The association between UGT1A7 polymorphism and cancer risk: a meta-analysis

Background: studies investigating the associations between UDP-glucuronosyltransferase 1A7 (UGT1A7) gene polymorphisms and various carcinomas risk reported conflicting results. To derive a more precise estimation of the association, we have conducted a meta-analysis. Methods: data were collected from the following electronic databases: PubMed, Medline and Chinese Biomedical Literature Database, with the last report up to September 2011. Case–control studies containing available genotype frequencies of UGT1A7 were chose. The odds ratio (OR) and its 95% confidence interval (95%CI) were used to assess the strength of association. Results: a total of 22 separate case–control studies including 3852 cases and 5604 controls based on the search criteria were involved in this meta-analysis. The combined results based on all studies showed that there was a statistically significant link between UGT1A7*3 allele and cancer risk (OR = 1.31, 95%CI = 1.14–1.50, P = 0.0001). In the stratified analysis by racial descent, significant increased risk was found in Asian population for UGT1A7*3 allele (OR = 1.41, 95%CI = 1.22–1.63, P < 0.00001). No significant associations were found between the UGT1A7 polymorphism and cancer susceptibility among Caucasians and African-Americans. In the subgroup analysis by cancer types, significant associations were found in UGT1A7*2 allele (OR = 1.23, 95%CI = 1.06–1.43, P = 0.006) and *3 allele (OR = 1.51, 95%CI = 1.11–2.06, P = 0.009) for hepatocellular carcinoma, *3 allele for lung cancer (OR = 1.36, 95%CI = 1.11–1.68, P = 0.004) and for bladder cancer (OR = 1.50, 95%CI = 1.09–2.07, P = 0.01). Conclusions: This meta-analysis suggests that the UGT1A7*3 allele is a risk factor for cancer among Asians, especially for hepatocellular carcinoma.