a 80% chance of dying from cancer in 5 years), but this is probably not the whole effect. Something is causing more CRC in people under 50.
Go look at the graphs again. The “split by age” graph shows an increase in diagnosis of ~60%, but an increase in mortality of only ~10%. That’s not a small difference, and we aren’t that good at curing colon cancer.
GP’s hypothesis is one of the leading explanations for this trend, but of course gets rejected by advocates for colonoscopy. Taking into account error bars on these numbers (which author doesn’t show, because they are inconvenient to the argument being made), it seems at least somewhat likely that the explanation for the rise in younger cases is due to increased screening, with the “increased” mortality either being statistical noise, or misattribution of deaths that also would have occurred in earlier periods.
Does treatment ever speed up death? Given that chemo is super hard on the body I imagine it could? That might just account for your use of “mostly”, though.
It would depend on the treatment. In my case I had neoadjuvant radiation followed by chemo, then surgery, capped off with more chemo to kill any cancer cells that might have tried to make a dash for it. I would assume that while the radiation treatment elevated my risk for future cancers, the greater risk was my 10 hour surgical procedure.
No, it can't explain that; but the rise is very small. On the per 100,000 mortality graphs divided into the age cohorts, the under fifty mortality is almost a flat line. There is something there, but it doesn't seem like a huge alarm.
Australia has a national screening program, originally for over-50s but now also open to 45-49yo to request a home test kit. You'll get a kit every two years, and should they find blood in the sample they will then refer you to get a colonoscopy exam.
They should probably extend the eligibility to these younger high-risk groups.
Just want to thank the author and poster for sharing this. These are the thoughtful, intellectual, helpful articles that make this site worth continuing to come back to. Ditto on the discussion.
How much of the rise do the listed later on (endurance athletes, obesity, sugary drinks, sedentary lifestyle) explain the relative youth rise? After all, some of this was an issue in 2006 as it is in 2026. Does it explain most of the relative rise, or is there a major missing piece / a mystery still to be explained? I doubt the % of endurance athletes changed meaningfully population-wide, to be a major contributing factor, for example.
I had to have a good read of the article and put the content in ChatGPT for further more detailed analysis. I still can’t infer a single thing about how I should be surprised or how people’s habits changed, so feel free to enlighten me!
Food delivery is now an "essential" for more people than it ever was before. Doordash/Uber Eats is how a weirdly large amount of people eat in general.
The rate of increase in childhood obesity went up during covid.
You realize that is far too recent to show up in cancer death rates for under-40 year olds right? It takes 10-15 years for a change-in-behavior to show up in incidence and even longer for deaths. As a classic example, see the shift (i.e. the delay) in curve of reduced smoking and reduced lung cancer.
Nonsense. There are many ways to get free or reduced price medical care in the US, especially if you are poor. Your doctor will have resources to help you if needed.
You can also rack up huge medical debt and then not pay it. The hospital will sell your debt to bill collectors who will call you for a while, and eventually sue you. At that point you can offer to settle for pennies on the dollar, or you might lose the lawsuit and have to declare bankruptcy which would mean you have negative credit for a few years.
Obviously it will be a difficult time, and hopefully you have something else, but they won't just let you die because you can't afford it.
> There are many ways to get free or reduced price medical care in the US, especially if you are poor.
"In the US" here is a bit misleading because it conflates places where the poor have reliable access to needed healthcare with the places they do not.
> Your doctor will have resources to help you if needed.
This seems presumptuous. More so because we just discussed this and he does not. To be fair, it was expected.
> You can also rack up huge medical debt and then not pay it.
This is a simple declarative statement in the face of a complex issue. It does not (and can not) meaningfully address the required nuances. For example that the medicaid isn't available (red state), that surgery is beyond the scope of the sole social provider (Good Samaritan) or persuading any one of our (rural for-profit) hospitals that non-urgent oncological care should be provided due to EMTALA.
And thru 25yrs of care giving my disabled spouse and 15yrs servicing the medical community, I've learned a bit about what is and isn't available in this place.
Also if you have a low paying job its probably not a big loss to quit it and go on Medicaid if you have a six or seven figure illness. Though it seems like they are trying to change this path for 2027.
If someone is dying of colorectal cancer, trying to get them to worry about their credit score is not only not helpful, it's actively harmful. Messing up your credit for a few years is in the category of "inconvenience" and it's not the kind of thing that you need to worry about when surviving cancer.
You’re right. I am just bitter and angry because I have to get my endoscopy done and I owe my life to my doctoral program that gives me excellent health insurance.
I stopped after the 4th click, I found it irritating to have to click to get 1 or 2 sentences at a time. This would have been just fine as a short article, making it interactive annoyed me more than the revealed content informed.
I think they could do pretty well just not adding bubble gum or whatever nasty flavors the prep has. Sure it'll still be unpleasant and salty, but burping up that nonsense all day really doesn't make it better.
Depending on the doctor some are now recommending getting a tub of miralax, mixing it all into gatorade, and using that for prep instead of the prescription stuff.
Still sucks, but at least it isn't a disgusting flavor, although I haven't had a desire for blue gatorade in the last 3 years
This may be regional but I just had pills. It was fine. My first one had that terrible salty liquid and I cannot stand the salt. I had a very hard time with it, despite adding some flavoring. I just can't drink salt water. So my second one I got pills and it was miles and miles easier. Now the hardest part is fasting for a day.
When I got my second, I had a bidet and it made a huge difference. That and a bit of vaseline to prevent too much irritation. It's an uncomfortable process so taking every win you can saves your sanity
I really didn't mind the prep experience. I can't say it was pleasant, but not a big deal. For me the worst part is the risk of perforation: it's rare but adds risk to the procedure.
