Gallen International ExpertConsensus includes treatment algorithms based on the classification of breast cancer subtypesaccording to the immunohistochemistry of estrogen receptor (ER), progesterone receptor (PR),HER2, and Ki67 expression.6,7 We previously identified differences in prognosis among breast cancerpatients with five distinct immunohistochemical subtypes.8 Here, ERBB2 is linked to breast carcinoma.