ESR1 and neoplasm: Nevertheless, ER expression in normal epithelium has not been shown to vary with tumor grade.19 Tissue samples for our TMA control cases were collected more than 30 years ago and passage of time has been shown to reduce antigenicity of formalin-fixed paraffin-embedded tissue.28 If there was any loss of antigenicity in these cases however, it would only further strengthen our findings, as the TMA control cases still showed higher ER expression overall than was seen in normal epithelium of low ER positive cases.