My layman's thoughts are it has something to do with young people spending way too much time on the toilet sitting doomscrolling on their phones. (also yes to microplastics and endocrine disruptiors)
Also, hope that bidets may help with it in some way? Bidets supposedly reduce hemorrhoids.
It's rare to see a website that fails to display anything without JS being enabled that also has such nice looking code. I'm both disappointed and impressed! Reading between the script tags was enough to get the idea at least
i disagree. content is great. hitting back button messes stuff up for me. a long form article is preferred for me but maybe this is better for people used to swiping.
> But that progress belongs almost entirely to people 50 and over. For people under 50, both incidence and mortality have been climbing. CRC is now the #1 cancer killer in men under 50.
You need to go to the 2nd screen "Split by age group"
You didn't actually click and read anything. Hank's page is saying exactly what the article you linked is saying. CRC is on the rise in young people. I'm not sure why the moderators changed the title of this post. It should be "Something is Going on with Colorectal Cancer."
Excellent science communication, as would be expected from this author.
A recent finding from last year looked at the mutational signatures in colon cancer in those under 50:
https://www.nature.com/articles/s41586-025-09025-8
The different processes that damage DNA have sequence preferences for the direct change in the DNA (e.g. G-->C versus G-->T), as well as the sequence around the damage. Smoking causes very very different signatures of DNA damage than, say, damage from UV from being in the sun.
So every cell in our body carries with it a (noisy) history of the mutagenic processes it has been exposed to.
This paper found some differences in these mutational signatures of later colon cancers, and attributed them to colibactin, a mutagen produced by bacteria.
It remains to be seen what percentage of the increase in under-50 colon cancers this would explain, but it's an additional risk factor that didn't make it onto the chart, likely because it's not coming from standard epidemiological analysis, and instead from the world of molecular analysis.
Wow, I had no idea there is a 15X increase for endurance athletes. Make me want to dial down the running a bit, which make you wonder where the sweet spot is for distance training.
I wonder if it's due to diet. Endurance athletes love their simple carbs, highly processed gels. I've seen plenty of cyclists taking gummy bears on rides for fuel, or a concoction that is effectively sugar water to drink
The study referenced is really light on details and they don't say if they controlled for that
I was thinking the same thing.
Simple sugars and highly processed foods tends to affect the gut microbiome.
I guess "more ressearch is needed".
It's rare but can happen where long distance running causes ischemic colitis which is where on a long run enough blood is diverted from the large intestine that it damages the intestine long term. It isn't surprising to me that there's higher likelihood of colon cancer given this. It seems like repeated bouts of lower blood for the intestine on long runs has a cumulative impact and damages the colon even if it doesn't cause ischemic colitis.
This theory has been put forward, but it's important to point out that there is no real evidence yet. An alternative theory is diet, which is also the leading theory for increasing incidences in non-athletes. Highly processed, calorie dense foods have been on the watchlist for a while, and ultra endurance athletes have a special need for these to satisfy their caloric requirements. It could also be a combination of these factors or something else that was missed entirely so far.
Interesting, I wasn't aware of that connection either. I was diagnosed with stage IV colon cancer, but was identified as 'genetic' and not caused by diet or lifestyle. I used to be a heavy runner too, done a few marathons, and plenty more 10k, 8ks etc. Wonder if that could be a correlation... Treatments have it contained/in maintenance so at least I have that going for me.
I too was diagnosed with stage 2 rectal cancer, but it was back in 2005. How did they determine your cause was genetic?
Did the genetic genome tests from the biopsy, from a third party company. Helped guide the treatments.
Ah, that definitely wasn't offered to me as an option. Glad to see the progress however. It would be nice if there was an alternative test so that I could tell my kids it's not genetic.
Best of luck with your treatment.
I have an ultra-runner friend who just got diagnosed with stage 4 colon cancer. Absolutely devastating. He had a colonoscopy just a few years ago. His only symptom was not feeling well after a long race.
It may be the damage of repetitive motion, it may be chemicals released into the bloodstream from endurance athletics. It may be something else. Without knowing the root cause, it's impossible to figure out the "sweet spot"
Could be a lot of things. Lots of long distance runners consume a lot of sugary gels to keep going. Not sure what the typical composition is, but likely lots of glucose and no fibre.
The marathon runners I know also seem to eat tons of junk food, they can get away with it from a weight perspective because a long run will burn it off, but it could have other consequences.
Point being: there's a lot about long distance runners that's quite different from other people.
But the rates of obese people who presumably consume a lot of sugars and carbs are 1/10th the rate of ultra marathon runners. It's scary to think that such conditioned athletes could be subject to this horrible disease.
i saw something recently that pointed to the fact that ultra runners end up with less blood in their guts while running for SO long its leading to cancers and such.
This makes the most sense to me. I wonder how long distance cycling compares given that they can go for even longer than runners.
It's not simply endurance athletes though. It was 2x ultra-marathons >26 miles, or at least 5 marathons completed.
>2x ultra-marathons >26 miles, or at least 5 marathons completed
Yes, and it seems like it's really a 7.5x risk increase. Still pretty spectacular, though!
I really wonder what could cause that. Randomly throwing out possible causes: 1) blood redirected away from gut, 2) overuse of NSAIDS, 3) ultraprocessed foods (gels etc), 4) strange microbiome issues (gels + stress in gut from extreme exertion = altered gut flora?)
The study that found the result is DOI: 10.1200/JCO.2025.43.16_suppl.3619
Which is way more than what original hunters and gatherers ever clock. They do move a lot, but not so much, and they alternate their activities a lot too (running, walking, resting, taking entire days off and just guarding their village).
