This study was to confirm the relationship between RASSF1A methylation and gastric cancer, and effects of gender, age, stage, differentiation, pathological type and metastasis of gastric cancer on RASSF1A methylation.

Material and methods:
The database was searched for case-control studies of RASSF1A gene methylation associated with gastric cancer, and suitable literature was selected according to pre-defined inclusion and exclusion criteria. The quality of the included literature was evaluated, and finally forest plots and funnel plots were performed to analyse sensitivity and publication bias.

Finally, 13 papers met the requirements and were included in this study. Meta-analysis showed that RASSF1A gene methylation was associated with gastric cancer (effect size[ES]=17.13,95% confidence interval[CI]= 6.94-27.32,P=0.001; P for heterogeneity=0.183, I2=25.8% ). Age (OR=0.67, 95% CI 0.47-0.95,P=0.025; P for heterogeneity=0.257, I2=22.5%), gastric cancer stage (OR=0.62, 95% CI 0.44-0.88,P=0.008; P for heterogeneity=0.615, I2=0%) and gastric cancer metastasis (OR=2.60, 95% CI 1.04-6.46,P=0.040; P for heterogeneity=0.904, I2=0%) had an effect on RASSF1A gene methylation. Gender (OR=1.16, 95% CI 0.84-1.62,P=0.369; P for heterogeneity=0.704, I2=0%),degree of gastric cancer differentiation (OR=0.96, 95% CI 0.60-1.52,P=0.860; P for heterogeneity=0.077, I2=47.3%) and pathological type of gastric cancer (OR=1.15, 95% CI 0.64-2.09,P=0.635; P for heterogeneity=0.276, I2=22.5%) on RASSF1A gene methylation No effect. No significant publication bias was found in this study.

Gastric carcinogenesis is associated with RASSF1A gene methylation. Age, gastric cancer stage and gastric cancer metastasis affect RASSF1A gene methylation. Gender, degree of gastric cancer differentiation and type of gastric cancer pathology do not affect RASSF1A gene methylation, which may be an important direction for gastric cancer treatment.