Management of hereditary breast and ovarian cancer

Hereditary breast and ovarian cancer (HBOC) syndrome represents 5−10% of all breast cancers. In Japan, the HBOC syndrome is frequently diagnosed in patients with breast cancer. Therefore, a treatment strategy combining a plan for existing breast cancer and for reduction of future breast and ovarian cancer risk is necessary. Breast cancer risk-reducing management involves three options—surveillance, chemoprevention, and risk-reducing mastectomy (RRM). RRM can prevent >90% of new breast cancers. Ovarian cancer risk management options are more limited, and risk-reduction salpingo-oophorectomy is the only option since there is no proven effective early detection method available. The local recurrence rate following breast-conserving surgery in BRCA1/2 mutation-associated breast cancer is not significantly higher than that in sporadic breast cancer. Furthermore, there is no difference in prognosis between surgical methods. Clinicians should inform patients that there are no data on long-term monitoring and fully discuss risks of re-developing breast cancer with patients when choosing the surgical method. In HBOC, BRCA1/2 mutations lead to failure of double-strand DNA break repair, with poly ADP-ribose polymerase (PARP) playing an important role in single-strand DNA nick repair. Use of PARP inhibitors in HBOC prevents DNA repair (synthetic lethality) leading to cell death. This review summarizes management of the HBOC syndrome based on recent evidence.