We're not really optimized for this sort of extreme endurance and long-term development of serious pathologies is unsuprising.
You shouldn't so offhandedly assume a hunter-gatherer lifestyle couldn't lead to issues like increased risk of CRC, or that activities which lead to increased risk of CRC couldn't be what hunter-gatherers did. Evolution is neither fast nor perfectly precise. Plenty of animal populations have common health problems that simply weren't harmful enough to reproduction to be selected out, much less something rare and late-onset like CRC.
I don't assume anything. From what we know about health of the last surviving hunter-gatherers, they suffer significantly less from "diseases of civilization" when taken in proportion to their settled neighbours. Some of those diseases (such as high blood pressure or diabetes 2nd type) seem to be totally absent in them. Cancers do happen, but not as often.
This pattern is quite old. Already ancient Egyptians suffered from civilizational diseases much more than hunter-gatherers, especially the richer ones (heart attacks, gout, cancer).
I won't bother checking or disputing the accuracy of your factual claims, because it does not matter.
Colorectal cancer is not the same thing as high blood pressure, or type 2 diabetes, or any other cancer that isn't colorectal cancer. Diseases are not a monolith and you cannot assume low risk of some diseases means low risk of others. That is wild guesswork passed off as logic, like measuring the shadow your testicles cast on the wall and announcing it is 24.1 degrees Celsius. Ultra-marathon runners also have low risk of type 2 diabetes!
Do you have specific evidence that modern hunter-gatherers have low rates of colorectal cancer that cannot be explained by survivorship bias, screening, genetic differences, and all other confounders, and that they are representative of historical hunter-gatherers? No? Then you cannot confidently conclude that hunter-gatherers didn't experience elevated rates of CRC.
Absolutely, we may have a depressed rate of CRC where ultramarathoners just get back up to the historical baseline. Who knows, but we don’t know it isn’t that.
"Diseases are not a monolith and you cannot assume low risk of some diseases means low risk of others. That is wild guesswork passed off as logic..."
Diseases are not a monolith, but they do tend to arise and fall in some specific clusters, and that is not "logic", good or bad (too many computer-minded people drag logic into the chaos that is biology), but rather a long-time empirical observation, albeit with some exceptions.
Your testicles, empirically, shrink when it gets cold. Do you think measuring their shadow is an acceptable substitute for a thermometer?
You are really obsessed with my testicles. That is a weird comparison, but at least you know that you're not a bot. This would be too weird for a LLM to produce.
In general, I don't think your irony is as strong as you think. Shrinkage of various materials in the cold is the original basis for a thermometer.
Of course it is better to use something better-observable like mercury. But in absence of an industrial civilization, you don't have mercury to measure.
Sigh. Sure, if you had a gun to your head and you knew nothing else, it would be better to guess that a given population (hunter-gatherers) with low rates of some illnesses (T2D, HBP) also had low rates of another illness (CRC) than the reverse. Okay. That's a slightly better-than-chance guess, not anywhere near a solid basis for speculation.
"Anyways, it makes sense that marathoners get CRC because hunter-gatherers probably don't run that much" is bongcloud lalaland tier guesswork.
"makes sense that marathoners get CRC because hunter-gatherers probably don't run that much"
That is a misinterpretation of what I wrote. Let me reformulate.
"Marathons are so much more extreme than what we used to do in the Stone Age, that some pathologies resulting from such long-term physical overload are to be expected." I don't see anything lala about that. You do extreme things, you reap some consequences, sooner or later.
I would say that marathons go beyond our design parameters, but my experience in HN is that the "design" metaphor always conjures some people who consider it a dog-whistle for intelligent design (as opposed to evolution), not just an imprecise metaphor, as metaphors usually are. So I avoid it in order not to attract a senseless fight.
I’m in my early 30s and am starting to think about getting a screening. Problem is, it’s not trivial to do. You have to really upsell your doctor to get one so early, even though it’s a relatively benign procedure.
There is a noninvasive testing method called Shield but it is way too flawed to be reliable (with poor positive rates for malignant tumors)
> even though it’s a relatively benign procedure.
Not completely. Every once in a while they accidentally puncture the intestine with the probes and that becomes a significant medial problem. It doesn't happen often, but that is still a risk that doctors need to consider. If you are over 50 getting one every 10 years is a good idea, and there is some consideration if younger might be worth it. However so few people get colon cancer under 40 that it isn't worth the risks for most - but if there are other signs of a problem (either family history or symptoms) that changes things and it may be worth it.
I was diagnosed at 35 seven years ago with no history. Getting a colonoscopy never crossed my mind, much less being suggested by my general practitioner.
The trigger for me was blood in my stool. It was the slightest amount but I pursued it because that didn’t seem right. Turns out I had hemorrhoids which brought up something I feel hits others - I was embarrassed.
Fortunately the doctor that performed a banding procedure pushed me to get a colonoscopy purely out of being through and seeing the number of incidences increase at my age range.
I often wonder how much the embarrassment factor comes into play here.
Blood in the stool, at age 41. Benign but a VERY large polyp so I have a followup soon. If you have an instinct to get tested, especially if you have any evidence, do it. My doc fought me to NOT get tested but I persisted. The embarrassment factor is a thing, but we have to get over it!
Was it a consistent blood in stools or just a one time thing? I've had what I think that is once or twice and then take the approach to just see if it recoccurs a second time before going to a doctor, not sure if that's the correct approach or if a single instance should be alarming enough.
For me it was small amount consistently. But I cannot stress enough that it was the diagnosis of hemorrhoids coupled with a very proactive doctor that led to me being diagnosed with cancer. It was a lucky circumstance that it was staged early because the additionally suggested screening was not standard protocol for my age.
