It has been demonstrated that leptin treatment interferes with the antagonistic effects of tamoxifen in ERα-positive breast cancer cells [32,33] and the synergy between the leptin/Ob-R/STAT3 signaling pathway with the HER2 receptor induces tamoxifen resistance in breast cancer cells through differential regulation of apoptosis-related genes [35]. Here, STAT3 is linked to breast carcinoma.