Rectal cancer deaths among older millennials are accelerating, with growth in mortality far outpacing colon cancer, suggesting primary care doctors should fully investigate early symptoms in patients under age 45, according to a study to be presented at Digestive Disease Week® (DDW) 2026 .
"Colorectal cancer is no longer considered predominantly a disease of older adults," said Mythili Menon Pathiyil, 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."
Researchers analyzed U.S. death records from 1999 to 2023 for adults aged 20–44 from the Centers for Disease Control and Prevention (CDC) WONDER database, calculating annual changes in mortality rates by sex, race and ethnicity, region, and age group. They then applied a machine learning model known as ARIMA to project trends through 2035, assuming current patterns continue unchanged.
The analysis found steadily increasing death rates for colorectal cancer overall, with rectal cancer mortality rising 2 to 3 times faster than colon cancer across every demographic. Among adults ages 35–44, the core of the millennial generation, rectal cancer mortality is projected to escalate through 2035, even as colon cancer mortality in the same age group rises more slowly. Hispanic adults and those living in Western states saw the steepest rise in rectal cancer deaths, with Hispanic adults experiencing the fastest-growing mortality rates of any demographic group.
Pathiyil said the findings support rethinking screening strategies, including greater use of flexible sigmoidoscopy to detect rectal cancers, and promoting increased awareness. She said young adults and primary care providers should pay more attention to symptoms like rectal bleeding and changes in bowel habits, which are often written off as hemorrhoids or other ailments in younger patients.
"It's less about just changing guidelines overnight and more about changing how we think about it, recognizing that colorectal cancer in young adults is no longer rare, and it needs earlier attention," Pathiyil said.
Pathiyil said she undertook the study because she saw a growing number of younger, otherwise healthy patients newly diagnosed with colorectal cancer at advanced stages. She said other research has shown that older patients begin treatment within a month of symptom onset, while it took seven months from the first symptoms to treatment for young adults, a crucial delay.
"Our study shows that rectal cancer is driving much of the increase in colorectal cancers, and it's most likely to worsen over time if we don't change what we are doing right now," Pathiyil said.
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