If you have any abnormalities in your bowel movements (blood, ribboning, etc.) and you have the ability to get it checked then it could offer peace of mind. And yes, there are small chances of intestinal perforations with a colonoscopy.
My bloody stool started slow and took some time off but came back and I had a large polyp. Watch this very closely, but don't panic.
For a screening procedure recommended as a mass conducted preventative measure in otherwise healthy people, harms must be regulated to a better standard than "doesn't happen often". The study that I read of was about serious issue occuring something like one in 120 procedures. It was done at Kaiser. Next time you're enjoying a sausage, take a moment to look at the sausage skins. If I understand correctly, our intestinal walls are quite thin, and even the colon vulnerable.
If you tell your doctor that a parent had polyps removed (say, recently), that will give you your best chance of getting one. Most likely, if you're in an even remotely progressive area, your doc wants you to have one, but their hands are tied by the insurance company. Afaik you dont have to provide any proof of your claim re parental polyps.
> but their hands are tied by the insurance company.
Doctors' ability to prescribe or refer is never restricted by an insurance company. If they think a patient should get whatever healthcare, they are free to say it.
The average American says US healthcare spending, which is 3x to 20x that of other OECD countries on a per capita basis, is way too high.
The average American also thinks they should be provided testing and procedures that their insurance deems medically unnecessary.
Try to reconcile these two beliefs. (Hint: It's impossible)
Maybe there's a bunch of inflated profit margins and people getting filthy rich off a poorly regulated market.
You are just ignoring their intended meaning. Boring.
Is the intended meaning that health insurance should pay for anything and everything? Even systems where the government pays directly like the UK have parameters under which the government will pay for a procedure or medicine.
Not at all. Patients are free to pay out of pocket for procedures not covered by insurance. An extra colonoscopy (one not classified as medically necessary), while expensive, is within the financial means of most middle-class adults.
In CA, my doctor can refer me to get a Cologuard. But it's private pay, and they want payment up front since isurance companies don't restrict doctor's ability, only reimbursement.
So they may not be willing (even though they are able) perform procedure/test if they aren't confident they'll get paid.
> I’m in my early 30s and am starting to think about getting a screening.
This is a pretty stupid thing to do unless you've had some sort of symptom or family history. Your protection from illness due to screening is statistical, and jumping out of the calculated recommendation just makes it more likely to hurt you (false positives, false negatives, injuries from the procedure) than to benefit you.
Desperately trying to fabricate a reason is just intentionally trying to hurt yourself.
I'm not against colonoscopies (is anyone?) and I personally had my first one early because of an odd pain. Turned out to be unrelated.
edit: the neurotic desperation for disease screening that I see in a lot of people bothers me a lot because it's this odd fetishization of medical science combined with the active subversion of it. For me it's a weird insistence that all tests are good but that the math behind them is not.
From a 'public health' perspective, it makes perfect sense to limit the frequency of screening procedures by age and other broad risk-factors, but that doesn't help at the individual level if you fall on the unlucky side of those statistics.
Most cancers are still very much lethal once they progress to a certain point, and the best treatment we know of is early detection. Many of the cancer screens are harmless or don't add significant risk of death, so it really comes down to money and medical resource availability (also solved with money.)
I don't see much difference in someone paying out-of-pocket for a full-body MRI/colonoscopy vs. them spending way above average on any other item that slightly reduces the risk of dying (how many smoke alarms and fire extinguishers does your home have?)
> that doesn't help at the individual level if you fall on the unlucky side of those statistics
As GP stated, there's the other unlucky side of the statistics with false positives.
Lie about family history, but even colonoscopies are not perfect; I just had somebody in my family die of CRC because...
- They had symptoms and wanted a screening, but their PCP repeatedly denied them a referral for like a year because they were "too young".
- They lied about family history after symptoms got worse and got their referral.
- They got the colonoscopy which came back clean, and then symptoms continued to get worse.
- Finally their doctor gave them a referral for an MRI.
Results were stage 4 CRC. The doctor performing the colonoscopy missed the tumor, which was tucked into the sigmoid (the bend in your colon), where he didn't properly inflate because he wasn't taking it very seriously. It had a thumb-tip sized protrusion inside the colon but had gotten huge on the opposite side of the colon wall. They fought it for 8 years after the diagnosis and over 100 rounds of chemo (!!!), were about to get a new procedure at Yale, in which the doctor told them to think of it in terms of "this really may be a complete cure", but it was canceled because of the Big Beautiful Bill.
If you have symptoms (even if you don't), don't let some fuckass Nurse Practitioner tell you no. They don't know shit and they let their egos get in the way when they have to deal with moderately informed patients advocating for themselves. This was preventable and tge medicap system failed them because both the PCP and the doctor performing the colonoscopy were not paying attention to what they were being presented with and saw only their own expectations.
Also...apparently doctors wanted to lower the screening age to like 35, but insurance companies fought it, so it's at 45.
>Also...apparently doctors wanted to lower the screening age to like 35, but insurance companies fought it, so it's at 45.
On this website, it is frequently opined that because health insurers have a legal minimum medical loss ratio, that health insurers prefer inflated costs so that their medical losses are higher, which means their premiums can be higher, which means their revenue is higher, which means their profit is higher.
I would have thought health insurers would support a lower screening age, especially since it would inflate costs for all insurers so everyone's cut of the now bigger pie gets bigger.
IANAL, just a CRC survivor and one who had my PCP miss my diagnosis a year before I started treatment. You may have a pretty good malpractice claim.
I'm a little removed from the situation, (not my nuclear family) but I believe the statute is up. It's too difficult to litigate in, say, the first two years of your stage 4 diagnosis before the law won't allow a suit.
