Higher circulating IGF-1 level was associated with higher risk of prostate cancer (Chan et al, 1998), lung cancer (Yu et al, 1999), colorectal cancer (Ma et al, 1999), premenopausal breast cancer (Toniolo et al, 2000) and younger aged ovarian cancer (Peeters et al, 2007). Here, IGF1 is linked to prostate cancer.