Introduction/Background Bilateral salpingo-oophorectomy offers the greatest risk reduction for ovarian cancer in high-risk women with an identified BRCA germline mutation. The aim of this study was to define the incidence of precursor lesions and cancer after RRSO.

Methodology We retrospectively reviewed 71 BRCA-mutated patients who underwent RRSO from 2012 to 2017. All cases were examined according to the protocol for Sectioning and Extensively Examining the FIMbriated End (SEE-FIM).

Results The median age at RRSO was 49.9 years. BRCA 1 mutation was detected in 46/71 (64.8%) patients, BRCA2 mutation in 25/71 (35.2%) patients. 50/71 (70.4%) patients had breast cancer. BRCA1 breast cancer was more frequently high grade (G3) and showed a strong association to triple negative phenotype (p=0.001), high TILs (tumor-infiltrating lymphocytes), and aberrant expression of p53 (p=0.01). Occult invasive gynecological cancer was detected in two patients: a tubal high grade serous carcinoma in a BRCA2+ patient and an ovarian low-grade endometrioid carcinoma in a BRCA1+ patient. 5 (7%) STIC (Serous Tubal Intraepithelial Carcinoma), 5 (7%) STIL (Serous Tubal Intraepithelial Lesion) and 13 (18.3%) SCOUT (Secretory Cell Outgrowth) were detected. 10 patients had endometriosis and benign ovarian lesions were found in 17 cases. The detection rate of STIC/STIL or invasive cancer was 16.9% (12/71). Tubal lesions were more common in BRCA2 mutation carriers (68% vs. 39%).

Conclusion In our institution, a rigorous surgical protocol with meticulous pathologic review at RRSO yielded an overall detection rate of 9.8% for occult gynecological carcinoma in BRCA mutation carriers.

Disclosure Nothing to disclose.