I've decided to invest $2000/year and get an MRI scan every year. My first one, the baseline, showed nothing remarkable, thank God. I'm scheduled for my second one in a few weeks, I want to be able to catch anything weird very early on. I think it's worth it despite what all the know-it-alls say.
Can an MRI catch it? It would be ideal if the cost of MRIs came down so everyone could access it. Where's Moore's law for ~tricoders~ MRIs?
Would an MRI detect polyps?
while it sucks, paying for it out of pocket is probably cheaper if you can't get it covered. In the long run, $1500 as a bridge until your 40s feels cheaper than stage 4 cancer.
$1500? That sounds optimistic. I'm getting an upper endoscopy tomorrow and they've already told me it will be $4K. The equipment is similar, I expect colonoscopy is not cheaper.
The encouragement is that the rate of "death from colorectal carcinoma" seems to be reduced in studies of screening. This is a 'disease specific' mortality statistic. Most of us don't care why we die, or what is ultimately written upon our death certificates, we would simply rather still be alive! So reduction in "total mortality" would be a more convincing endpoint. If a study of some screening test for a dread disease does NOT show a reduction in the 'total mortality' of the group screened at some clinically reasonable point of time in the future, one could argue that the screening was pointless. Yes, perhaps less people died from the condition being screened for, but if the same number of persons died in the screened -vs- unscreened group, what has been accomplished?
It has been hard, well impossible, to show that screening for colorectal cancer reduces the total or overall death rate. For example, a recent study published in the NEJM in 2022 did find a reduction in persons who died from colorectal carcinoma after screening with colonoscopy. But they did NOT find that the total or overall death rate had decreased!
"The risk of death from any cause was 11.03% in the invited group and 11.04% in the usual-care group (risk ratio, 0.99; 95% CI, 0.96 to 1.04)." N Engl J Med 2022;387:1547-1556 DOI: 10.1056/NEJMoa2208375V
When reading 'screening' studies, one usually needs to look very carefully at the article and published data to find this statistic. Sometimes it is not even reported at all, it is simply ignored. It's almost like the authors don't want the fact that the screening program does not reduce one's risk of dying to any measurable degree is ... embarrassing?
This problem is not unique to colorectal cancer screening.
When studies are designed a key parameter is the statistical power that the size of the stud provides: how big of a difference in the key stat can it find?
I would expect that the design of a study will be able to find differences in the key readout: did screening reduce death in the types of cancer it could find.
Colon cancer deaths are only a small fraction of total mortality, and statistically, finding a small change in a ratio close to zero is far easier to see than a that same change in a ratio that's further away from zero.
So I would not expect a study to be powered to be able to find changes in total mortality from all causes. That would take a far larger number of people and generally be considered a waste of resources that would be better spent investigating other things.
So I wouldn't take the lack of statistical significance in total mortality as evidence of anything, unless total mortality was a primary outcome that was being tested.
Pretty much all the good interventions for reducing mortality will not have much impact on total mortality because there are so many things causing total mortality. But add up all the small ones and it starts to make differences in total mortality.
Something I've never seen in these analyses is drinking. Millennials are heavy drinkers. Both craft brews and cocktails were defining generational traits. Not everyone is a drinker but it appears they are heavy drinkers compared to other generations.
The theory behind the ultra marathoners is that extreme distance running disrupts the epithelial layer and microbiome in the gut. Wouldn't drinking have similar effects?
> Millennials are heavy drinkers.
That's news to millenials and the graveyard of craft breweries. I thought alcohol consumption is trending off for younger generations.
Millennials are not the younger generation anymore. That refers to Gen Z and alpha.
It’s more like, millennials got older and started drinking less (as happens), and Gen Z drinks different things like hard seltzer, and also drinks a bit less overall. Plus there were just way too many craft brewers making hoppy ipa to begin with.
Unfortunately, hoppy IPA seems to constitute the majority of the survivors. I have no interest personally in suffering through another hazy sour grapefruit triple ipa, but that seems to be about 90% of craft brewery output these days.
Interesting, where I live in Brooklyn it seems this is no longer an issue. Tons of non-hoppy craft options like pilsners, stouts, lagers, etc at ~every craft brewery or gastropub.
40% of the US population is older than 45, and millenial includes < 50th percentile.
We're also talking about alcohol consumption. Only half of Gen Z can drink and none of Alpha.
Alcohol has adverse interactions with psych meds, and THC is becoming the recreational drug of choice.
Not yet.
I see one poll by a cannabis outlet claiming 46% of marijuana users are millenials (read: high proportion of user base). However, <20% of millennials smoke marijuana. [0] And another claims <40% use cannabis.
That's still below the ~50% of millennials who consume alcohol.
[0]https://news.gallup.com/poll/284135/percentage-americans-smo...
I hate to break it to you, but Millennials aren't a younger generation anymore...
though I'm not sure they drank any more than the 2-3 generations that proceeded them.
> but Millennials aren't a younger generation anymore...
Not younger than GenX/Baby Boomer? How?
We millennials are all middle age.
There's roughly 4 to 5 generations alive at any point and the middle generation is going to be considered both old and young by the generations surrounding it.
Once Gen beta starts we'll be officially old.
Middle age != Middle generation.
I understand your point. But you're redefining widely accepted usage of these terms. Nobody would call a 30 year old "middle age."
You're right. 8 year olds would call you ancient and 80 year olds would call you a baby. Middle age is relative and unless you're over 45 you don't admit to it, and then hold on to it for too long.
Not to be rude but, google is free:
https://www.google.com/search?q=are+millenials+heavy+drinker...
Well, your first Google result is a blog post that makes my point.
