This cancer is on the rise in young adults — and doctors don’t know why

Colon cancer rates are rapidly rising in younger people. (Photo: Getty Images)
Colon cancer rates are rapidly rising in younger people. (Photo: Getty Images)

When you think of colon cancer, you probably assume it’s a grandparent’s disease. But alarming new research shows that rates are rapidly rising in younger adults. If you were born in 1990, you have twice the risk of colon cancer and four times the risk of rectal cancer compared to someone born around 1950, according to a 2017 study published in the Journal of the National Cancer Institute.

“We’re all baffled and perplexed by this,” says Mark Pochapin, MD, professor of medicine and director of the division of gastroenterology and hepatology at NYU Langone Health.

Even more concerning, the study found that people younger than 55 are nearly 60 percent more likely to be diagnosed with late-stage disease than older adults. “When a 25-year old complains of blood in their stool or of a sudden change in their bowel habits, their primary care physician rarely thinks it could be cancer and doesn’t offer screening tests that can diagnose the problem, like a colonoscopy,” explains Edith Mitchell, MD, program leader of gastrointestinal oncology at the NCI-designated Sidney Kimmel Cancer Center at Jefferson Health in Philadelphia. “As a result, they’re not diagnosed until a much later stage. But it’s amazing how many young patients we now have. I would say that about 40 percent of my patients now are below age 50.”

Colon or rectal cancer in younger adults is often attributed to other risk factors such as inflammatory bowel disease (Crohn’s disease or ulcerative colitis) or an inherited genetic syndrome like Lynch syndrome. But experts say that for many of the younger people they see, there’s no clear reason why it occurs.

“The rise in colorectal rates in younger adults has been parallel to the rise in the obesity epidemic, so it’s reasonable to think that that’s a factor,” explains David Liska, MD, a colorectal surgeon at the Cleveland Clinic. “Many of the risk factors for obesity are also risk factors for colon cancer, including a high fat diet that’s high in red meat and low in vegetables, as well as being sedentary. But I’m seeing a lot of younger patients who are at a normal weight and have a healthy lifestyle, so there have to be other reasons.”

One theory is that changes in the microbiome — the bacteria in your digestive tract — may be a factor, too. “Younger adults may have been exposed to a lot of antibiotics as children, and eat more processed foods than their parents did,” notes Pochapin. “That, in turn, may have altered their gut bacteria in ways that encourage cancer cells to grow.”

Here’s what you can do to protect yourself:

Know your family history

Up to 35 percent of people under the age of 35 who are diagnosed with colon cancer have a genetic mutation, compared to about five percent of all colorectal cancer cases, according to a 2015 study published in the Journal of Clinical Oncology. “There’s more and more evidence that colorectal cancer in younger people may be genetically different than colorectal cancer in older adults,” adds Liska. The two main familial conditions that raise risk of colorectal cancer are familial adenomatous polyposis (FAP), where hundreds of polyps cover the inner lining of the colon, and Lynch syndrome. But there may be many other genetic mutations that raise risk of colon cancer that we don’t yet know about, notes Liska.

If you have a family history of either colon cancer or colon polyps, then you should consult with a genetic counselor, advises Joy Larsen Haidle, spokesperson for the National Society of Genetic Counselors. They can determine whether it makes sense for you to have genetic testing to see if you have one of the common colorectal cancer-causing genetic mutations.

Stay at a healthy weight

People who are overweight before age 30 have a higher chance of developing colon cancer later in life, according to a 2018 review published in the International Journal of Cancer. Another 2018 study published in JAMA Oncology found that women in their 20s, 30s and 40s who were either overweight or obese had up to twice the risk of developing colorectal cancer before age 50, compared to women of normal weight.

It’s also important to eat a diet rich in fruits, vegetables, and whole grains and one that’s low in red or processed meats, adds Pochapin. These steps have all also been shown to lower colon cancer risk, as well as getting regular exercise, not smoking and limiting alcohol.

Make sure you’re up to date on screenings

The American Cancer Society now recommends all adults begin colon cancer screening at age 45. While the gold standard is a colonoscopy — a test where your doctor uses a flexible, lighted tube to check for polyps in your rectum and colon while you’re under sedation — you can also do an at-home screening test, known as a fecal immunochemical test (FIT), which checks for hidden blood in your stool, on your own. (Just keep in mind that if the test comes back positive, you’ll need to have a colonoscopy.)

But if you have a family history of colon cancer, you may need to start even earlier: “We recommend then beginning at age 40, or 10 years younger than when the youngest person in the family was diagnosed with cancer,” explains Pochapin.

Listen to your body

Most younger adults diagnosed with colon cancer have it first develop in the lower part of the bowel, which usually presents as rectal bleeding, notes Pochapin. “Any rectal bleeding should be taken seriously and requires a colonoscopy,” he stresses.

But you should also be alert for any changes in bowel function — that means diarrhea or constipation that lingers for more than a few days. “One of the most common signs is stool getting thinner and narrower, almost like a pencil caliber,” adds Pochapin. “This is because the colon cancer starts narrowing down the inside of the bowel.”

If you feel like your doctor is ignoring your concerns, get a second opinion. “My 15-year-old patient complained of symptoms for months and was told repeatedly that they were just due to her starting menstruation,” says Mitchell. “It wasn’t until she ended up in the ER requiring immediate surgery that she was properly diagnosed.”

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