A 2023 study by He W et al. examined 170 ER-positive gynecomastia patients (91 on tamoxifen, 79 undergoing surgery), finding that the co-expression of estrogen and androgen receptors significantly influenced outcomes, with tamoxifen effectively inhibiting breast tissue proliferation in receptor-high cases [13,38]. This evidence concerns the gene ESR1 and Gynecomastia.