Molecular profiling of breast cancer

Breast cancer is now considered a heterogeneous and phenotypically diverse disease. Molecular profiling is used in clinical practice in 2 broad categories: (1) characterization of breast cancers beyond the standard histopathologic features such as tumor grade, histologic subtype, and biomarker profile for prognostic information; and (2) prediction of response to therapy and clinical outcome. This article addresses the importance and application of molecular subtype analysis, and provides an in-depth analysis of the clinical application of the molecular prognostic indices for ductal carcinoma in situ, node-negative invasive breast cancer, and node-positive invasive breast cancer.