e12528 Background: The treatment of male breast cancer (MBC) has been extrapolated from female breast cancer (FBC) because of its rarity despite their different clinicopathologic characteristics. We aimed to investigate the distribution of intrinsic subtypes based on immunohistochemistry (IHC), their clinical impact, and treatment pattern in clinical practice through a multicenter study in Korea. Methods: We retrospectively analyzed clinical data of 248 MBC patients 18 institutions across the country from January 1995 to July 2016. Results: The median age of MBC patients was 63 years (range: 25–102 years). Among the 148 patients that underwent intrinsic subtype classification, 61 (41.2%), 44 (29.7%), 29 (19.5%), and 14 (9.5%) were luminal A, luminal B, HER2, and triple-negative breast cancer (TNBC), respectively. TNBC patients showed inferior survival compared with those with other subtypes. Of the 221 patients with operable breast cancer, 108 (48.6%) received adjuvant chemotherapy and 52 (23.5%) received adjuvant radiation therapy. Most hormone receptor-positive patients (166 patients, 82.6%) received adjuvant endocrine treatment. Five-year completion of adjuvant endocrine treatment was associated with superior disease-free survival (DFS) in patients classified with an intrinsic subtype (hazard ratio [HR] = 0.19, 95% confidence interval [CI] 0.005–0.65, P = 0.008) and in all patients (HR = 0.16, 95% CI 0.05–0.54, P = 0.003). Conclusions: Distribution of subtypes of MBC was similar to FBC and luminal type A was most common. Overall survival tended to be improved for luminal A subtype although there was no statistical significance. Completion of adjuvant endocrine treatment was associated with prolonged DFS in intrinsic subtype classified patients. MBC patients have tended to receive les treatment. MBC patients should be treated with standard guideline as FBC patients receive.