DEMOGRAPHIC DISASTER

Nearly half of colorectal cancers now occur in younger patients

- NINA AGRAWAL

early half of all new colorectal cancer cases now occur in adults younger than 65, signalling a major shift in the demographics of the disease, according to data published last week by the American Cancer Society.

"This was always a disease that was grandpa's disease," said Dr William Dahut, chief scientific officer of the American Cancer Society. But among people 65 and older, colorectal cancer rates have been steadily declining since the mid-1980s, thanks in large part to widespread screening that can catch precancerous polyps and early-stage cancers.

By contrast, studies in recent years have shown colorectal cancer rates on the rise among adults younger than 50. The new paper showed that rates among adults ages 50 to 64 also increased between 2013 and 2022 and that rates of rectal cancer in particular climbed among all ages combined after years of decline.

Researchers have observed what's called a "birth-cohort effect" with colorectal cancers, meaning that successive generations — in this case, beginning with those born in the 1950s — are showing progressively increased risk. People born in 1990 are twice as likely as those born in 1950 to develop colon cancer and four times as likely to develop rectal cancer.

"This isn't necessarily an age-specific thing — this is a generational thing," said Andreana Holowatyj, an assistant professor of haematology and oncology at Vanderbilt University Medical Center in Tennessee who wasn't involved in the study.