[Predicting response to therapy in breast cancer]

Molecular staging of breast cancer with microarray technologies leads to different gene expression profiles distinguishing 4 special groups: luminal A and B subtype, HER2 subtype and basal subtype. These 4 groups show a different prognosis as well as different behaviours and responses to adjuvant therapy. The development of gene expression profiles to classify breast cancer may contribute to the targeted institution of adjuvant therapies. Especially the 21-gene recurrence score (Oncotype DX) and the 70-gene profile (Mamma-print) have become intensively examined prognostic and predictive tools. As chemotherapy is an integral component of adjuvant therapy in early breast cancer but estrogen-receptor-positive breast cancer is the most common type, patient selection for adjuvant chemotherapy is of particular interest. In instances when the benefit from chemotherapy seems modest, there is a decision making tool beside traditional histopathological parameters that might provide additional objective prognostic and predictive information. Those genomic decision making approaches may yield more rational treatment choices and may keep patients from systemic treatment modalities of lower value.