Second Primary Cancer Risk of Radiation Therapy After Radical Prostatectomy for Prostate Cancer: An Analysis of SEER Data

Objectives: To determine the incidence of second primary cancer (SPC) and primary pelvic late SPC/radiation-induced SPC after radical prostatectomy and radiation. Methods: A total of 228 235 prostate cancer patients in the 1973-2002 Surveillance, Epidemiology, and End Results database were studied. The age-adjusted estimates of SPCs was calculated. Competing risk multivariable Cox proportional hazards regression analysis was adjusted for age at diagnosis, race or ethnicity, and radiation and was used to evaluate the effect of treatment on SPC. Results: The overall incidence of SPC was 8.4%. The most frequent pelvic SPCs were bladder (2303 cases), rectum or rectosigmoid junction (1006 cases). The most frequent nonpelvic SPCs were bronchus and lung (4131 cases), colon (2665 cases), and skin (1769 cases). The absolute risk of developing a second malignancy was 1747 cases per 100 000 in the "Radical surgery and x-ray treatment" group and 1581 in the "radical surgery" group. With regard to late primary pelvic SPC, a higher age-adjusted rate of 374 cases per 100 000 was seen in the radiated group. Conclusions: Radiation after radical surgery increased late primary pelvic SPC. No increases were seen in secondary pelvic or extrapelvic SPCs.