Breast cancer: New molecular classification

Despite using histological and immunohistochemical criteria, we are unable to reflect the heterogeneity of breast cancer. In 2012 METABRIC analyzed the genomic and transcriptional architecture of 2000 breast cancers. Molecular subtypes were found to be highly implicated. Such is the importance of molecular biology that, in AJCC-TNM8 (2017), prognostic groups based on biomarker expression (ER, PR, HER2, and Ki67) were incorporated. These groups complement the traditional classification and add a biological approach to the existing purely anatomical one. We have analyzed the METABRIC study, emphasizing the new line of research it contributed. We did an exhaustive literature search in the main databases, obtaining the articles presenting the METABRIC results. We broke down the 10 recently discovered integrative clusters, their genetic variations and their implication for our clinical practice. We found that the current classification of breast cancer is not enough accurate, the inconsistencies of which are explained by the integrative clusters. They lay the foundation for a new classification or for refining existing subtypes.(c) 2021 SESPM. Published by Elsevier Espana, S.L.U. All rights reserved.