Recently, a study reported an association between serum levels of estradiol and gene expression of trefoil factor 1 (TFF1), growth regulation by estrogen in breast cancer 1 (GREB1), PDZ domain containing 1 (PDZK1) and progesterone receptor (PGR) in ER+ breast carcinomas [10]. The gene discussed is ESR1; the disease is breast carcinoma.