> For example, baby boomers are the generation with the most dramatic increase in harmful alcohol abuse. In contrast, Gen Z prefers the sober lifestyle as they are known to consume alcohol much less than any of their older counterparts, including millennials.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6819207/
> Compared to non-/occasional drinking (≤1 g/day), light/moderate drinking (up to 2 drinks/day) was associated with a decreased risk of CRC (OR: 0.92, 95% CI: 0.88–0.98, p=0.005), heavy drinking (2–3 drinks/day) was not significantly associated with CRC risk (OR: 1.11, 95% CI: 0.99–1.24, p=0.08), and very heavy drinking (more than 3 drinks/day) was associated with a significant increased risk (OR: 1.25, 95% CI: 1.11–1.40, p<0.001)... These results provide further evidence that there is a J-shaped association between alcohol consumption and CRC risk.
I guess these sites don't bring up drinking because except for very heavy drinking the data says it's not a factor.
This finding is crazy! I wonder how many modern health issues have to do with healthy blood/nutrient flow to tissues, that are basically solved with either mild/moderately amounts of movement and a balanced diet.
I thought lots of data indicated that millennials were drinking less than previous generations?
Even in Czechia, where the combination of traditional "heavy" food and, probably, some sort of genetic burden (people with Czech ancestry tend to suffer from colorectal cancers even if they live in regions with very different diets) used to make us the record holders, mortality has gone significantly down.
Humanity seems to be getting this particular snake in its grip.
I wonder why fiber is never brough up with this. Only ~5% of people get enough fiber and it lowers your risk a lot
Fiber is so inconvenient to get in adequate quantity. We cook all our meals using tons of vegetables and none of it has much fiber if I remember. Occasionally I’ll try to start eating oatmeal but get burned out after a week or two.
My breakfast: 80g oats, 2tbsp chia seeds, 1tbsp ground flax, a shitload of frozen berries, 50g of mixed nuts (walnuts, almonds, whatever), raisins or other dried fruit
Delicious and has more than the recommended fiber in one meal. I didn't like oats much until I learnt how to make them taste good
This is close to a recipe suggestion on Bob’s Red Mill Muesli.
I would assemble it the night before, so that the berry juice moistened the oats.
Cardamom or cinnamon, honey, or plain yogurt can be added.
Sounds good how is this prepared?
How do you make them taste good? I need to put sugar on oatmeal... Lol
So put sugar.
I eat a lot of fibrous frankenfoods and I’m not sure if the net effect is positive, but I think it helps my bowel movements…
It’s covered in the risk factors section at the end.
Ah, you're right.
I actually looked it up after I made that comment and it looks to be a 10% reduction in relative risk per 10g extra fiber consumed
Considering Americans as an example only get 10-15g per day, and it's perfectly possible to get 60g.. that could have a huge impact
You can buy Psyllium husks by the pound as well.
There are apparently cases of psyllium leading to weird allergic reactions. IIRC this is frequently reported in caretakers who prepare psyllium for eldery patients, presumably because they end up inhaling some of the stuff?
It doesn't look like meat consumption was mentioned anywhere.
Frequent consumption of red and processed meat is strongly linked to a higher risk of colorectal cancer, with studies showing a 30% to 40% increased risk for high consumption levels [1]. Processed meat, in particular, raises CRC risk by about 18% for every 50-gram daily portion [2].
Your ultra-endurance athletes might be convinced they need more protein in their diets and are most likely consuming large quantities of meat.
1: https://pmc.ncbi.nlm.nih.gov/articles/PMC10194058/
2: https://www.umassmed.edu/news/news-archives/2015/10/umms-col...
Why would meat cause a decrease in incidence for older folks but a higher incidence for younger folks?
Additionally, the risks you quantify for general cancer incidence are at the bottom odds ratios listed at the end for early-onset. Speculating that ultra-endurance athletes eat tons of meat, without any evidence, seems quite misplaced.
2025 study on the diet quality of ultra-marathon runners: https://pmc.ncbi.nlm.nih.gov/articles/PMC11820624/
From the discussion section, "It is important to note that inadequate intake in the athletes of the present study may carry significant negative health implications. Insufficient consumption of fruits and wholegrains has been linked to the development of chronic diseases, including CVD, cancer, T2D, and hypertension. Additionally, high intake of sodium, saturated fat and discretionary food items are correlated with higher incidence of obesity, T2D, CVD, dementia, and cancer. Paradoxically, despite exceeding the WHO guidelines for physical activity by a substantial margin, these athletes are not meeting dietary recommendations essential for long-term health, highlighting the potential risks posed by these inadequacies."
Interestingly no mention of meat there.
Low fiber is quite interesting though, even if it alone doesn't quite explain the massive increase in risk that is observed, at least as I understand it. Correlation between low fiber and high meat consumption would be interesting to investigate as well.
Though ostensibly supportive of your claim, the first article says it best a few pages in (surprisingly honest):
"To date, there are no clearly established biological mechanisms that could explain the role of red and processed meat in the process of CRC carcinogenesis."
In other words, we see some small signal in epidemiological studies, and we want to speculate about mechanistic causes, even though this has been tried before to no success.
I would point to the conclusion of the study: "Red and processed meat consumption and its interaction with the gut microbiota are found to be major associated factors. The CRC-associated gut microbiota is made of pro-inflammatory or pro-carcinogenic bacteria and opportunistic pathogenic bacteria that enrich the tumor microenvironment by promoting disease progression."
I would also add that the World Health Organization after evaluating 800 studies classified processed meat as a Group 1 carcinogen back in 2015, indicating a strong causal link to colorectal cancer, placing it in the same risk category as tobacco. [1]
While I linked to a single study in my original comment, I believe the results are more than a small signal.. enough for the WHO to come out and say processed meat does in fact have a causal link to CRC.
