Association between insulin-like growth factor 1 gene rs35767 polymorphisms and cancer risk: A meta-analysis.

Background: Several studies have been conducted on the relationship between insulin-like growth factor 1 gene (IGF-1) rs35767 polymorphisms and cancer risk, but the results are conflicting. We performed a meta-analysis to investigate the relationship between IGF-1 rs35767 polymorphisms and cancer risk. Methods: Eight studies (5 for IGF-1 rs35767 C>T and 3 for IGF-1 rs35767 A>G) with a total of 11,257 cases and 16,213 controls were included. The studies were about the association between IGF-1 rs35767 polymorphisms and cancer risk and acquired by searching PubMed, Embase, and Web of Science databases for articles published before January 20, 2019. STATA software was used to analyze the data and identify the strength of the association by using pooled-odds ratios (ORs) with corresponding 95% confidence intervals (CIs). Results: No significant associations were observed between the IGF-1 rs35767 C>T polymorphism and cancer risk in all genetic models. However, the IGF-1 rs35767 A>G polymorphism was significantly associated with increased cancer risk for all genetic models (G vs A: OR=1.087, 95% CI: 1.036-1.141, Ph=.338; GG vs AA: OR=1.272, 95% CI: 1.121-1.442, Ph=.359; AG vs AA: OR=1.187, 95% CI: 1.043-1.351, Ph=.695; AG+GG vs AA: OR=1.187, 95% CI: 1.043-1.351, Ph=.695; GG vs AA+AG: OR=1.086, 95% CI: 1.025-1.151, Ph=.275). Begg and Egger tests showed that no publication bias existed. Conclusion: Our findings indicated that the IGF-1 rs35767 A>G polymorphism might be a risk factor for cancer development. However, additional well-designed studies with sample sizes larger than ours need to be conducted in the future to verify our findings.