Colon cancer rates are rising for the first time in 20 years. Here’s who’s most at risk

Colon cancer rates are on the rise after remaining stable for over two decades, according to a new study published in NEJM Evidence. Researchers from the University of Chicago found that the overall incidence rate of colorectal cancer—second leading cause of cancer-related deaths in the U.S.—increased from 36.7 per 100,000 people in 2022 to 38.3 in 2023. This is the first rise in incidence rates for the cancer in more than 20 years, with the age-adjusted rate declining from 55.2 in 2000.

The study, led by Caitlin Murphy, a professor of pediatrics and public health sciences at the University of Chicago, found that the sharpest increase occurred among people between the ages of 45 and 49, with a 13% rise from 2019 to 2023. This surge is likely due to more people in this age group getting screened for colorectal cancer, which earlier detection can help identify the cancer at an earlier stage.

However, the study also revealed a puzzling trend: colorectal cancer rates are still rising among people aged 65 to 69, even as they are largely up-to-date with recommended screening. The researchers are unsure why this is happening and believe that unknown risk factors may be offsetting the gains from screening. They plan to explore environmental chemical exposures as a potential cause, working with a toxicologist from Emory University to test thousands of environmental exposures on organoids—specialized models that can grow colons in a dish.