We hypothesized from the whole results that the axillary lymph node metastasis process is predominantly related to intrinsic biological properties in the ER negative HER2 negative breast cancer subgroup when stochastic events, tumour size, growth rate and lympho vascular invasion are the main determinants in both the ER positive or the HER2 positive breast cancer subgroups. This evidence concerns the gene ERBB2 and breast cancer.