Abstract
Background: Gastric cancer is globally the fifth most common cancer. Several studies have assessed the relationship between tumour necrosis factor-alpha (TNF-a- 308) and the risk of gastric cancer. These individual genetic association studies showed inconclusive results. The objective of the present study was to synthesis evidence on the association between TNF-a-308 polymorphisms and gastric cancer risk by meta-analysis of data from eligible studies.Methods: We performed a meta-analysis of genetic association studies, according to the PLOS One checklist. We searched relevant case-control studies in health-related electronic databases. The methodological quality of included studies was assessed by the Newcastle-Ottawa quality assessment scale. The strength of association was calculated as odds ratios (ORs) with 95% confidence intervals (CIs). Pooled ORs and 95 % CIs were estimated using random-effects model or fixed effect model, based on between-study heterogeneity. We analysed the strength of association under four genetic models (allele, dominant, recessive and additive models). Subgroup analyses on ethnic groups, Hardy-Weinberg equilibrium (HWE) status, status of Helicobacter pylori infection and study quality were done for robustness of the estimates. Publication bias was detected by inspection of funnel plot asymmetry. To estimate the required information size, we performed trial sequential analysis (TSA) that classified the effect estimates as ‘firm evidence of effect’ or ‘potentially spurious evidence of effect’.Results: A total of 35 studies, comprising 11353 cases and 12827 controls were identified. Based on 28 studies that met HWE, there was overall significant association between TNF-α-308 polymorphisms and gastric cancer risk under the dominant model (OR 1.19, 95%CI 1.1-1.29, I2:37%), as well as Asians (OR 1.2, 95%CI 1.05-1.38, I2:53%) and Cassian subgroups (OR 1.19, 95%CI 1.07-1.31, I2:28%). Based on 13 high quality studies under the dominant model, overall significant association was also found (OR 1.38, 95%CI 1.07, 1.77). The TSA plot indicated the analyses was with the required information size. There was no publication bias. In the subgroup analysis by ethnic groups, the quality of studies impacted on the estimates. Conclusions: The findings suggest that TNF-α-308 gene polymorphism plays an important predisposing role for gastric carcinogenesis, and can serve as a useful screening marker.
Comparative analysis of robotic gastrectomy and laparoscopic gastrectomy for gastric cancer in terms of their long-term oncological outcomes: a meta-analysis of 3410 gastric cancer patients
