ESR1 and neoplasm: The generation of receptor expression heterogeneity may be related to the heterogeneity and the polyclonal nature of tumor tissues, clonal selection of tumor cells, tissue fixation, antigen repair, differences in staining methods, pathologists’ subjective judgment of staining results, and previous treatment (6–9) A meta-analysis showed that ER was 3-54% inconsistent, PR 5-78%, and HER2 0-34% inconsistent (10).