IGF1 and obesity due to melanocortin 4 receptor deficiency: The underlying mechanism driving the obesity–breast cancer link are not fully understood, but obesity-associated alterations [72], including hyperinsulinemia and increased availability of IGF1, are associated with increased cell proliferation, migration and metastasis, insensitivity to antigrowth signals, induction of angiogenesis, and exacerbating the adipose-tissue-mediated chronic inflammation [73].