Colon Cancer Is Falling in People My Age and Rising in Yours. Here's Why.

Last week I had a colonoscopy.

I know — not exactly the opener you expected. But stick with me, because what my doctor told me afterward is directly relevant to something that should concern every parent, every young adult, and frankly anyone who eats food in America today.

I'm 65. Several years ago I was told I should be getting annual colonoscopies because of a polyp problem. I'll be honest — I didn't always follow through the way I should have. Last week my doctor told me the polyps are gone and I don't need to come back for five years.

I'm not telling you this to brag. I'm telling you because I think there's a real lesson in why colorectal cancer is declining in people my age while quietly becoming a crisis for younger Americans.

Two Trends Moving in Opposite Directions — and Why

The American Cancer Society's 2026 colorectal cancer statistics show something striking: colorectal cancer is falling by 2.5% per year in adults over 65. In adults ages 20 to 49, it's rising by 3% per year.

Part of the explanation for that gap is actually straightforward: screening. Older Americans are getting colonoscopies. Polyps are found and removed before they turn into cancer. That's exactly how the system is supposed to work, and in people my age, it's working.

Younger Americans historically weren't recommended to screen at all — the guidelines said to start at 50. So cancers that could have been caught early weren't. By the time symptoms appeared, the disease had often already progressed.

That reality forced a change. Medical organizations lowered the recommended screening age from 50 to 45 in 2021. Researchers are now publishing data suggesting it should drop to 40 — a study in JAMA Oncology found that starting screening a decade earlier cut colorectal cancer mortality by 39%.

But screening doesn't explain everything. It explains why we're catching fewer cancers in older adults. It doesn't explain why younger people are developing polyps and tumors at higher rates in the first place. For that answer, researchers have been looking hard at what this generation is eating.

It's Not Just Colorectal Cancer

Before we get to the food connection, it's worth understanding how broad this problem actually is.

A Dana-Farber Cancer Institute literature review found that early-onset gastrointestinal cancers rose by 14.8% between 2010 and 2019 — and it's not limited to the colon. Pancreatic cancer. Esophageal cancer. Stomach cancer. Cancers of the appendix and bile ducts. All rising in younger adults, with the youngest groups experiencing the steepest increases.

Pancreatic cancer deserves particular mention because it is among the most feared diagnoses in medicine. It is notoriously difficult to detect early and carries a five-year survival rate that remains stubbornly low. When researchers start finding it in people in their 30s and 40s, that is not a trend you can afford to ignore.

The Uncomfortable Overlap

Here's what else changed over the past 30 to 40 years, right alongside the rise in early-onset GI cancers: ultra-processed food became the foundation of the American diet.

A Harvard and Mass General Brigham research team spent 24 years tracking nearly 30,000 women in the Nurses Health Study II. They found that women who ate the highest levels of ultra-processed food had a 45% higher risk of developing precancerous colorectal polyps compared to women who ate the least.

Forty-five percent.

This was published in JAMA Oncology. The lead researcher, Dr. Andrew Chan at Mass General, put it plainly: his team was asking what has changed in our environment that mirrors the acceleration in cancer rates. Ultra-processed food is a compelling answer.

The rise in early-onset GI cancers is happening across multiple countries, faster than genetics alone can explain. Researchers are pointing at diet, gut microbiome disruption, obesity, and chronic inflammation — all of which trace back, in significant part, to what people are eating every day.

Why Would You Wait?

If you knew that eating ultra-processed food was strongly correlated with precancerous polyps — the exact thing that precedes colorectal cancer — why would you keep eating it?

I understand the standard response: correlation isn't causation. We need double-blind randomized trials. The science isn't settled.

Here's my answer to that: you will never get a double-blind randomized trial on this question. No ethics board will approve a study that intentionally feeds people food suspected of causing cancer for 20 years to see what happens. The best evidence we are ever going to have is the correlational evidence we already have — and that evidence is consistent, large-scale, and points in one direction.

The asymmetry here matters. The downside of eating ultra-processed food, given what we know, is serious and potentially irreversible. The downside of not eating it is that you eat real food instead.

That is not a difficult trade.

What Changed For Me

I can't prove my diet is why my polyps resolved. My doctor didn't say that. I'm not saying it either.

