LEP and neoplasm: Indeed, we and other authors have extensively demonstrated that leptin, mainly produced by adipocytes but also by epithelial tumor cells itself and by other cells within the tumor stroma (i.e., CAFs) [20], is able to affect several hallmarks of breast cancer [21], impacting directly the phenotype of cancer epithelial cells and indirectly the behavior of the tumor microenvironment [22,23,24].