From conventional pathologic diagnosis to the molecular classification of breast carcinoma: are we ready for the change?

Breast cancer is the most frequent malignant tumor in women and the diagnosis, prognosis and therapeutic strategy are based on the pathologic report. In last years, it was shown that conventional pathologic diagnosis brings few data about prognosis and tells nothing about the response of the tumor to specific therapy. In an effort to improve the molecular characterization of breast cancer, gene profile analysis was performed in a large number of cases. Based on this analysis, there were characterized five molecularly different subclasses: basal-like, luminal type A and B, HER-2, and unclassified. It was shown that prognosis and response to adjuvant therapy is significantly different in these five subtypes. Immunohistochemistry was demonstrated to be a good and acceptable surrogate of the gene analysis. A panel of antibody that includes estrogen receptors (ER), progesterone receptors (PR), Her2 protein, cytokeratin 5 (CK5), epidermal growth factor receptor (EGFR), p53 mutation, and Bcl-2 expression, can discriminate between these five molecular subclasses. In the present review there are presented the main characteristics of the molecular subclasses, the relationships with the conventional pathologic classification, critical problems of the molecular classification and their impact on prognosis and therapy.