IGF1 and prostate cancer: Prospective studies have shown that higher circulating concentrations of insulin-like growth factor 1 (IGF-1), insulin-like growth factor 2 (IGF-2), and insulin-like growth factor binding protein-3 (IGFBP-3) are associated with an increased risk of prostate cancer, colorectal cancer, and premenopausal breast, and ovarian cancer (Lukanova et al, 2002; Renehan et al, 2004).