1: https://nutritionsource.hsph.harvard.edu/2015/11/03/report-s...
I just hate associative claims that delicately prance around the word “causality”.
I’m sure that we could run a casual analysis on this, though my cursory search yielded nothing, probably because the claim that a certain level of red meat consumption causes certain cancers in humans is not really falsifiable (though we have a plausible biological mechanism to explain it).
I know some biostatisticians but only one or two would have the training to conduct such an analysis, and I wouldn’t trust a statistician in theoretical causality to handle it.
The graph showing risk factors in age groups 18-49 is interesting - obesity, "sugary drinks (>2/day)", and sedentary lifestyle (>2 hr TV/day) are each about 1.5-2x increase in risk factor. Obesity has roughly doubled over this time period, and people are more sedentary. What I could find about "sugary drinks" seems to indicate it hasn't changed much or even dropped slightly over this time. So obesity/sedentary lifestyle probably explains a lot of the increase (maybe not everything, but probably close; a 50% increase in population incidence, where a ~2x risk factor affected ~50% of the population would explain it.)
Obviously this is just anecdotal and you could still be correct, but the two celebrities the article cited (Chadwick Boseman and James Van Der Beek) don’t seem to fit that mold.
True, although how many celebrities do?
Excellent content. The delivery mechanism of the site cited is very polarizing! At the very least it’s generated a lot of opinions. If I think of the target audience used to TikTok engagements it makes a lot of sense. It’s swipey influenced and interactive. It breaks the back button oh well we have browser tabs right?
The web is best for me when experimental UX like this is tried out.
If you screen more people for the disease, and do it better, such that you reduce the incidences and fatalities in the 50+ cohort, that improvement logically implies that you must be catching incidences in the under 50 cohort. So it's going to skew the numbers. Incidences that would have been tallied in the 50+ cohort, are now counted in the under 50.
E.g. a 45-year-old with a latent colorectal cancer who would previously not have been diagnosed early, but only late when they developed symtpoms, by which time they hit 50, would have counted as an incidence or a likely fatality, among the 50+ data. But if that same individual had been caught at 45, they would have counted as an incidence against int he under-50 cohort.
Earlier, better and more available screening alone will shift the data this way.
This mostly can't explain the fact that mortality is also rising in under 50s. It is true mortality is rising less than incident, and that a small proportion instances of mortality could be deaths related to reasonable risks taken on from treatment side effects (to make up numbers, it makes sense to take a 5% chance of dying from treatment this year over a 80% chance of dying from cancer in 5 years), but this is probably not the whole effect. Something is causing more CRC in people under 50.
Go look at the graphs again. The “split by age” graph shows an increase in diagnosis of ~60%, but an increase in mortality of only ~10%. That’s not a small difference, and we aren’t that good at curing colon cancer.
GP’s hypothesis is one of the leading explanations for this trend, but of course gets rejected by advocates for colonoscopy. Taking into account error bars on these numbers (which author doesn’t show, because they are inconvenient to the argument being made), it seems at least somewhat likely that the explanation for the rise in younger cases is due to increased screening, with the “increased” mortality either being statistical noise, or misattribution of deaths that also would have occurred in earlier periods.
Does treatment ever speed up death? Given that chemo is super hard on the body I imagine it could? That might just account for your use of “mostly”, though.
It would depend on the treatment. In my case I had neoadjuvant radiation followed by chemo, then surgery, capped off with more chemo to kill any cancer cells that might have tried to make a dash for it. I would assume that while the radiation treatment elevated my risk for future cancers, the greater risk was my 10 hour surgical procedure.
C'mon, I already said that, that was half of my comment!
No, it can't explain that; but the rise is very small. On the per 100,000 mortality graphs divided into the age cohorts, the under fifty mortality is almost a flat line. There is something there, but it doesn't seem like a huge alarm.
[dead]
Hey Hank, if youre on HN, you're one of my favorite humans that I don't personally know.
If Hank Green even knew what Hacker News was, I think my respect for him would diminish considerably.
Australia has a national screening program, originally for over-50s but now also open to 45-49yo to request a home test kit. You'll get a kit every two years, and should they find blood in the sample they will then refer you to get a colonoscopy exam.
They should probably extend the eligibility to these younger high-risk groups.
https://www.health.gov.au/our-work/national-bowel-cancer-scr...
Just want to thank the author and poster for sharing this. These are the thoughtful, intellectual, helpful articles that make this site worth continuing to come back to. Ditto on the discussion.
How much of the rise do the listed later on (endurance athletes, obesity, sugary drinks, sedentary lifestyle) explain the relative youth rise? After all, some of this was an issue in 2006 as it is in 2026. Does it explain most of the relative rise, or is there a major missing piece / a mystery still to be explained? I doubt the % of endurance athletes changed meaningfully population-wide, to be a major contributing factor, for example.
You'd be surprised. COVID-19 fundamentally altered a lot of people's habits.
https://www.businessofapps.com/data/strava-statistics/
I had to have a good read of the article and put the content in ChatGPT for further more detailed analysis. I still can’t infer a single thing about how I should be surprised or how people’s habits changed, so feel free to enlighten me!
Food delivery is now an "essential" for more people than it ever was before. Doordash/Uber Eats is how a weirdly large amount of people eat in general.
The rate of increase in childhood obesity went up during covid.
You realize that is far too recent to show up in cancer death rates for under-40 year olds right? It takes 10-15 years for a change-in-behavior to show up in incidence and even longer for deaths. As a classic example, see the shift (i.e. the delay) in curve of reduced smoking and reduced lung cancer.
your reply is better two layers up
One of Europe's leading nutrition experts also highlighted energy drinks in connection with the growing incidence of colon cancer among young people.
