Using a multivariate logistic regression model adjusted for these correlated variables (age, marital status, fertility history, cancer stage, tumour size, histology, lymph node invasion, and the expression of HER-2), older age, tumour size of 2-5 cm, stage 2-stage 3 cancers, and positive for HER-2 were significant independent predictors of mastectomy uptake (see Table 3). This evidence concerns the gene ERBB2 and cancer.