Indeed, expression of such genes may contribute towards limiting maximal anti-tumour activity of these agents in ER-positive breast cancer cells [29,30] as is suggested by the ability of tamoxifen and further anti-oestrogens to promote early induction of EGFR and HER2 [5], genes linked to tamoxifen resistance and an adverse cell phenotype. This evidence concerns the gene EGFR and neoplasm.