Yang et al. used image analysis to compare ER expression in epithelium located near breast carcinomas to the expression levels in terminal ductal lobular units located distant from the tumor based on TMA sections.23 They found significantly higher levels of ER expression near the tumors but the level of expression did not correlate with ER expression in the carcinoma cells, arguing against a positive field effect by the tumor. Here, ESR1 is linked to carcinoma.