The associations of single nucleotide polymorphism rs 2295080 in mTOR with cancer risk : an updated meta-analysis

Many studies have examined the association of the mTOR gene rs2295080 (T/G) polymorphism with cancer susceptibility, but the findings have been inconsistent. To evaluate the effect of the mTOR rs2295080 polymorphism on cancer risk, fifteen articles (containing 9207 cases and 10739 controls) were examined for this metaanalysis. To assess the degree of association, odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using the random effects model. In total, our results indicated that rs2295080 is associated with a decreased risk of cancer in the dominant-model and in the heterozygous-model (TG + GG versus TT: OR = 0.88, 95% CI 0.79-0.99 P = 0.035; TG versus TT: OR = 0.89, 95% CI 0.81-0.98 P = 0.021). Performing a sub-group analysis based on systemic cancer type, we observed that the rs2295080 polymorphism decreased the cancer risk in urogenital system cancers (TG + GG versus TT: OR = 0.72, 95% CI 0.58-0.90 P = 0.004; G versus T: OR = 0.75, 95% CI 0.58-0.97 P = 0.026; TG versus TT: OR = 0.77, 95% CI 0.69-0.86 P = 0.000). It is noteworthy that we found the rs2295080 polymorphism significantly increased the risk in blood system cancers (GG versus TG + TT: OR = 2.25, 95% CI 1.30-3.91 P = 0.004; G versus T: OR = 1.24, 95% CI 1.05-1.47 P = 0.013; GG versus TT: OR = 2.25, 95% CI 1.33-3.82 P = 0.003). However, we did not find a correlation between the rs2295080 polymorphism and cancer risk of the digestive system in any of the five models. Thus, possible additional factors related to the risk of cancer of the digestive system should be investigated in further studies.