The -765G>C polymorphism in the cyclooxygenase-2 gene and digestive system cancer: a meta-analysis.

BACKGROUND Published data regarding associations between the -765G>C polymorphism in cyclooxygenase-2 (COX-2) gene and digestive system cancer risk have been inconclusive. The aim of this study was to comprehensively evaluate the genetic risk of the -765G>C polymorphism in the COX-2 gene for digestive system cancer. MATERIALS AND METHODS A search was performed in Pubmed, Medline (Ovid), Embase, CNKI, Weipu, Wanfang and CBM databases, covering all studies until Feb 10, 2014. Statistical analysis was performed using Revman5.2. RESULTS A total of 10,814 cases and 16,174 controls in 38 case-control studies were included in this meta-analysis. The results indicated that C allele carriers (GC+CC) had a 20% increased risk of digestive system cancer when compared with the homozygote GG (odds ratio (OR)=1.20, 95% confidence interval (CI), 1.00-1.44 for GC+CC vs GG). In the subgroup analysis by ethnicity, significant elevated risks were associated with C allele carriers (GC+CC) in Asians (OR = 1.46, 95% CI=1.07-2.01, and p=0.02) and Africans (OR=2.12, 95% CI=1.57-2.87, and p< 0.00001), but not among Caucasians, Americans and mixed groups. For subgroup analysis by cancer type (GC+CC vs GG), significant associations were found between the -765G>C polymorphism and higher risk for gastric cancer (OR=1.64, 95% CI=1.03-2.61, and p=0.04), but not for colorectal cancer, oral cancer, esophageal cancer, and others. Regarding study design (GC+CC vs GG), no significant associations were found in then population-based case-control (PCC), hospital-based case-control (HCC) and family-based case-control (FCC) studies. CONCLUSIONS This meta-analysis suggested that the -765G>C polymorphism of the COX-2 gene is a potential risk factor for digestive system cancer in Asians and Africans and gastric cancer overall.