Background: Hereditary breast and ovarian cancer (HBOC) caused by pathogenic variants in BRCA1/2 genes confers a markedly elevated lifetime risk of ovarian and breast cancers. While risk-reducing salpingo-oophorectomy (RRSO) remains the only proven preventive strategy for tubo-ovarian cancer, public health insurance coverage in Japan currently extends only to breast cancer survivors, leaving unaffected carriers without financial support. Methods: We reviewed the impact of the introduction of public insurance coverage for RRSO at the Cancer Institute Hospital and described our institutional surveillance protocol for BRCA1/2 pathogenic variant carriers who defer RRSO. The protocol incorporates serum CA125 measurement and transvaginal ultrasonography every 3 months, supplemented by endometrial cytology every 6 months. Results: Following the implementation of insurance coverage in April 2020, the annual number of RRSO procedures increased 3.9-fold, with shorter intervals between HBOC diagnosis and surgery. Surveillance identified five cases of ovarian or fallopian tube cancer, two of which were triggered by positive endometrial cytology. Importantly, complete macroscopic resection (R0) was achieved in all cases, despite diagnoses at FIGO stage III. Conclusion: Our experience highlights the clinical utility of integrating endometrial cytology into HBOC surveillance and suggests that surveillance may facilitate R0 resection even in advanced-stage cases. Nonetheless, the current restriction of RRSO insurance coverage to breast cancer survivors imposes significant inequity. Expanding coverage to unaffected carriers is essential for equitable care, timely preventive intervention, and improved oncologic outcomes in Japan.