Nationwide survey of hereditary breast and ovarian cancer-related clinical practice in gynecologic oncology in Japan: a joint study by the Japan Society of Gynecologic Oncology (JSGO) and the Japan Society of Obstetrics and Gynecology (JSOG).

To evaluate the current status of hereditary breast and ovarian cancer (HBOC)-related clinical practice in Japan, including genetic testing, risk-reducing surgery, and surveillance systems, and to identify institutional gaps and unmet needs. A nationwide questionnaire survey was conducted between February and April 2024 targeting 647 Japan Society of Obstetrics and Gynecology-affiliated training facilities and gynecologic oncology centers. Institutional-level data on genetic testing, homologous recombination deficiency (HRD) testing, risk-reducing salpingo-oophorectomy (RRSO), postoperative management, surveillance practices, and healthcare infrastructure were collected. Responses from 248 institutions (response rate, 38.3%) were analyzed descriptively. BRCA1/2 genetic testing was performed in 83% of institutions, and HRD testing using the myChoice® CDx system in 87%. However, only 30% offered universal BRCA1/2 testing for ovarian, fallopian tube, or peritoneal cancer, and testing indications varied widely. Genetic counseling resources were uneven, with 29% lacking on-site genetic specialists, driven mainly by institutional characteristics rather than geographic location. RRSO was performed in 50% of institutions, predominantly laparoscopically. While management of occult carcinoma after RRSO was largely consistent, postoperative management of serous tubal intraepithelial carcinoma (STIC) and positive peritoneal cytology varied substantially. Over 70% of institutions reported a need for expanded insurance coverage for genetic services and preventive care. Although HBOC-related genetic testing and preventive strategies are widely implemented in Japan, this nationwide survey revealed critical structural and evidence gaps, particularly in institutional capacity and the management of evidence-limited scenarios such as STIC, underscoring the need for system-level improvement.