BACKGROUND: Women with ovarian cancer (OC) and a pathogenic variant in the BRCA1 or BRCA2 genes are at increased risk of developing breast cancer (BC). Evidence for long term outcomes in these patients who undergo bilateral risk reduction mastectomy (RRM) after ovarian cancer is sparse. The aim of this study was to analyse the long-term breast cancer-related outcomes of patients who have been diagnosed with ovarian cancer and found to have BRCA1 or 2 pathogenic variants. METHODS: Local approval was granted. The hospital clinical genetics database was interrogated to identify women who have been diagnosed with OC and a germline BRCA1/2 pathogenic variant between January 2010-March 2020. Patient demographics, OC treatment as well as any BC related information was analysed. RESULTS: 148 women were diagnosed with OC and a pathogenic variant in BRCA1/2 in the study period. 47 patients were excluded as they did not have treatment at our institution. 101 patients were included. The median age at diagnosis of OC was 52 years (IQR 46-61). Eighty-four (82 %) were FIGO stage 3 or 4 OC. At a median follow-up of 63 months (IQR 39-94), 55 (54.4 %) women had been diagnosed with a recurrence of ovarian cancer and 38 (37 %) women have died. Twenty-one (21 %) women were diagnosed with BC. 13 (12.9 %) had BC before OC, 4 after and 4 synchronous with OC. Of the remaining patients who did not have BC, 6 underwent bilateral risk reduction mastectomy (RRM) after treatment for OC. DISCUSSION: Risk of disease recurrence and death due to stage 3 and 4 ovarian cancer remained high in this time period. RRM can be undertaken in carefully selected patients, however we would recommend reserving this for women who have favourable OC disease prognosis.