Nobody in their 20s, 30s or 40s gets colorectal cancer, right? Wrong. The truth is that colorectal cancer has been on the rise in young adults for years and is now the leading cause of cancer deaths overall in this age group. "We are seeing a clear uptick in colorectal cancer in younger generations," says Haddon Pantel, MD, a Yale Medicine colorectal surgeon. In early 2023, the American Cancer Society (ACS) reported that 20% of diagnoses in 2019 were in patients under age 55, which was about double the rate in 1995, and rates of advanced disease increased by about 3% annually in people younger than 50. In 2026, an ACS study published in the Journal of the American Medical Association (JAMA) showed that while overall cancer mortality decreased by 44% in people younger than 50 in the United States between 1990 and 2023, colorectal cancer increased by 1.1% each year since 2005, going from the fifth leading cause of cancer deaths in this age group to the first. Nobody knows for sure why colorectal cancer numbers are rising in young people. Sedentary lifestyle, overweight and obesity, smoking, heavy alcohol use, low-fiber, high-fat diets or diets high in processed meats, and other environmental factors have all been associated with the disease. Family history of colorectal cancer or polyps, and conditions such as inflammatory bowel disease are also risk factors. Yale MedicineColorectal Cancer: What Millennials and Gen Zers Need to...Colorectal cancer is on the rise among people younger than 50. Yale Medicine physicians say people as young as 20 need to know the signs and symptoms.