21180 Background: Recently, inmunophenotypic characterization methods have allowed identification of female breast carcinomas into separate groups showing different behaviour and response to therapy: luminal A phenotype (RE +, HER2-neu - ), luminal B (RE +, HER2- neu + ), basal like (RE -, HER2-neu - ). In this study, we used immunohistochemistry to investigate the inmunophenotypic profile distribution of male breast cancer. Methods: all the male breast cancers were obtained from the files of the Departments of Pathology of Hospital Río Carrión in Palencia, Spain, since 1996. A total of 9 cases were reviewed to confirm the diagnosis and to characterize each tumour. The following CK immunohistochemistry was performed: 8/18 and 5 (Dako, Carpinteria, CA, USA) in a Dako autostainer. ER was interpreted as positive if > 10% of the cells were staining. Normal skin and tonsils were used as positive controls for the CK and a known breast cancer for the ER immunohistochemistry. Results: five cases expressed RE and were HER2-neu negative, so they have a luminal-A phenotype. The four cases that expressed the luminal-B pehnotype expressed RE and HER2-neu; we demonstrated gene amplification of the HER-neu gene using fluorescent in situ hybridisation (FISH) in those cases. Respect the CKs profile, all cases were positive for CK 8/18 and negative with CK 5, vimentin and p63, characteristic of luminal-like CK expression profile, according wiht the literature. Conclusions: this is the first case series of male breast cancer patients that provides inmunophenotypic profile data on this rare disease in only one center in Spain. We comunicate that the vast majority of these tumours express the phenotype of luminal-like CKs. None of our patients were basal-like tumours. The percentage expression of Her-2 parallels the finding in female breast cancers and this should be analysed for its predictive significance, according to new specific biological treatments. No significant financial relationships to disclose.
Fulvestrant and male breast cancer: a case series