Gastric cancer is the one of the most common cancers in Korea. From a global perspective, gastric cancer ranks third in cancer-related mortality [1]. Helicobacter pylori was classified as a Group 1 carcinogen for gastric cancer by the International Agency for Research on Cancer [2]. Therefore, there have been many studies on stomach cancer reduction after H. pylori eradication, particularly as to whether H. pylori eradication treatment could have a significant effect on the group at high risk for stomach cancer. Patients with early gastric cancer who received H. pylori treatment had lower rates of metachronous gastric cancer [3]. A recent meta-analysis of randomized controlled trials conducted in asymptomatic general populations reported a 34% reduction in the incidence of gastric cancer after H. pylori eradication [4]. Overall, we believe that eradication of H. pylori can lower the incidence of gastric cancer and may also reduce all-cause mortality. However, interestingly, one meta-analysis also demonstrated a non-significant increased risk in overall mortality with H. pylori treatment (risk ratio, 1.09; 95% confidence interval [CI], 0.86 to 1.38) [5]. In addition, another study demonstrated a reduced risk of gastric cancer but, again, showed a nonsignificant increased risk of all-cause mortality among patients randomized to eradication therapy compared to patients in a control group (hazard ratio, 1.95; 95% CI, 0.72 to 5.27; p = 0.19) [3]. These data suggest a potential harmful effect of H. pylori treatment in terms of increased non-gastric cancer mortality. This is a concern for a doctor prescribing eradication medicine and may damage the legitimacy of H. pylori eradication. However, the possible underlying mechanisms remain unclear, and this is not established theory. In Korea, gastric cancer was the most commonly diagnosed cancer in 2015, and the estimated prevalence of H. pylori infection was approximately 54% [6]. Therefore, unlike some other countries, this issue is of great significance in Korea.