Inflammation is one of the early phases in the development of gastric cancer.
Several studies have examined the association of polymorphisms in tumor-necrosis factor-A gene with gastric cancer risk.
Dr Kamangar and colleagues from Maryland, USA conducted a meta-analysis of reviews and summarized published evidence for these associations.
|The overall odds ratios for TT genotypes for tumor-necrosis factor-A gene -857 was 1.6|
|British Journal of Cancer|
The team searched several databases yielding 24 independent studies that reported on the associations between tumor-necrosis factor-A gene polymorphisms and gastric cancer risk.
The team analyzed available data for the most commonly investigated polymorphisms.
The team noted that 23 studies investigated tumor-necrosis factor-A gene -308G>A, 9 studied tumor-necrosis factor-A gene -238G>A, and 5 studied tumor-necrosis factor-A gene -857C>T.
The team calculated summary odds ratios and 95% confidence intervals in the random-effects model using the DerSimonian-Laird method.
The researchers calculated q-statistic and used the I2-statistic to examine heterogeneity.
Funnel plots were plotted to examine small study effects.
The overall odds ratios for AG and AA genotypes vs GG genotype for tumor-necrosis factor-A gene -308 were 1.1, and 1.5, respectively.
The team found that for tumor-necrosis factor-A gene -238, the corresponding odds ratios were 1.05, and 1.3, respectively.
The overall odds ratios for CT and TT genotypes for tumor-necrosis factor-A gene -857 were 1.1, and 1.6, respectively.
The researchers found that the statistically significant association between tumor-necrosis factor-A gene -308GG and gastric cancer was limited to western populations.
This association showed little heterogeneity, and remained consistently strong when analyses were limited to anatomic and histologic subtypes of gastric cancer.
There was little heterogeneity when the analyses were limited to studies in which genotype frequencies were in Hardy-Weinberg equilibrium, or limited to larger studies.
The researchers observed that these same subgroup analyses did not change results associated with other polymorphisms.
Dr Kamangar's team concluded, "Tumor-necrosis factor-A gene -308AA genotype was associated with a statistically significant increased risk of gastric cancer, whereas other studied polymorphisms were not."
"The association between tumor-necrosis factor-A gene -857TT genotype, and gastric cancer was near significant, and may become significant if more studies are published."