Colorectal cancer rates have declined in both men and women since 1975, particularly in those over age 75 years, but there has also been a significant increase in the incidence among those aged 20-34 years, a retrospective cohort study shows.

Researchers analyzed data from 393,241 patients registered in the Surveillance, Epidemiology, and End Results ( SEER ) colorectal cancer registry from 1975 to 2010, finding the overall, age-adjusted incidence of colorectal cancer decreased by 0.92% during that time.

They observed a steady decline in the incidence of colorectal cancer in the over 50 age group, with a 1.15% decrease in those aged over 75 years, while in those aged 20-34 years, there was a nearly 2% increase, according to data published online November 5 in JAMA Surgery ( doi:10.1001/jamasurg.2014.1756 ).

“At the present rate, the incidence rate for young patients with newly diagnosed colon or rectal cancer will nearly double by 2030, while it will similarly decline by more than one-third among patients older than the screening age of 50 years,” wrote Dr. Christina E. Bailey of the University of Texas M.D. Anderson Cancer Center, Houston, and colleagues.

The study was supported by grants from the National Institutes of Health and National Cancer Institute. There were no conflicts of interest declared.