Radiation therapy does not increase rectal cancer risk

Men who receive radiation therapy for prostate cancer are not at any appreciable increased risk of developing rectal cancer compared with those not given radiation therapy, according to a recently published study by Canadian researchers.

The researchers evaluated the records of 237,773 men who had prostate cancer. Of them, 33,841 received radiation therapy, 167,607 had their prostate removed, and 36,335 received neither treatment.

On an initial simple evaluation, the team found that rectal cancer developed in 243 men who received radiation (0.7%), 578 men treated with surgery (0.3%), and 227 men who were given neither treatment (0.8%). Once the team had adjusted for age difference, they could not find any significant increased risk of rectal cancer among the groups (Int J Radiat Oncol Biol Phys 2006; 65:661-8).

“Rectal cancer from other causes is frequent enough in our population to obscure any small incidence of radiation-induced cancer,” said Wayne S. Kendal, MD, PhD, of Ottawa Hospital Regional Cancer Centre in Ontario. “I hope that the results of the study will help men with prostate cancer and their families put these risks in their proper prospective, and not let their concerns about rectal cancer dissuade them from choosing radiation therapy as a treatment for this disease.”