ERBB2 and neoplasm: Overall, there were no statistical differences between PMR values in tumour tissue and clinicopathological factors (tumour size and stage, presence of axillary metastasis, histological grade, expression of ERs and HER2 or p53 status), with the exception of the expression of PR, for which a statistical trend toward higher methylation levels in PR-negative breast tumours was observed (P=0.075; Mann–Whitney).