Clinical, molecular and epidemiological studies have provided emerging evidence of a possible role of obesity, involving complex biological pathways such as the hypothalamic-pituitary-adrenal (HPA) axis, growth factors, the pancreas and the sympathetic nervous system, peptide hormones such as leptin and insulin, and more recently the metabolic syndrome in prostate cancer pathogenesis [6,52-55]. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.