Prognosis
Currently traditional prognostic factors such as tumor size, lymph node status and histological grade are used to give a very broad estimation of prognosis, for example, using the Nottingham Prognostic Index (NPI), Adjuvant! Online, which are commonly employed tools. As a major turning point, the concept of personalized treatment plans using gene assays of tumor samples from individual patients has evolved.
With increasing research determining patient specific genetic signatures, individual gene assays are now available. The Oncotype DX® test (Genomic Health, CA, USA) is an example of a gene assay used for patients with specific tumor biology: ER positive, HER2 negative and lymph node negative. These tools have the ability to determine prognosis, and also benefit of adjuvant therapies, for example, chemotherapy in patients with ER-positive tumors in the Oncotype DX model.
Classification of breast cancers according to subtypes has now become important and the St Gallen Consensus on adjuvant systemic therapies is now based on such system. This approach broadly recommends systemic therapy based on subtypes. Luminal A disease generally requires only endocrine therapy, Chemotherapy is generally added for most luminal B cases. Chemotherapy and trastuzumab are considered for HER2-positive disease. Patients with basal cancers might require different chemotherapy regimens.