Risk of breast cancer after ovarian cancer in germline BRCA1/2 heterozygotes

Breast cancer risk after ovarian cancer in germline BRCA1/2 heterozygotes remains uncertain, with a recent large multicentre international study reporting lower-than-expected incidence in the first decade after ovarian cancer diagnosis (Apostol et al. 2026). We re‑evaluated our previously published regional cohort of 701 women with ovarian cancer and a germline BRCA1/2 pathogenic or likely pathogenic variant, restricting the analysis to those tested after ovarian cancer diagnosis and without prior breast cancer, to minimise ascertainment and survivor bias. In our refined cohort of 406 women, 19 breast cancers occurred over 1340.97 person‑years, giving an annual incidence of 1.42% (1.60% for BRCA1 and 1.14% for BRCA2). Incidence was lowest within the first 5 years (0.88%/year) and increased beyond 10 years (1.89%/year). These estimates align closely with those reported recently by Apostol et al. Breast cancer incidence after ovarian cancer is low in the first decade but may rise thereafter. These findings support reassurance during early survivorship while recognising that long‑term survivors may still consider risk‑reducing mastectomy.