What evidence is there of that?
Sugary drinks is one of the cited contributers in this piece.
My Dr just ordered a test for colon cancer. If it's positive, I'm dead. I don't have enough savings to score a hospital bed, nevertheless surgery.
In this, I'm in the same boat as millions of other Americans. Positive medical news rarely applies to us.
Nonsense. There are many ways to get free or reduced price medical care in the US, especially if you are poor. Your doctor will have resources to help you if needed.
You can also rack up huge medical debt and then not pay it. The hospital will sell your debt to bill collectors who will call you for a while, and eventually sue you. At that point you can offer to settle for pennies on the dollar, or you might lose the lawsuit and have to declare bankruptcy which would mean you have negative credit for a few years.
Obviously it will be a difficult time, and hopefully you have something else, but they won't just let you die because you can't afford it.
> There are many ways to get free or reduced price medical care in the US, especially if you are poor.
"In the US" here is a bit misleading because it conflates places where the poor have reliable access to needed healthcare with the places they do not.
> Your doctor will have resources to help you if needed.
This seems presumptuous. More so because we just discussed this and he does not. To be fair, it was expected.
> You can also rack up huge medical debt and then not pay it.
This is a simple declarative statement in the face of a complex issue. It does not (and can not) meaningfully address the required nuances. For example that the medicaid isn't available (red state), that surgery is beyond the scope of the sole social provider (Good Samaritan) or persuading any one of our (rural for-profit) hospitals that non-urgent oncological care should be provided due to EMTALA.
And thru 25yrs of care giving my disabled spouse and 15yrs servicing the medical community, I've learned a bit about what is and isn't available in this place.
Also if you have a low paying job its probably not a big loss to quit it and go on Medicaid if you have a six or seven figure illness. Though it seems like they are trying to change this path for 2027.
Well, unfortunately the current administration has blocked a bill that would have prohibited medical debt from reflecting on your credit score.
If someone is dying of colorectal cancer, trying to get them to worry about their credit score is not only not helpful, it's actively harmful. Messing up your credit for a few years is in the category of "inconvenience" and it's not the kind of thing that you need to worry about when surviving cancer.
You’re right. I am just bitter and angry because I have to get my endoscopy done and I owe my life to my doctoral program that gives me excellent health insurance.
I stopped after the 4th click, I found it irritating to have to click to get 1 or 2 sentences at a time. This would have been just fine as a short article, making it interactive annoyed me more than the revealed content informed.
Made even more annoying by the "next page" button constantly moving with the page height.
Very annoying UX, I found it felt like it was breaking continuity and making the ideas on each page disjointed.
Years ago, I went to a show where Hank Green sang a song about his IBS. I still chuckle at the lyric about rerouting his bowel to a spigot.
That being said, I wish this was a normal page that scrolled. The click click click just breaks the web.
If anyone here is up for disrupting the medical field: please come up with a colonoscopy-equivalent with a less awful prep experience.
I think they could do pretty well just not adding bubble gum or whatever nasty flavors the prep has. Sure it'll still be unpleasant and salty, but burping up that nonsense all day really doesn't make it better.
Depending on the doctor some are now recommending getting a tub of miralax, mixing it all into gatorade, and using that for prep instead of the prescription stuff.
Still sucks, but at least it isn't a disgusting flavor, although I haven't had a desire for blue gatorade in the last 3 years
I do this, I have gone through 10 Costco tubs so far in my 1+ year of suffering from chronic constipation
By far the worst part. By far.
Though having to push out a huge fart at the request of the nurse while they stare at you when you wake up is a close 2nd.
I've never heard of that. Is it standard?
This may be regional but I just had pills. It was fine. My first one had that terrible salty liquid and I cannot stand the salt. I had a very hard time with it, despite adding some flavoring. I just can't drink salt water. So my second one I got pills and it was miles and miles easier. Now the hardest part is fasting for a day.
When I got my second, I had a bidet and it made a huge difference. That and a bit of vaseline to prevent too much irritation. It's an uncomfortable process so taking every win you can saves your sanity
I really didn't mind the prep experience. I can't say it was pleasant, but not a big deal. For me the worst part is the risk of perforation: it's rare but adds risk to the procedure.
My layman's thoughts are it has something to do with young people spending way too much time on the toilet sitting doomscrolling on their phones. (also yes to microplastics and endocrine disruptiors)
Also, hope that bidets may help with it in some way? Bidets supposedly reduce hemorrhoids.
I love the way the information is displayed!
[dead]
It's rare to see a website that fails to display anything without JS being enabled that also has such nice looking code. I'm both disappointed and impressed! Reading between the script tags was enough to get the idea at least
Very effective way of conveying information.
I think a major factor is the increase in microplastics in our diets.
https://www.sciencedirect.com/science/article/abs/pii/S18777...
i disagree. content is great. hitting back button messes stuff up for me. a long form article is preferred for me but maybe this is better for people used to swiping.
Strange, because I've heard the exact opposite...
https://www.cbc.ca/news/health/colorectal-cancer-keeps-risin...
That is EXACTLY what the post is saying:
> But that progress belongs almost entirely to people 50 and over. For people under 50, both incidence and mortality have been climbing. CRC is now the #1 cancer killer in men under 50.
You need to go to the 2nd screen "Split by age group"
Maybe their website sucks and all I saw was 2 graphs
You didn't actually click and read anything. Hank's page is saying exactly what the article you linked is saying. CRC is on the rise in young people. I'm not sure why the moderators changed the title of this post. It should be "Something is Going on with Colorectal Cancer."