SUMMARY: BACKGROUND: Bilateral male breast cancer (MBC) is relatively rare. CASE REPORTS: We report 2 bilateral nonsynchronous MBC cases. Second cancers developed during endocrine therapy with selective estrogen receptor modulators (SERM) after the initial surgeries. Since their second surgeries, both patients continued treatment with another SERM, because their second cancers were also hormone receptor-positive. We discuss the endocrine therapy in men based on a review of the literature. CONCLUSIONS: Adequate treatments for early MBC are still controversial. Aromatase inhibitors (AI) are not as effective in men as in women. We consider the higher androgen levels in men to be a major reason for AI not being as effective as expected, i.e. the hormonal environment is very different from that in women. Thus, different approaches are needed for MBC. With further investigation, it is hoped that methods of achieving maximal AI efficacy for MBC will be established.
SUMMARY: BACKGROUND:Bilateral male breast cancer (MBC) is relatively rare. CASE REPORTS: We report 2 bilateral nonsynchronous MBC cases. Second cancers developed during endocrine therapy with selective estrogen receptor modulators (SERM) after the initial surgeries. Since their second surgeries, both patients continued treatment with another SERM, because their second cancers were also hormone receptor-positive. We discuss the endocrine therapy in men based on a review of the literature. CONCLUSIONS: Adequate treatments for early MBC are still controversial. Aromatase inhibitors (AI) are not as effective in men as in women. We consider the higher androgen levels in men to be a major reason for AI not being as effective as expected, i.e. the hormonal environment is very different from that in women. Thus, different approaches are needed for MBC. With further investigation, it is hoped that methods of achieving maximal AI efficacy for MBC will be established.