It is taking nearly seven months for younger adults to begin treatment after their first warning sign of colorectal cancer, compared to just one month in older patients—a delay that doctors now say is quietly costing lives.

New research to be presented at Digestive Disease Week 2026 reveals a troubling shift. Once considered a disease of ageing populations, colorectal cancer—especially rectal cancer—is rising sharply among adults under 45, with death rates increasing far faster than expected.

“Colorectal cancer is no longer considered predominantly a disease of older adults,” said Mythili Menon Pathiyil, a gastroenterology fellow at SUNY Upstate Medical University and lead author of the study. “Rectal cancer, especially, is becoming a growing problem in younger individuals, and we need to act early to reverse this trend.”

The study analysed more than two decades of US mortality data from the Centers for Disease Control and Prevention database, tracking adults aged 20 to 44. Researchers then used a predictive method called ARIMA—essentially a statistical tool that uses past patterns to forecast future trends—to estimate what lies ahead. The results are stark. Rectal cancer deaths are rising two to three times faster than colon cancer across all groups, with the steepest increases seen in adults aged 35 to 44.

Doctors say the real danger lies in missed warning signs. Symptoms such as rectal bleeding or changes in bowel habits are often dismissed. “Written off as haemorrhoids or other ailments,” as Pathiyil noted, these early signals rarely trigger urgent testing in younger patients.

Rectal cancer begins in the last part of the large intestine, close to the anus, while colorectal cancer is a broader term covering cancers of both the colon and rectum. Detecting it early can be as simple as a flexible sigmoidoscopy—a quick procedure that uses a thin tube with a camera to check the lower bowel. Yet awareness remains low.

Clinicians report seeing more young, otherwise healthy individuals arriving with advanced disease. “It’s less about just changing guidelines overnight and more about changing how we think about it,” Pathiyil said. "Recognising that colorectal cancer in young adults is no longer rare, and it needs earlier attention.”

If current trends continue, deaths will keep climbing through 2035. For doctors and patients alike, the message is blunt: if there is blood, do not ignore it—and do not assume it is harmless.