A Molecular Profiling of Breast Cancer

Despite tremendous advances in breast cancer characterization and therapy over the last 20 years, clinicians still have difficulty accurately predicting the prognosis for individual breast cancer patients. Patients with identical histologic tumor characteristics can have markedly different outcomes in terms of distant metastasis-free and overall survival. Microarray expression profiling is a novel method to further characterize breast cancer tumors at the gene expression level. Breast cancer subtypes have been described which display different clinical behavior. In addition, groups of genes, known as gene-signatures, have been identified which provide more accurate prognostic factors than current clinical and histologic features. Prospective, randomized clinical trials have been conceived regarding two of these signatures (OncotypeDX^™ and MammaPrint®), which are currently available for clinical use. Future clinical decisions may rely on expression profiling of breast tumors.