The immunohistochemical panel is prognostic and predictive, and should be performed for all in situ or invasive breast carcinomas, as it allows approximating the molecular classification of invasive breast cancer, classifying breast tumors as luminal-like (tumors with hormone receptors, estrogen and progesterone positive), HER2-like (with expression of the HER2 membrane protein) and basal-like (tumors lacking hormone receptors and the HER2 membrane protein). The gene discussed is ERBB2; the disease is breast neoplasm.