Relationship between CTLA-4 +49A>G polymorphism and the risk of lung adenocarcinoma in a Chinese Han population

Background: Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) is a transmembrane protein on the activated T-cell surface. It can inhibit T-cell proliferation and activation and it increases tumor susceptibility. Some reports have associated CTLA-4 +49A>G polymorphism with certain cancers, but the associations with lung cancer have been inconsistent. Therefore, we aimed to investigate the associations between CTLA-4 +49A>G polymorphism and the risk of lung cancer, as well as the risks of different pathological types of lung cancer. Methods: A total of 549 lung cancer patients and 611 healthy controls were included in this study. Taqman real-time polymerase chain reaction was used to analyze CTLA-4 polymorphisms. The chi-squared test was used to examine the differences between lung cancer patients and controls. The odds ratio (OR) and its 95% confidence interval (95% CI) were obtained by multivariate conditional logistic regression. Results: When the AA genotype was used as the reference group, the GG genotype was associated with an increased risk of lung cancer (OR = 1.697, 95% CI = 1.095-2.630, P = 0.018). Moreover, in the analysis of CTLA-4 +49A>G polymorphism and the risks of different pathological types of lung cancer, the GG genotype was associated with an increased risk of lung adenocarcinoma (OR = 2.443, 95% CI = 1.337-4.465; P = 0.004). Under the dominant model of inheritance, the AG+GG genotype was significantly associated with an increased risk of lung adenocarcinoma (OR = 2.095, 95% CI = 1.173-3.741; P = 0.012). Conclusion: The CTLA-4 +49A>G gene polymorphism is associated with a risk of lung adenocarcinoma in a Chinese Han population.