Background: Male breast cancer is an uncommon disease often discovered in advanced stage; thus, in the setting of metastatic adenocarcinoma, breast origin must be taken to account. Breast markers as NY-BR-1, GATA-3, mammaglobin, and BRST-2 are established tools for labelling primary and metastatic female breast cancer; however, none of them has been sufficiently studied in male breast cancer. The aim of this study was to analyze the expression of these markers in male breast cancer.
Materials and methods: Thirty consecutive cases of male breast cancer and eight loco-regional metastases were re-revaluated, assembled in tissue micro array (TMA), and stained with immunohistochemistry (IHC) for NY-BR-1, GATA-3, mammaglobin, and BRST-2. The IHC stains were scored either positive or negative. In addition, concordant expression patterns of primary tumors and matched metastasis were noted.
Results: 30 of 30 (100%) primary tumors and 8 of 8 (100%) metastases were positive for NY-BR-1. 30 of 30 (100%) primary tumors and 6 of 8 (75%) metastases were positive for GATA-3. 22 of 30 (73.3%) primary tumors and 6 of 8 (75%) metastases were positive for Mammaglobin. 18 of 30 (60%) primary tumors and 5 of 8 (62.5%) metastases were positive for BRST-2. Differences in staining percentage were not significant with Fisher's exact test.
Conclusion: We found a high sensitivity for all the markers analyzed. Moreover, the expression of NY-BR-1 and GATA-3 seemed the most effective for labelling male breast cancer in primary and metastatic setting.
Keywords: GATA-3; Metastatic male breast cancer; NY-BR-1; Primary male breast cancer.