Risk-reducing mastectomy and salpingo-oophorectomy in women with hereditary breast and ovarian cancer: a single-institute experience following coverage by Japanese national medical insurance.

Risk-reducing mastectomy (RRM) and risk-reducing salpingo-oophorectomy (RRSO) are preventive options for women with hereditary breast and ovarian cancer (HBOC). The Japanese national medical insurance began covering RRM and RRSO for patients with HBOC in April 2020. We retrospectively analyzed 59 individuals with pathogenic germline variants (PGVs) from 55 families diagnosed with HBOC between 2010 and 2024 to assess the prevalence of RRM and RRSO after April 2020. The median age at diagnosis was 50 years. Ten individuals (16.9%) were diagnosed before April 2020, whereas 49 (83.1%) were diagnosed afterward. PGVs included BRCA1 (28 individuals) and BRCA2 (31 individuals). The most common cancer was breast cancer (74.6%), followed by ovarian (13.6%), and pancreatic cancer (3.3%); 15.3% had no cancer history. RRM was performed in 19 of 41 individuals (46.3%), with the highest rate observed among BRCA1 PGV individuals (55.0%). RRSO was conducted in 30 of 41 individuals (73.1%), with higher rates among BRCA1 and BRCA2 PGV individuals. None of the individuals without a history of breast and/or ovarian cancer underwent these procedures. The median age was 50 for RRM and 49 for RRSO. Most surgeries (64.7% for RRM and 76.0% for RRSO) occurred within a year of genetic testing. Multivariate analysis showed that breast cancer history was strongly associated with RRM. National insurance coverage has enhanced access to genetic testing and preventive surgeries, with 46.3% and 73.1% undergoing RRM and RRSO, respectively. However, individuals without a cancer history remain underrepresented.