This hormone, is involved in the normal development of mammary glands and lactation [165], but also stimulates cell proliferation, and invasiveness in breast cancer tissue [166], where its levels are higher than in normal breast tissue [167] The stimulatory effects of leptin on BC growth occurs in different ways including the activation of the ER [158], upregulation of VEGF, an increase in aromatase activity, or increase in telomerase activity [168,169,170,171]. Here, LEP is linked to breast cancer.