As opposed to physiological levels of insulin (0.5 nmol/L), secreted by the pancreatic β-cells, circulating IGF-1 (20 nmol/L) and IGF-2 (90 nmol/L) can be produced by the liver (under the influence of growth hormone), by malignant tissues themselves, or by their associated stroma; thus, they may stimulate cancers through endocrine, autocrine, or paracrine effects, respectively [17-20]. This evidence concerns the gene IGF1 and cancer.