Biomarkers to Evaluate Efficacy of Chemoprevention
Breast cancer chemoprevention studies are in progress with antiestrogens, retinoids and other drugs on preclinical models and on women with increased risk of developing breast cancer. It is still not known whether the above agents are efficacious in individual patients and which are the most reliable biomarkers to be assessed for efficacy. Over the past decade, researchers have developed short-term bioassays for efficacy in animals models of breast cancer that simulate the development and progression of human breast cancer. In these studies, they employed predominantly molecular biomarkers related to cell cycle progression, apoptosis and senescence. Tamoxifen, which has been widely used for treatment and more recently, for the prevention of breast cancer, may differentially affect cell proliferation and apoptosis in mammary tumors and the expression levels of cyclin D1 and cyclin E might also be considered potential intermediate biomarkers of response of mammary tumors to tamoxifen and possibly to other selective estrogen receptor modulators. Other biomarkers are currently under investigation for assessment of the efficacy of various chemopreventive agents.