IGF1 and breast cancer: Elevated serum IGF1 levels have been associated with an increased risk of CRC, prostate, and breast cancer [14]. The elevated serum levels of IGF1 in CRC make it possible to identify the components of the IGF system as biomarkers of human CRC predisposition and prognosis [3,8,15]. IGFBP3 has been shown to exhibit direct antiproliferative and pro-apoptotic effects [14].