LEP and breast carcinoma: It was observed that combination therapy involving the blockade of the leptin receptor and treatment with tamoxifen could inhibit proliferation and promote apoptosis in breast cancer cells resistant to tamoxifen, suggesting that the suppression of leptin could be a new means to circumvent resistance to antiestrogenic treatment in breast cancer, because the signaling pathways activated by leptin could directly participate in the cellular response to the chemotherapeutic treatment12.