Expression of Bcl-2 protein in human primary breast carcinomas and its correlation with multifocality, histopathological types and prognosis

The Bcl-2 gene product prevents programmed cell death (apoptosis) and possibly promotes tumour development. This protein has mainly been demonstrated in the cytoplasm of various normal and neoplastic cells, including normal mammary epithelia and breast carcinomas. The aim of this retrospective study was to correlate the immunohistochemical expression of Bcl-2 protein with the multi-unifocality and the histology of the two main types of breast carcinoma. We used monoclonal antibody 124 to investigate Bcl-2 expression in paraffin sections of 62 primary breast carcinomas. Bcl-2 expression was associated mainly with this lobular carcinoma. High Bcl-2 protein positivity was found in this type, and was statistically significant in comparison to the level of Bcl-2 in ductal, NOS carcinomas (lobular versus ductal, NOS, P < 0.0001). In the entire group, including all histological types, Bcl-2 expression was higher in multifocal tumours (P = 0.005). Statistical significance (P<0.03) was also found within the group of ductal, NOS cases, showing that Bcl-2 protein expression is associated with multifocality, irrespective of the histology of breast carcinomas. No definite association between Bcl-2 expression and prognosis was found. Our results suggest that Bcl-2 protein plays some role in the development of multifocality in breast carcinomas.