731 Gene Copy Number Alterations in Male Breast Tumors

Background: To date knowledge about specific biological and molecular characteristics of male breast cancer (MBC) is almost not existent, thus it’s difficult to identified different subclasses that have both biological and clinical relevance, as observed in female breast cancer (FBC). Gene copy number (GCN) alteration is a common mechanism of oncogenic activation in breast cancer (BC). We aimed to analyze GCN variation of genes involved in cell proliferation, hormone metabolism and cell cycle control, that are know to play a relevant role in FBC as prognostic factors and as possible targets for therapy and that may play also a role in MBC. In particular we analyzed GCN alterations of EGFR, PIK3CA, ESR1, CCND1 and SULT1A1, in order to identified new biomarkers in MBC that may allow to better understand the pathogenesis of MBC and can lead to the identification of MBCs subgroups with specific clinical-pathologic characteristics. Material and Methods: GCN alterations of EGFR, PIK3CA, ESR1, CCND1 and SULT1A1 were evaluated on a series of 100 MBC tumors characterized for BRCA1/2 mutations, the major genetic risk factor, and for relevant clinicalpathologic features. The analysis was performed by TaqMan assay using Real-Time PCR. Results: Overall, PIK3CA showed an amplification frequency of 8.5%, EGFR of 9%, CCND1 of 15% and SULT1A1 of 4.2%, whereas SULT1A1 and ESR1 were deleted with a frequency of 14%. Significant statistically association emerged between PIK3CA amplification and HER2 expression (p = 0.023), EGFR amplification and ER− status (p = 0.01), HER2 and MIB1 expression (p = 0.026 and 0.013) and T4 (p = 0.027). A significant statically association emerged also between ESR1 deletion and ER− status (p = 0.02), CCND1 amplification and HER2 (p = 0.017) and MIB1 expression (p = 0.03) and between SULT1A1 deletion and ER− status (p = 0.015) and G3 (p = 0.03). These data suggest that EGFR, CCND1 and SULT1A1 alterations may be linked to an aggressive phenotype in MBC. Conclusions: Our results indicate that the presence of EGFR, PIK3CA, ESR1, CCND1 and SULT1A1 GCN alterations can lead to the identification of MBCs subgroups with specific clinical-pathologic characteristics that can be useful in clinical management of MBC patients. Study supported by AIRC (IG 3713).