Rectal cancer risk 70% higher in PCa patients who undergo radiation

Rectal cancer risk is 70% higher in men who undergo radiation for prostate cancer than those who opt to have surgery to treat the cancer, according to a study to be published in the April issue of Gastroenterology.

The rectal cancer risk associated with radiation for prostate cancer is similar to the risk posed by having a family history of rectal cancer, researchers said.

"Men who have had prostate radiation should be aggressively monitored for rectal cancer starting 5 years after treatment," said lead author Nancy Baxter, MD, PhD, University of Minnesota Cancer Center, Minneapolis. "This is the first time rectal cancer risk associated with prostate radiation has been quantified, and these findings may also have implications for patients treated with radiation for other pelvic cancers."

Dr. Baxter and colleagues used data from the Surveillance, Epidemiology, and End Results (SEER) Registry to evaluate the effect of radiation on development of cancer in the rectum. The retrospective, population-based study included more than 85,000 men, ranging in age from 18 to 80 years.

Since the study results are based on men who were treated for prostate cancer prior to 1995, the risk of developing cancer may be reduced by the evolution of radiation delivery techniques. However, researchers said that with today's technologies some portions of the rectum might still receive a high dose of radiation. Therefore, the risk of rectal cancer may still be substantial. Investigators recommend that prostate cancer patients be told the risk of developing rectal cancer when considering a course of treatment.