Prediagnosis lifestyle exposures and survival of patients with gastric cancer: systematic review and meta-analysis.

The relation between lifestyles and gastric cancer has been investigated thoroughly; however few studies have addressed the impact of these exposures on prognosis. Therefore, we quantified the association between prediagnosis smoking, alcohol intake and other dietary exposures and the survival of gastric cancer patients through a systematic review and meta-analysis. We searched Pubmed and EMBASE up to April 2011 and computed summary hazard ratio estimates and respective 95% confidence intervals (95% CIs) through a random-effects meta-analysis (DerSimonian and Laird). Heterogeneity was quantified using the I2 statistic. Seven articles, providing data from 6856 cases evaluated in seven countries (Canada, Japan, Italy, USA, Korea, Iran and Sweden), were eligible for meta-analysis. The summary hazard ratio was 1.08 (95% CI: 0.90-1.30) for smoking (current vs. never smokers, seven studies; I2=56.2%) and 1.13 (95% CI: 1.00-1.28) for alcohol consumption (drinkers vs. nondrinkers, five studies; I2=13.2%). Only two studies assessed the effect of other dietary factors. This study summarizes the best evidence available on the relation between prediagnosis lifestyles and the survival of gastric cancer patients. Alcohol drinkers have lower survival, but results on the effect of smoking lack consistency and there is almost no information on the effects of dietary factors.