The genetic association between EGF A61G polymorphism (rs4444903) and risk of colorectal cancer An update meta-analysis and trial sequential analysis

Background: Colorectal cancer was a complex disease with multiple causative factors including genetic and environmental factors, as well as the interaction of the 2 factors. Relationship between epidermal growth factor (EGF) A61G polymorphism and colorectal cancer risk has been widely investigated previously, whereas results derived from these studies were inconclusive and controversial. The aim of this study was to investigate the association between the EGF A61G polymorphism and colorectal cancer using a meta-analysis of existing literature. Methods: Literature search was conducted from PubMed, EMBASE, China National Knowledge Infrastructure, Wanfang, and Cochrane library databases before July 2017. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the strength of the association between EGF A61G and colorectal cancer. Results: A total of 9 studies that involved 1448 cases and 1928 healthy controls and found allelic (OR=1.18, P=. 04) and recessive models (OR=1.36, P=. 03) of EGF A61G were significantly associated with the risk of colorectal cancer. Stratification analyses by ethnicity indicated that the EGF 61G significantly increased the risk of colorectal cancer in the Caucasian subgroup (OR=1.24, P=. 02), but not in Asian subgroup (OR=1.12, P=. 08). And the frequency of GG genotype of EGF A61G significantly increased in cases than that in healthy controls in both Caucasian (OR=1.40, P=. 04) and Asian subgroups (OR=1.27, P=. 01). Furthermore, the sample sources and genotyping methods seem to have no influence on the correction of EGF A61G and colorectal cancer susceptibility (P>. 05). Conclusion: The results indicate that EGF A61G might increase the risk of colorectal cancers.