The standardization of the HER2 score and recent changes in therpeutic modalities points to che need for reevaluation of the role in recently diagnosed breast carcinoma. A multicenter, retrospective study of 1794 primary breast carcinoas diagnosed in Italy in 200/2001 and scored in HER2 four categories accordin to immunohistochemistry was conducted. Ductal histotpe, vascular invasion, grade, MIB1 positivity, estrogen and progesterone receptor expression differed significantly in HER2 3+ tumors compared with the other categories. Her2 2+ tumors almost showed values intermediate between those of the negative and the 3+ subgroups. The characteristics of HER2 1+ tumors were found to be in between those of HER2 0 and 2+ tumors. With a median follow-up of 54 months , HER2 3+ status was associated with higher relapse rates in node-positive subgroups, while HER2 2+ only in node positive. Analysis of relapses according to type of therapy provided evidence of responsiveness of HER2-positive tumors to chemotherapy, expecially taxanes. The present prognostic significance of HER2 is correlated to receptor expression level and points to the need to consider HE2+ and HER2 3+ tumors as distinct diseases with different outcomes and specific features.
