Risk classification and clinical management of the DNA variant of unknown significance(VUS)in BRCA 1/2 remains unestablished. The Japanese hereditary breast and ovarian cancer(HBOC)consortium and myriad genetics reported that the VUS rate of BRCA is 6.5% in Japanese patients, but is <2% in the USA. The types of mutation supposedly differ between Asian and European ethnicities. Breast-conserving therapy(BCT)is not recommended in HBOC breast cancer, according to the 2017 Japanese guidelines by the Ministry of Health, because of the risk of ipsilateral breast recurrence(IBR)and carcinogenesis by radiation. In our hospital, we recommend an initial mastectomy and breast reconstruction with an implant for patients with HBOC breast cancer, considering future surgery on the contralateral side and symmetry of the reconstructed breast. However, the risk of IBR after BCT is not significantly high in patients with HBOC breast cancer, and BCT is a reasonable option even for definite HBOC breast cancer under low risk conditions. Hence, BCT is feasible for treating breast cancer in carriers of VUS following decision-making and informed consent from the patients.