Background: HER-2 overexpression is seen in 20% to 30% of invasive female breast carcinomas. Besides being prognostic, HER-2 may also be predictive of response to therapy. Similar studies in male breast carcinoma are lacking. We compared the overexpression and amplification of HER-2 in female and male breast carcinoma.
Design: Formalin-fixed, paraffin embedded archival material from 58 invasive male breast carcinomas and 202 invasive female breast carcinomas were immunostained for HER-2. Scoring was performed according to established guidelines. Each case was also assessed for HER-2 gene amplification by fluorescence in-situ hybridization (FISH) utilizing the PathVysion assay (Vysis corporation, Downers Grove, Illinois).
Results: There were 58 male patients who ranged in age from 38 to 92 years (mean 63). Thirty-five (60%) were T1 lesions and 23 (40%) were T2 lesions. Twenty-five patients (43%) had positive lymph nodes. One (1.7%) of the 58 cases showed 3+ staining of HER-2. The remaining 57 cases did not show overexpression. There was no amplification of the HER-2 gene in any of the cases. There were 202 female patients who ranged in age from 26 to 96 years (mean 52). In all, 129 (64%) were T1 lesions, 61 (30%) were T2 lesions, and 13 (6%) were T3 lesions. Fifty-two (26%) showed positive staining with HER-2 (44 cases 3+, 8 cases 2+). The remaining 150 (74%) did not show overexpression. There was amplification of HER-2 gene in 55 (27%) of the cases. Two of the cases negative by FISH were 3+ positive by IHC.
Conclusions: HER-2 is overexpressed in approximately 27% of female breast carcinomas. A high level of correlation is demonstrated between IHC and FISH techniques. Gene amplification of HER-2 does not play a role in male breast carcinoma. The rate of single-copy overexpression of HER-2 appears identical in male and female breast carcinoma.