ER expression was inversely correlated with the smallest tumor size (p = 0.009, R−0.365; Spearman test), lower histological grade (p = 0.003, R = −0.31; Spearman test), and a lower Ki67 index (p = 0.01, R = −0.28; Spearman test). This evidence concerns the gene ESR1 and neoplasm.