ERBB2 and neoplasm: At enrolment, all groups of patients were comparable regarding mean age, tumor and nodal stage, histologic grade and classification, HER2 and progesterone receptor status, type of main surgery (mastectomy or breast conserving surgery) and axillar surgery (sentinel node procedure only or axillary lymph node dissection), adjuvant radiotherapy and chemotherapy, and treatment with trastuzumab (p value > 0.05).