Colon Cancer Rates Rising for Americans Under 50

Trend runs counter to steady declines among older people

Issue 26 Winter/Spring 2016

Increased adherence to colon cancer screening guidelines has significantly reduced the rate at which Americans aged 50 and older develop the disease.

However, the generation behind them may not be faring so well. A recent study finds the rate of colon cancer for people in their 20s, 30s, and 40s is on the rise.

The study, published in the Journal of Adolescent and Young Adult Oncology, examined data on more than 230,000 cases of colon cancer recorded in the California Cancer Registry between 1988 and 2009.

It found that in absolute terms, the odds of a person under 50 getting colon cancer is still very small – less than 1 case per 100,000 people for people in their 20s, and around 4 cases per 100,000 for people in their 30s.

That’s compared to more than 94 cases per 100,000 people in their 60s, the study authors noted.

However, researchers led by Dr. Jason Zell, of the University of California Irvine Medical Center, also detected a troubling trend.

While rates of colon cancer for people over 50 charted steady declines during the study period, the rate increased by between 3 to 5 percentage points every 2 years for men aged 20 to 49.

And for certain subgroups of women, the rate of increase was even higher – for example, a nearly 6 percent biannual rise in incidence for white women in their 30s, and a nearly 8 percent biennial increase for Hispanic women in their 20s.

Zell’s team note that the last statistic is especially intriguing, since Hispanics typically tend to have lower colon cancer incidence relative to other groups.

Why is colon cancer rising among younger Americans? Speaking with HealthDay, Zell said the answer remains unclear.

"What I can say is that we need more awareness of the trend among both patients and doctors,” he said. “Because at this point, key symptoms among young adults, like blood in the stool, weight loss or other complaints, are often ignored."

Current guidelines recommend that colon cancer screening – including colonoscopy – begin at age 50 for people at average risk for the disease. And people younger than 50 with a family history of colon cancer should get screened earlier, experts say.

However, Zell’s group pointed to a 2013 study that looked at 180 colon cancer patients under the age of 50. It found that only 8 percent of them had a prior family history of the disease.

According to Zell, all of this means that “we need to do a much better job at early-age detection. Because another thing we observed is that those young adults who get colon cancer have a higher stage of cancer at diagnosis. And that has terrible implications when we look at survival."

According to the American Cancer Society, colorectal cancer remains the third most common cancer diagnosis, with over 133,000 new cases detected each year. Nearly 50,000 Americans will lose their lives to the disease in 2015, making it the number two cancer killer, after lung cancer.