BOSTON — It was long considered a disease that came with aging, but, increasingly, colorectal cancer is showing up in younger adults in the U.S. That’s one of the primary messages oncologists want to send this March, during Colorectal Cancer Awareness Month.
“Since the mid-1990s, there’s been a documented two percent per year increase in the incidence of this disease in both men and women under the age of 50,” said Kimmie Ng, MD, MPH, associate chief of the Division of Gastrointestinal Oncology at Dana-Farber Cancer Institute. “And this is happening in both colon and rectal cancer -- and again, both in men and women.”
In fact, Ng said the steepest increases in colorectal cancer incidence are happening in Americans in their 20s and 30s. What’s baffling about this development, she said, is that many of those younger patients lead healthy lifestyles.
Excessive consumption of red meat and alcohol, lack of exercise and obesity are all considered risk factors for colorectal cancer.
Ng said some have hypothesized that the rise of the disease in younger adults may have something to do with alterations in the microbiome -- a broad term used to describe the trillions of beneficial microorganisms that normally colonize human bodies -- with most concentrated in the large intestine. Some studies have shown a possible association between antibiotic use and colorectal cancer -- precisely because those drugs can alter intestinal bacterial levels.
“The proximity of these microorganisms to where this cancer develops certainly has suggested that there might be a strong link between the two,” Ng said.
David Thau was diagnosed with colorectal cancer at age 34. He doesn’t recall excessive use of antibiotics during his life. He does remember, however, the day in 2019 when a CT scan finally explained why he’d been feeling run down and out of breath -- and why he was experiencing frequent stomach issues.
“The pain just got so acute, I couldn’t move,” he said. In the days that followed, doctors removed a Stage 3C tumor from Thau’s colon that had nearly blocked passage of stool. That was fortunate cancer did not spread -- but the experience has led him to advocate for screening.
Ng said colonoscopies and other forms of screening can be life-saving.
“We know that if you catch colorectal cancer when it is Stage One or Two, it is highly curable,” Ng said. “When colorectal cancer is caught at a later stage -- for example, Stage 3 or 4, chances of a recurrence and metastasis is much higher.”
Federal figures show a decline in the number of colorectal deaths in those 55 and older between 2000 and 2019. Around the same time, the percentage of Americans staying up-to-date on colonoscopies has risen.
One troubling figure: colorectal cancer deaths went up in those 45-54. Last year, a federal task force recommended lowering the age of first colonoscopy from 50 to 45.
But Ng said there are certain populations that may need the tests even earlier. For example, family history, she said, is an important risk factor -- especially if a close relative has had the disease or has had a tubular adenoma -- the type of polyp that morphs into colorectal cancer.
Unfortunately, that kind of information is often not readily shared in families, Ng suggests.
“Nobody really talks about it,” she said. “You know some of the symptoms associated with developing this disease aren’t the most comfortable to talk about. And there may be a stigma associated with colorectal cancer that prevents people from asking their family if there’s a family history or if there’s a family history of polyps.”
“So we are on a mission to try to raise awareness of this disease in general,” Ng said. “And try to normalize conversations around some of these symptoms. and the topic of family history -- and to raise awareness about the life-saving benefits of screening.”
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