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.