What I can tell you is that over the past several years, I stopped eating ultra-processed food. I eat grass-fed beef, pasture-raised eggs, raw dairy, and vegetables. I run six miles a day. My metabolic markers have improved consistently. And last week, a gastroenterologist told me my colon looks clean enough that I don't need to come back for five years.

I'm 65. Colorectal cancer is declining in people my age.

The generation that grew up eating Doritos for lunch and fast food for dinner is now in their 20s and 30s. And colorectal cancer is rising in people their age at 3% per year.

I'm not saying I have all the answers. I'm saying the correlation is strong enough that I wouldn't wait for more proof to change what I eat.

Something to think about.

— Chris, Tyner Pond Farm

Frequently Asked Questions

Why is colorectal cancer increasing in young people? Researchers believe multiple factors are at work, including the rise of ultra-processed food as a dietary staple, disruption of the gut microbiome, increasing rates of obesity, and chronic low-grade inflammation. The trend is happening across multiple high-income countries, faster than genetics alone can explain. Younger generations also went decades without any screening recommendation, so cancers that could have been caught early weren't.

Why is colorectal cancer decreasing in older adults? Largely because of screening. When colonoscopies find and remove precancerous polyps before they develop into cancer, the disease never gets a chance to progress. Older Americans have been under screening guidelines for decades. That intervention works — and the falling rates in people over 65 are evidence of it.

What did the JAMA Oncology study find about ultra-processed food and colon cancer? A Harvard and Mass General Brigham study tracking nearly 30,000 women over 24 years found that those who ate the highest levels of ultra-processed food had a 45% higher risk of developing precancerous colorectal polyps compared to those who ate the least. Polyps are the precursor lesion that can develop into colorectal cancer.

Is ultra-processed food linked to other GI cancers besides colorectal? Yes. A Dana-Farber Cancer Institute literature review found that early-onset gastrointestinal cancers broadly — including pancreatic, esophageal, stomach, and appendix cancers — rose by 14.8% between 2010 and 2019, with the youngest groups showing the steepest increases.

What age should I get my first colonoscopy? Current guidelines recommend starting at 45 for average-risk individuals. Recent research published in JAMA Oncology suggests that starting at 40 may reduce colorectal cancer mortality by 39%. If you have a family history of colorectal cancer or polyps, talk to your doctor about starting even earlier.

Do I need to wait for more research before changing my diet? The challenge with diet and cancer research is that a definitive double-blind randomized trial is essentially impossible to conduct ethically. The correlational evidence from large, long-running cohort studies is the best evidence we are likely to ever have — and it consistently points in the same direction. Given that the cost of avoiding ultra-processed food is low and the potential benefit is significant, the precautionary principle applies.

What should I eat instead of ultra-processed food? Whole, single-ingredient foods. Grass-fed beef, pasture-raised eggs, raw dairy, vegetables, fruit, and wild-caught fish. Foods your great-grandmother would recognize. The simplest rule: if it has more than five ingredients or ingredients you can't pronounce, think twice.

Sources

American Cancer Society. Colorectal Cancer Statistics, 2026. CA: A Cancer Journal for Clinicians. https://www.cancer.org/research/acs-research-news/colorectal-cancer-drops-in-older-adults-and-rises-in-young-ones.html

Wang C, et al. Ultra-Processed Food Consumption and Risk of Early-Onset Colorectal Cancer Precursors among Women. JAMA Oncology, 2025. DOI: 10.1001/jamaoncol.2025.4777 https://news.harvard.edu/gazette/story/2025/11/researchers-link-ultraprocessed-foods-to-precancerous-polyps

Chiu HM, et al. Long-Term Effectiveness Associated with Fecal Immunochemical Testing for Early-Age Screening. JAMA Oncology, 2025. DOI: 10.1001/jamaoncol.2025.1433 https://www.ajmc.com/view/starting-colorectal-cancer-screening-at-age-40-cuts-death-risk-by-39-study-finds

Dana-Farber Cancer Institute. Early-Onset Gastrointestinal Cancers Literature Review, 2025. https://www.dana-farber.org/newsroom/news-releases/2025/dana-farber-report-shows-alarming-rise-in-many-gastrointestinal-cancers-in-young-people