Colorectal Cancer Screening Shifts as Cases Rise in Adults Under 50

Rising colorectal cancer rates in younger adults are prompting earlier screenings, with colonoscopy offering both detection and prevention.

Rising colorectal cancer rates in adults under 50 are changing how doctors approach screening and prevention, explained Dr. Usman Shah, medical oncologist at Overlook Medical Center.

Screening now begins at age 45 for average-risk adults, while those with family history or other risk factors may need to start earlier. Symptoms like blood in stools, black-colored stools, changes in bowel habits or unexplained iron deficiency should prompt medical evaluation.

Shah noted that colonoscopy is especially valuable because it not only detects cancer early but also prevents it by removing precancerous polyps. He added that lifestyle factors such as eating more fiber and limiting red meat and alcohol can also lower risk.

CURE: How are rising colorectal cancer rates in adults under 50 changing the way that clinicians approach screening and prevention?

Shah: We have to be more aware of this increasing risk in a very young population. It's in a group where we have not historically had to worry about cancer rates, but over the last 15 years, we've definitely seen an uptick in young patients getting cancer. That was certainly a strong contributing factor to the recommendations around screening changing from age 50 to 45. That's not to say we aren’t seeing patients even at younger ages — we are — but that's not the general population risk. Still, we are definitely seeing some concerning findings even in younger patients.

What symptoms or risk factors should younger adults be aware of that might indicate a higher need for early screening?

That's a two-part question, so I'll break it down into both: what are the symptoms and signs to look for, and who should be screened at earlier ages. Historically, if you saw a young patient with blood in their stools, you would most appropriately chalk that up to hemorrhoids. That’s not unusual, and even now, most patients in their 30s or 40s with blood in the stool are not going to have cancer — it’s usually a benign cause. But now that incidence is increasing, we have to pay more attention. Any blood in the stools or black-looking stools should at least warrant an evaluation by a doctor.

Other concerning signs include changes in bowel habits, like new constipation or diarrhea, or an increase in frequency of bowel movements where none existed before. A change in the caliber of the stool — not just bowel habits — can also be concerning. Sometimes patients come to medical attention because of new iron deficiency, with or without anemia, and that can be a clue that blood is being lost somewhere. That also warrants evaluation.

If you have known genetic risk factors, those can indicate the need for screening even earlier than 45. It’s important to remember that 45 is the recommendation for average-risk individuals, not high-risk individuals. High-risk people may need to start earlier. For example, if you have a first-degree relative — like a sibling or parent — with colon cancer, you should get screened 10 years earlier than the age of their diagnosis. If your dad had colon cancer at 50, you should be screened by 40 at the latest.

In terms of prevention, we also have to think about things we can control, like activity levels, diet and environmental exposures. A diet rich in fiber can decrease the risk of developing colon cancer and also decrease the risk of recurrence for people already diagnosed. That’s not a short-term diet but a lifestyle change of incorporating more fiber.

We also know that red meat, especially cured red meats, increase the risk of colorectal cancer. Alcohol also increases risk. That doesn’t mean they must be completely avoided but knowing they are bona fide risk factors can help people make more informed choices.

How does earlier detection through colonoscopy or other screening methods affect treatment options and long-term outcomes for patients?

That's a really important question to make sure folks understand. Screening has two potential benefits. One is early detection: if you diagnose colon or rectal cancer at an earlier stage, the prognosis is much better. The other is prevention. Most colorectal cancers begin as benign polyps that can turn into cancer over seven to 10 years. If we intervene on that polyp by removing it during colonoscopy, we can decrease the risk of that cancer ever developing. Colonoscopy serves both as early detection and prevention. Other less invasive or noninvasive methods can provide early detection but not prevention.

What barriers still exist that prevent adults aged 45 to 49 from getting screened, and how can patients overcome them?

Some recent studies have suggested two groups are less likely to be screened, though the numbers were small. One group is people without insurance, who are not getting screened at the recommended ages. The other correlation, though not causation, is between lower levels of education — like not graduating high school — and lower screening rates. That highlights the need to reach patients across all educational demographics, not just a specific subset.

Transcript has been edited for clarity and conciseness.

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