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HELICOBACTER PYLORI ERADICATION REDUCES THE INCIDENCE OF GASTRIC CANCER: RESULTS OF A SYSTEMATIC REVIEW OF RANDOMIZED CONTROLLED TRIALS
P Moayyedi, RH Hunt, AC Ford, D Forman*
McMaster University, Hamilton; *University of Leeds, Leeds, UK
INTRODUCTION: Epidemiological data and animal models suggest H. pylori infection is an important cause of non-cardia gastric cancer. This is the second commonest cause of cancer mortality worldwide and is potentially preventable by population H. pylori screening and treatment. Randomized controlled trials (RCTs) have not shown that H. pylori eradication has reduced gastric cancer incidence. This could be because trials have been underpowered for this outcome so we conducted a systematic review of the literature.
METHODS: Electronic searches were performed using the Cochrane Controlled Trials Register, Medline, and EMBASE until September 2007. Abstracts were searched from DDW, UEGW and Asian Pacific Digestive Week until 2007. Further information was obtained from authors if necessary. RCTs comparing H. pylori eradication with no intervention or placebo in infected subjects followed up for at least two years with at least two gastric cancers during follow up were eligible for inclusion. Eligibility and data extraction was performed by two independent researchers. The primary outcome was relative risk (RR) of gastric cancer in the eradication arm compared to controls.
RESULTS: We identified 5 eligible trials evaluating 5676 subjects. Three studies were from China and two from Japan with an average of 2.4 to 12 years of follow up. Overall 130 gastric cancers were identified during follow up. There was no statistically significant heterogeneity between studies (Cochran Q = 1.62; degrees of freedom = 4, p=0.81, I2 = 0%) and random and fixed effects models gave similar results. Overall there was a reduced risk of developing gastric cancer in the H. pylori eradication arm (RR = 0.56; 95% CI = 0.4 to 0.8). In these high risk populations the number needed to treat was 227 (95% CI = 167 to 500). There was no funnel plot asymmetry and systematically removing one trial from the dataset did not alter the result.
CONCLUSIONS: This is the first study to demonstrate that H. pylori eradication can prevent gastric cancer in RCTs. This has important public health implications for the development of screening programs.