Lack of association between interferon gamma +874 T/A polymorphism and cancer risk: an updated meta-analysis

Interferon gamma (IFN-γ) is a potent proinflammatory cytokine which plays a pivotal role in the antiviral, antiproliferative, and antitumor activities. A T-to-A transition at the position +874 of human IFN-γ gene (IFNG) has been reported to influence the secretion of IFN-γ and affect cancer susceptibility. However, results from published studies on the association between IFNG +874 T/A polymorphism and cancer risk are inconclusive or even controversial. In order to derive a more precise estimation of the association, a meta-analysis of 38 eligible studies including 5,630 cases and 6,096 controls was conducted with odds ratio (OR) and its corresponding 95 % confidence interval (95 % CI). Overall, no significant association was detected in allelic model (A allele vs. T allele-OR = 0.96, 95 % CI, 0.86-1.08), homozygote comparison (AA vs. TT-OR = 0.97, 95 % CI, 0.79-1.21), heterozygote comparison (AT vs. TT-OR = 1.03, 95 % CI, 0.87-1.23), dominant model (AA + AT vs. TT-OR = 1.00, 95 % CI, 0.87-1.15), nor recessive model (AA vs. AT + TT-OR = 0.93, 95 % CI, 0.78-1.12). Further subgroup analyses based on ethnicity, cancer types, and Hardy-Weinberg equilibrium status failed to demonstrate any significant relationship except in African population under recessive model (AA vs. AT + TT-OR = 0.68, 95 % CI, 0.47-0.97). In conclusion, the current meta-analysis suggested that IFNG +874 T/A polymorphism may not contribute to cancer susceptibility, and further well-designed studies with large sample size are warranted to validate our conclusion.