Associations of tumor necrosis factor-α polymorphisms with the risk of colorectal cancer: a meta-analysis

Background: Recently, the roles of tumor necrosis factor-alpha (TNF-alpha) polymorphisms in colorectal cancer (CRC) were analyzed by some pilot studies, with inconsistent results. Therefore, we performed the present study to better assess the relationship between TNF-alpha polymorphisms and the risk of CRC. Methods: Eligible studies were searched in PubMed, Medline, Embase and CNKI. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess correlations between TNF-alpha polymorphisms and CRC. Results: A total of 22 studies were included for analyses. A significant association with the risk of CRC was detected for TNF-alpha -308 G/A (recessive model: P = 0.004, OR = 1.42, 95%CI 1.12-1.79) polymorphism in overall analyses. Further subgroup analyses based on ethnicity of participants revealed that TNF-alpha -238 G/A was significantly correlated with the risk of CRC in Caucasians (dominant model: P = 0.01, OR = 0.47, 95%CI 0.26-0.86; overdominant model: P = 0.01, OR = 2.27, 95%CI 1.20-4.30; allele model: P = 0.02, OR = 0.51, 95%CI 0.29-0.90), while -308 G/A polymorphism was significantly correlated with the risk of CRC in Asians (recessive model: P = 0.001, OR = 2.23, 95%CI 1.38-3.63). Conclusions: Our findings indicated that TNF-alpha -238 G/A polymorphism may serve as a potential biological marker for CRC in Caucasians, and TNF-alpha -308 G/A polymorphism may serve as a potential biological marker for CRC in Asians.