Abstract PS3-01-29: The Impact of Oophorectomy on Breast Cancer Survival in Patient with a BRCA1 Mutation

Abstract It has been established that preventive bilateral salpingo-oophorectomy (BSO) provides a survival advantage for women with breast cancer and a BRCA1 mutation, if done before or after diagnosis. It is of interest to see if the benefit of BSO varies according to the age at breast cancer diagnosis, age at oophorectomy and ER-status of the tumour. We are following a cohort of 2904 women with breast cancer and a BRCA1 mutation for survival. We excluded 256 women who had an oophorectomy before breast cancer. We also excluded women with metastatic cancer, with cancer diagnosed after age 70, and with cancers for greater than 10cm in size, leaving 2541 women for the present analysis. Of these, 1498 had an oophorectomy after breast cancer (mean time from diagnosis to BSO 2.3 years). We followed the women from diagnosis to death for a mean of 9.5 years (range 0.1 to 27.5 years). 289 women died of breast cancer. We conducted a survival analysis (Cox model) including BSO as a time-dependent variable, adjusting for tumour size (<2cm, 2-5cm, 5-10 cm) and lymph node status (positive/negative). Hazard ratios were for breast cancer survival. Of those women diagnosed with breast cancer before age 50, BSO was associated with a hazard ratio of 0.53 (95%CI 0.40 to 0.69). Of those women diagnosed with breast cancer after age 50, BSO was associated with a hazard ratio of 0.30 (95%CI 0.17 to 0.53). Of all women diagnosed with ER-positive breast cancer, BSO was associated with a hazard ratio of 0.57 (95%CI 0.35 to 0.90). Of those women diagnosed with ER-positive breast cancer before age 50, BSO was associated with a hazard ratio of 0.74 (95%CI 0.42 to 1.30). Of those women diagnosed with ER-positive breast cancer after age 50, BSO was associated with a hazard ratio of 0.26 (95%CI 0.10 to 0.65). Of all women diagnosed with ER-negative breast cancer, BSO was associated with a hazard ratio of 0.45 (95%CI 0.33 to 0.60). Of those women diagnosed with ER-negative breast cancer after age 50, BSO was associated with a hazard ratio of 0.32 (95%CI 0.15 to 0.69). In summary BSO after breast cancer is associated with improved survival across all age groups, with the possible exception of young women with ER+ breast cancer. Citation Format: S. Narod, J. Lubinski, S. Wong, J. Soukupova, R. Bernstein, R. Fruscio, J. Plichta, M. Lee, A. Irmejs, G. Evans, J. Ngeow, N. Tung, K. Metcalfe, P. Sun. The Impact of Oophorectomy on Breast Cancer Survival in Patient with a BRCA1 Mutation [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 PS3-01-29.