Evaluation of ERBB2 gene status and chromosome 17 anomalies in male breast cancer

Male breast cancer (MBC) is an uncommon neoplasm that shares several biologic characteristics with its female counterpart. In the latter, abnormalities in the expression and/or copy number of the ERBB2 gene are present in 10% to 30% of invasive carcinoma and behave as poor prognostic markers. ERBB2 abnormalities have also been reported in MBC, yet at lower frequency, but their prognostic significance remains controversial. Furthermore, no study has addressed the impact of chromosome 17 abnormalities in MBC survival. In this study, the ERBB2-gene status (overexpression and amplification) and chromosome 17 numerical abnormalities were investigated in a series of 50 archival cases of MBC. The results, together with patient's age, histologic grade, pathologic stage, and estrogen receptor status were correlated with overall survival. ERBB2-protein overexpression was present in 7 cases (14%), ERBB2-gene amplification in 4 (8%), and aneuploidy of chromosome 17 in 12 cases (33.3%). The pathologic stage, ERBB2 overexpression and ERBB2 amplification were significantly correlated with overall survival (P=0.002, 0.016, and 0.009, respectively). No correlation was observed between chromosome 17 aneuploidy and overall survival. Therefore, despite their low incidence in MBC, expression abnormalities of ERBB2 behave, together with the pathologic stage of the tumor, as predictors of overall survival, akin to what has been reported for its female counterpart.