In the METABRIC and TCGA cohorts, subtype 2 was significantly associated with large tumour size (both p < 0.0001), high histological grade (both p < 0.0001), ER negativity (both p < 0.0001), PR negativity (both p < 0.0001) and HER2 positivity (both p < 0.0001; Table 3). This evidence concerns the gene ERBB2 and neoplasm.