Bladder carcinoma and other second malignancies after radiotherapy for prostate carcinoma.

Abstract

Radiation therapy (RT) to the pelvis has been associated with an increased risk of bladder carcinoma, as well as other malignancies. However, no controlled studies have previously explored the risk of second malignancies after RT for prostate carcinoma. A retrospective cohort study was conducted utilizing data from the Surveillance, Epidemiology, and End Results Program (SEER) of the U. S. National Cancer Institute from 1973-1990. The standardized incidence ratio (SIR), adjusted for age, was calculated as an estimate of the relative risk (RR) of developing a second malignancy after prostate carcinoma for radiated and nonradiated prostate carcinoma patients separately. The cohort was comprised of 34,889 prostate carcinoma patients who had undergone RT, and 106,872 who had not. After 8 years, the risk of bladder carcinoma was elevated for the RT group (RR 1.5; 95% confidence interval [CI], 1.1-2.0) but not for the non-RT group (RR 1.0; 95% CI, 0.7-1.2). There was an elevated risk of bladder carcinoma for the RT group at 5-8 years as well (RR 1.3; 95% CI, 1.0-1.7). No elevations in risk were observed for rectal carcinoma, acute nonlymphocytic leukemia, or chronic lymphocytic leukemia for either RT patients or non-RT patients. The risk of bladder carcinoma is elevated several years after RT for prostate carcinoma, but this elevation is not dramatic. There is no increased risk of rectal carcinoma or leukemia after this type of radiation exposure.