Clinico-pathological and molecular subtypes of male breast carcinoma according to immunohistochemistry

Male breast carcinoma is a rare condition, but with a trend of increase frequency. In our study, we investigate the clinico-pathological features and overall survival at 35 male cases of primary invasive breast carcinoma correlated with molecular subtypes defined by immunohistochemical profile.

Based on immunohistochemical expression profiles of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 (HER2) and Ki67, EGFR and CK5/6, the male breast cancers were classified into the following molecular subtypes: Luminal A, Luminal B, HER2+, triple negative and unclassified.

In our study, we identified 65.7% as Luminal A subtype and 28.6% as Luminal B subtype. The difference was represented by two (5.7%) cases of triple negative subtype, but due to low number of patients, no correlations or prognostic significance could be assessed in these cases. No HER2 or unclassified subtypes were identified.

Luminal A tumors are the most frequent subtype in MBC, with a better outcome than Luminal B subtype. We recorded high levels of ER and PR expression, which predict a better response to adjuvant hormonal therapy. At the time of diagnosis, most of the patients were aged and with an advance clinical stage, this requiring implementation of screening programs and increase education of population in order to an early detection.