[Histopathologic diagnosis of luminal and basal type breast cancer]

Despite tremendous advances in breast cancer characterization and therapy over the last 20 years, clinicians still have difficulty to accurately predict the prognosis in individual breast cancer patients. Patients with identical histologic tumor characteristics can have markedly different outcome in terms of distant metastasis-free and overall survival. The most common breast cancer is invasive ductal carcinoma, which is heterogeneous and according to immunohistochemical markers is divided in the luminal and basal type, as also identified by the recent expression profiling method. 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 biological behaviors. In addition, groups of genes known as gene-signatures have been identified, which provide more accurate prognostic factors than current clinical and histologic features. Future clinical decisions may rely on expression profiling of breast tumors.