Second cancer (SCa) risk among patients (pt) treated with abdomino-pelvic radiation (XRT) for epithelial ovarian cancer (EOC).

e16535 Background: Prior studies suggest a survival benefit of adjuvant abdomino-pelvic XRT for the treatment of low stage, non-serous EOC. However, the long-term risk of a SCa from XRT is unknown. We examined the relationship between XRT use and the risk of SCas in a population-based cohort of EOC pt. Methods: We determined the rates of SCa in a previously described cohort of stage I-III (microscopic residual only) EOCs, diagnosed between 1984-2008 and treated with adjuvant chemotherapy +/-XRT(45 Gray to abdomen and pelvis) at any of 5 regional Cancer Centers in British Columbia. SCas were any non-skin cancer(ca) diagnosed > / = 12mo after the primary EOC. The site of SCa relative to the XRT field was determined by a radiation oncologist(in-field/field border/out-of-field)(CH). Cox regression accounting for age, stage and histotype comparing XRT vs. no XRT was used to determine the hazard for developing SCa as the event of interest. Competing risk analysis was carried out looking at either SCa or death d...