ERBB2 and breast cancer: The relationship among protein expression, clinicopathological factors (e.g., human epidermal growth factor receptor 2 (HER 2), tumor size, tumor-node-metastasis (TNM) classification), and overall survival of the breast cancer tissues were analyzed using Pearson’s χ-square (χ2) test, Fisher’s exact test, multivariate logistic regression and Kaplan–Meier survival analysis.