gms | German Medical Science

Introduction: Male breast cancer is a rare disease which accounts for approximately 1% ofall breast carcinomas. The incidence is increasing in the last decade. Due to the lack of clinical trials and prospective studies diagnostic strategies and therapeutic standards are related to female breast cancer guidelines. Retrospective studies and molecular analyses revealed distinct differences. However, it is still unclear if male breast cancer is an independent tumor entity or a subset of female breast cancer. In our retrospective study, cytogenetic and moleculargenetic examinations were performed on male breast carcinomas and correlated to clinicopathological parameters.

Material and Methods: 96 primary male breast cancer cases were analysed. Clinical data and histopathological features were available. Using Tissue Microarrays immunohistochemical staining ofhormone receptors, HER-2/neu, p53, Ki67 and Cyclin D1 was evaluated. HER-2/neu amplification was examined by fluorescence in situ hybridization. In 39 cases comparative genomic hybridization (CGH) was performed to analyse cytogenetic changes. The results were statistically correlated to clinicopathological parameters and compared to female breast cancer data from the literature.

Results: Clinicopathological data of the male breast carcinomas showed a significant proportion (66/96) of caseswith advanced tumor stages (pT3-4). The overall survival time was 72 months. Immunohistochemical staining revealed that 89/96 (92,7%) cases were hormone receptor positive. 11 cases (11,5%) were HER-2/neu positive which was confirmed by HER-2/neu gene amplification.35 male breast carcinomas were Ki67 positive (36,5%), Cyclin D1 positivity was found in 48 (50,0%) cases and 8/96 (8,3%) cases showed p53 overexpression. No correlations were observed between expression of different biological markers and clinicopathological parameters. In CGH analysis, the average number of chromosomal aberrations was 4,7. The median number of chromosomal gains was 3,8and 2,4 losses were found in average. Over-representations occurred predominantly at chromosomal regions 1q (46.2%), 8q (46.2%), 16p (35.9%), 17q (35.9%), Xq (28.2%), 20q (25.6%), and Xp(17.9%). Losses were most frequently found at 8p (35.9%), 16q (28.2%), 13q (28.2%), 6q (17.9%), 11q (17.9%), and 22q (17.9%).

Discussion: Compared to female breast carcinomas expression of hormone receptors was increased. In contrast, HER-2/neu positivity was lower. No significant differences were found in Ki67, Cyclin D1 and p53expression. CGH analysis revealed a lower number of chromosomal aberrations. Regarding female breast cancer, both entities share a common pattern of chromosomal imbalances. Expression of tumorbiological parameters and number and pattern of chromosomal aberration in male breast cancer are comparable to well differentiated early female breast cancer.