THE ROLE OF BCL-2 EXPRESSION IN BREAST CARCINOMAS (REVIEW)

The proto-oncogene bcl-2 is demonstrated to block a final common pathw ay leading to apoptosis and is expressed in more than half of human br east cancers. Invasive breast cancer has reduced bcl-2 immunostaining compared with normal breast epithelia and preinvasive breast lesions. As an inhibitor of apoptosis, bcl-2 should correlate with highly aggre ssive tumor biology and resistance to hormonal/ cytotoxic therapy. How ever, high bcl-2 expression has been shown to associate with a number of favorable prognostic factors including ER positivity, PgR positivit y, low histological grade, well-differentiated tumor, absence of c-erb B-2 and p53. Unexpectedly, numerous studies have shown that tumors wit h high bcl-2 expression are more responsive to hormone therapy and hav e more favorable disease-free and overall survival. The clinical signi ficance of bcl-2 in tumorigenesis and prognosis of breast carcinomas f rom the data recently published are reviewed. Its role in modulation o f hormonal/cytotoxic therapy and future directions are also discussed.