The contribution of molecular markers to the prediction of response in thetreatment of breast cancer: A review of the literature on HER-2, p53and BCL-2

Background: The selection of therapies for breast cancer is today based on prognostic features (chemotherapy, radiotherapy), hormone receptor status ( hormonal therapy) and HER-2 status (trastuzumab therapy). HER-2, p53 and BC L-2 are tumour-related proteins that have the potential to further improve individualisation of patient management, by predicting response to chemothe rapy, hormonal therapy and radiotherapy. Materials and methods: This paper reviews the rationale for the use of thes e proteins as predictive factors, as well as the published literature addre ssing the use of each one to predict response to hormonal therapy, chemothe rapy and radiotherapy. Results: HER-2, p53 and BCL-2 remain inadequately assessed as predictive fa ctors in breast cancer. HER-2 evaluation is required for the selection of p atients for trastuzumab (Herceptin (R)) therapy, as trials of this therapy have been limited to HER-2 overexpressors. HER-2 overexpression may be pred ictive of resistance to hormonal therapy. Anthracyclines are effective ther apy for breast cancer regardless of HER-2 status, but patients whose tumour s overexpress HER-2 appear to receive the greatest relative benefit from th is therapy. Studies of HER-2 as a predictor of response to CMF and to radio therapy are inconclusive at this time. No data yet exist to support the use of p53 or BCL-2 as predictive factors in the therapy of breast cancer. Conclusions: At this point in time, there is inadequate evidence to support the use of HER-2, p53 or BCL-2 to guide the selection of hormonal therapy, chemotherapy or radiotherapy for breast cancer.