The Cdx-2 polymorphism in the VDR gene is associated with increased risk of cancer: a meta-analysis

The Cdx-2 polymorphism in VDR gene has been extensively investigated for association with cancer risk, however, results of different studies have been inconsistent. The objective of this study is to assess the relationship of the Cdx-2 polymorphism in VDR and cancer risk by meta-analysis. All eligible case-control studies were searched in Pubmed, Embase, CNKI and Wanfang databases. Odds ratios (OR) with the 95 % confidence intervals (CI) were used to assess the association. A total of 12,906 cases and 13,700 controls in 18 case-control studies were included. The results indicated that the AA homozygote carriers had a 16 % increased risk of cancer, when compared with the homozygote GG and heterozygote AG (OR = 1.16, 95 % CI 1.05-1.29 for AA vs. GG+AG). In the subgroup analysis by ethnicity, significant elevated risks were associated with AA homozygote carriers in Caucasians (OR = 1.16, 95 % CI 1.01-1.33, and P = 0.04) and African Americans (OR = 1.31, 95 % CI 1.07-1.61, and P = 0.01). In the subgroup analysis by cancer types, the polymorphism was associated with increased risk of breast cancer (OR = 1.23, 95 % CI 1.04-1.46, and P = 0.02). This meta-analysis suggested that the Cdx-2 polymorphism of VDR gene would be a risk factor for cancer. To further evaluate gene-to-gene and gene-to-environmental interactions between polymorphisms of VDR gene and cancer risk, more studies with large groups of patients are required.