Uterine cancer (Ut Ca) following risk-reducing salpingo-oophorectomy (RRSO) in women with BRCA mutations (BRCA+): A multicenter, prospective study.

1504 Background: While RRSO is key in management for BRCA+ women, concomitant hysterectomy is not standard. Here we estimate the risk of Ut Ca in BRCA+ women following RRSO and examine the distribution of specific histologic subtypes. Methods: BRCA+ women from 9 centers who underwent RRSO with retention of the uterus were prospectively followed from latest of ascertainment, BRCA testing, or RRSO. Censoring occurred at hysterectomy, Ut Ca diagnosis, last follow-up or death. Expected cancer incidence was determined using age and race specific SEER data, adjusted for prevalence of hysterectomy. Ut Ca were categorized into endometrioid endometrial cancer (E-EC) [e.g. endometrioid, adenocarcinoma NOS], serous endometrial cancer (S-EC) [e.g. serous, undifferentiated], and sarcoma. The observed-to-expected (Obs/Exp) ratios and lower limit of 97.5% CI were analyzed using 1-sided Poisson distribution test. Results: 1083 BRCA+ women were followed for a median 5.2 years. 8 incident Ut Ca were observed [4.2 Exp; Obs/...