Circulation insulin-like growth factor peptides and colorectal cancer risk: an updated systematic review and meta-analysis.

Insulin-like growth factor peptides, play an important role in regulating cell growth, differentiation, and apoptosis, which has been demonstrated to promote the development of cancer. The purpose of our study is to assess the association between circulation insulin-like growth factor peptides and colorectal cancer (CRC) risk. We searched Medline, EMBASE, OVID and Web of Science and picked up epidemiological studies that satisfied our inclusion criteria. A meta-analysis of 19 epidemiological studies containing 5,155 cases and 9,420 controls related with the association of circulation insulin-like growth factor peptides and CRC risk was carried out. Meta-analysis showed that high level IGF-I and IGF-II significantly increased CRC risk, (OR = 1.25, 95% CI: 1.08-1.45 for IGF-I; OR = 1.52, 95% CI: 1.16-2.01 for IGF-II; OR = 0.85, 95% CI: 0.70-1.03 for IGFBP-1; OR = 0.77, 95% CI: 0.41-1.43 for IGFBP-2 and OR = 0.88, 95% CI: 0.71-1.10 for IGFBP-3). Subgroup analysis showed that the increased cancer risk by IGF-I was more distinguished in colon cancer (OR = 1.35, 95% CI: 1.04-1.75) and Caucasian (OR = 1.32, 95% CI: 1.12-1.56). Our meta-analysis provides comprehensive support for a role of circulation IGF-I and IGF-II in the etiology of CRC.