863 Risk-reducing bilateral salpingo-oophorectomy in BRCA1/2 pathogenic variant carriers: histopathological results and clinical outcomes. a retrospective monocentric study

Introduction/Background Risk-Reducing Bilateral Salpingo-Oophorectomy (RRSO) is the most effective strategy for reducing ovarian cancer risk in women with an inherited BRCA1 or BRCA2 mutation. The presence of occult carcinomas is reported at variable rates (2–12%), with limited literature on the incidence of high-grade serous tubal precursor lesions (STIC, STIL, and SCOUT) in BRCA mutation carriers. Methodology This retrospective study aims to assess pathological findings in a cohort of BRCA1/2 mutation carriers who underwent RRSO between 2002 and 2022. Demographic characteristics and clinical outcomes were correlated. Inclusion criteria for prophylactic treatment included asymptomatic women with negative gynecological evaluation (pelvic examination, transvaginal ultrasound) within 3 months before RRSO and a pathogenic variant in BRCA1/2. Results The final cohort included 744 BRCA1/2 mutation carriers. Eleven cases of invasive occult tumors were identified, the pathological reports showed STIC in 13/774 cases (1.7%), STIL in 15/774 (1.9%), and SCOUT in 5/774 (0.6%). Immunohistochemical analysis revealed a p53 signature in 60/774 (7.8%) cases. Peritoneal washing was positive for atypical cells in 2/772 cases. Histological examination of endometrial biopsies identified one case of occult endometrial neoplasia out of 764 samples. Patients underwent a mean follow-up of 47.75 months (range 0–221.27). At the last follow-up, 708 patients were NED, 40 were AWD, and 15 were deceased due to ovarian cancer. No patient developed primary peritoneal tumors during follow-up. Conclusion Our 20-year study reveals a low risk of diagnosing occult cancer in BRCA-mutated patients undergoing RRSO. Histological precursors did not indicate a heightened risk for developing primary peritoneal tumors. Disclosures All authors declare no conflicts of interest.