Overall, the colorectal cancer story is encouraging
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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.
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.
We're not really optimized for this sort of extreme endurance and long-term development of serious pathologies is unsuprising.
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).
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.
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.
"Anyways, it makes sense that marathoners get CRC because hunter-gatherers probably don't run that much" is bongcloud lalaland tier guesswork.
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.
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.
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
The study referenced is really light on details and they don't say if they controlled for that
Simple sugars and highly processed foods tends to affect the gut microbiome.
I guess "more ressearch is needed".
There is a noninvasive testing method called Shield but it is way too flawed to be reliable (with poor positive rates for malignant tumors)
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.
So they may not be willing (even though they are able) perform procedure/test if they aren't confident they'll get paid.
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)
- 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.
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.
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.
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.
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.
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.
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?)
As GP stated, there's the other unlucky side of the statistics with false positives.
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?
That's news to millenials and the graveyard of craft breweries. I thought alcohol consumption is trending off for younger generations.
We're also talking about alcohol consumption. Only half of Gen Z can drink and none of Alpha.
https://www.google.com/search?q=are+millenials+heavy+drinker...
> 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.
though I'm not sure they drank any more than the 2-3 generations that proceeded them.
Not younger than GenX/Baby Boomer? How?
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.
I understand your point. But you're redefining widely accepted usage of these terms. Nobody would call a 30 year old "middle age."
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...
> 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.
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.
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.
Humanity seems to be getting this particular snake in its grip.
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
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
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.
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...
"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 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...
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.
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 web is best for me when experimental UX like this is tried out.
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.
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.
They should probably extend the eligibility to these younger high-risk groups.
https://www.health.gov.au/our-work/national-bowel-cancer-scr...
The rate of increase in childhood obesity went up during covid.
In this, I'm in the same boat as millions of other Americans. Positive medical news rarely applies to us.
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.
"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.
That being said, I wish this was a normal page that scrolled. The click click click just breaks the web.
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
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.
Also, hope that bidets may help with it in some way? Bidets supposedly reduce hemorrhoids.
I think a major factor is the increase in microplastics in our diets.
https://www.sciencedirect.com/science/article/abs/pii/S18777...
https://www.cbc.ca/news/health/colorectal-cancer-keeps-risin...
> 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"