Abstract PS3-05-09: Approaches to Breast Cancer Risk Management in Ovarian Cancer (OC) Patients Harboring Germline BRCA1/2 Mutations (gBRCA1/2mut)

Abstract Introduction: Patients with ovarian cancer carrying germline BRCA1/2 mutations or pathogenic variants (gBRCA1/2mut) have a significantly increased lifetime risk of developing breast cancer. While the treatment of ovarian cancer is usually the primary clinical focus, proactive strategies to reduce future breast cancer risk - including intensified surveillance, risk-reducing mastectomy, and chemoprevention - are essential components of comprehensive care. Given the evolving therapeutic landscape and improving survival outcomes in ovarian cancer, individualized approaches to breast cancer risk management are becoming increasingly relevant in this high-risk population. Our objective was to evaluate and describe breast cancer risk management strategies in OC patients carrying gBRCA1/2mut. Methods: A retrospective review of medical records was conducted for patients with OC and gBRCA1/2mut, focusing on breast cancer risk - reduction strategies. Results: A total of 88 patients with OC and gBRCA1/2mut were identified. Among them, 66 (75%) had BRCA1mutations and 22 (25%) had BRCA2 mutations. Twenty-three patients (26%) had a previous history of breast cancer prior to the BRCA1/2 mutation diagnosis; of these, 16 (18%) were treated with lumpectomy, 6 (26%) with mastectomy, and 1 (4%) with adenomastectomy. Regarding axillary management, 11 (48%) underwent sentinel lymph node biopsy, 9 (39%) axillary dissection, and in 3 cases (13%) axillary status was unknown. Fifty-one patients (58%) had a family history of breast cancer.After a median follow-up time of 70 months, only 12 patients (13%) underwent risk-reducing breast surgery: 8 (67%) underwent bilateral adenomastectomy, 3 (25%) bilateral mastectomy, and for 1 patient the chosen procedure was not specified. Among 13/88 patients with stage I-II ovarian cancer, 5 underwent prophylactic mastectomy, compared to 7 out of 75/88 patients with stage III-IV disease. Of the 12 patients who underwent prophylactic mastectomy, only 3 had relapsed ovarian disease - all of whom had advanced-stage cancer at diagnosis. Overall survival from the time of ovarian cancer diagnosis was 94.2 months. Most patients (65%) opted for active surveillance every 6 months, with magnetic resonance imaging (MRI), ultrasound, and mammography. Imaging findings classified as BI-RADS 3 were identified in 9 patients (16%), and BI-RADS 4/5 in 8 patients (14%). A total of 6 patients (10%) were ultimately diagnosed with breast cancer, half of which were luminal subtype tumors. Among these 6 cases, half were clinical stage IA, two were stage IIA, and one was stage IIIA breast cancer. Conclusion: In this cohort of OC patients with gBRCA1/2mut, the majority underwent imaging-based surveillance, with a relevant proportion presenting with suspicious findings and subsequent breast cancer diagnoses. These findings highlight the importance of individualized counseling and the integration of breast cancer prevention into the long-term management of ovarian cancer survivors with gBRCA1/2 mutations, particularly in the context of improving survival outcomes. Citation Format: D. Guilherme de Albuquerque e Rodrigues de Sousa, L. Soares, T. Saruwatari, A. Cicilini, J. Casali da Rocha, S. Sanches, A. Gadelha, F. Makdissi, G. Baiochi, B. Tirapelli, F. Leite, M. Sonagli, R. Cagnacci, S. Caputo Durand, A. Favarin, B. Rossi, G. Molin, A. da Costa, E. dos Santos. Approaches to Breast Cancer Risk Management in Ovarian Cancer (OC) Patients Harboring Germline BRCA1/2 Mutations (gBRCA1/2mut) abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS3-05-09.