Rectal Cancer Might Occur After Radiation for Prostate Cancer

Proctitis can occur after external-beam radiation therapy for prostate cancer. These researchers sought to determine whether radiation therapy also increases risk for rectal cancer.

In the National Cancer Institute's SEER cancer registry (which covers about 14% of the U.S. population), 85,000 men who were diagnosed with prostate cancer from 1973 through 1994 underwent surgery only (55,000) or external-beam radiation therapy (30,000). A total of 1437 colorectal cancers (267 rectal) were diagnosed at 5 or more years after prostate cancer treatment. In analyses adjusted for potential confounding variables, patients who underwent radiation therapy were at significantly higher risk for developing rectal cancer (hazard ratio, 1.7) than were patien…