Biomarker Endpoints for Early-Phase Cancer-Prevention Studies

Breast cancer is the most common malignancy among women in the US, and prevention of this disease is therefore a major public health concern. Chemoprevention with anti-estrogens, including tamoxifen, raloxifene, and exemestane, has been shown to reduce the incidence of hormone receptor (HR)-positive breast cancer. However, breast cancer chemoprevention uptake has been poor and effective chemopreventive agents for HR-negative tumors are yet to be identified. A priority for breast cancer prevention research is improving the efficiency of chemoprevention trials by use of intermediate biomarkers correlated with breast cancer risk. This review provides an overview of the literature on breast-imaging-based, tissue-based, and circulating biomarkers which have been associated with breast cancer risk by observational studies and are being investigated as intermediate endpoints for early-phase chemoprevention trials.