Helicobacter pylori infection is considered as the major etiologic factor for gastric cancer development. WHO-IARC declared the organism as a group I carcinogen for gastric cancer. However， recently published guidelines for North America suggested that there is no evidence to screen asymptomatic person， and Maastricht European consensus report suggested that the statement that H. pylori eradication can reduce gastric cancer development has low level of evidence. 

 

Meta-analysis which mainly included retrospective studies showed a definite reduction of metachronous gastric cancer development after H. pylori eradication in EGC patients treated with endoscopic resection. However， only two open-labeled randomized studies of short-term median follow up duration about 3 years or less have been performed in EGC patients until now. Moreover， those two studies showed conflicting results on the preventive effect of H. pylori treatment. Furthermore retrospective studies also reported conflicting results and a study showed that apparent gastric cancer incidence decrease within 5 years of follow-up finally abolished if follow-up duration extended to more than 5 years.

 

In our prospective double-blind randomized placebo-controlled trial， 396 patients who underwent endoscopic resection were randomly assigned to receive either H. pylori eradication therapy (treatment group， n=194) or placebo (placebo group， n=202) from August 2003 to March 2013. The?metachronous gastric cancer had developed in 27 patients in the placebo group (5-year cumulative incidence， 12.4%) and in 14 patients in the treatment group (5-year cumulative incidence， 5.5%) during a median follow-up of 5.8 years (P=0.0294). In the histological analysis， 327 patients were included who underwent 3-year follow-up biopsy. The proportion of patients showing improvement at atrophy grade was higher in the treatment group (48.4%) than that of patients in the?placebo group (15.0%; P<0.001). Our study suggested that even in gastric cancer patients who had already developed severe histological changes， H. pylori treatment could reduce metachronous gastric cancer development and improve corpus gastric atrophy.