Helicobacter pylori (HP) is the causative agent of gastric cancer, and the cancer-preventive effect of HP eradication has been in the limelight in recent years. Professor Take et al. from Fukutabi City Hospital in Japan reported their team’s latest findings in JGastroenterol. The team has done previous studies and found that HP eradication treatment in peptic ulcer patients reduced the risk of gastric cancer by about 1/3 (with an average follow-up period of 3.4 years). The current study still looked at the same cohort, but with a longer follow-up period (9.9 years on average). The 1222 peptic ulcer patients had annual endoscopic surveillance after HP eradication. Exclusion criteria included previous major gastrectomy; previous endoscopic EMR or ESD for early gastric cancer or adenoma; pregnant women; drug allergy; taking anticoagulants; and having taken PPIs, H2 receptor antagonists, and NSAIDs within 1 month of eradication therapy. The method of eradication therapy is: PPI + amoxicillin or PPI + any two of the following drugs (amoxicillin, clarithromycin, metronidazole). The criteria for successful eradication therapy were: negative bacterial culture, rapid urease test and breath test. As a result, 1030 patients were found to have successful eradication therapy (eradication success group) and 192 failed (eradication failure group). The failed eradication group was followed up for about 4.4 years and 105 patients were treated successfully. Gastric cancer occurred in 21 cases (0.21%/year) in the successful eradication group and in 9 cases (0.45%/year) in the failed eradication group. The risk of cancer in the former group was significantly lower than that in the latter group. The longest interval (completion of eradication therapy to gastric cancer onset) was 14.5 years in the successful eradication group and 13.7 years in the failed eradication group. This study confirms that the gastric cancer prevention effect of HP eradication therapy can be maintained for at least 10 years. For ulcer patients, young age and mild gastric mucosal atrophy were important influencing factors for the preventive effect; the longer HP was present in the gastric mucosa, the more extensive and severe the gastric mucosal atrophy. The team recommends early eradication of HP before gastric mucosa atrophy for the most effective cancer prevention. Another reason to eradicate HP early is that it reduces the number of infected hosts, because mother-to-child transmission of HP is most common in Japan, and eradicating HP before women have children can accelerate the decline in infection rates in the population. However, the researchers also found that HP eradication did not completely prevent the development of gastric cancer, and some patients still developed gastric cancer 10 years after HP eradication. Therefore, more in-depth studies are still needed in the future to clarify how to follow up patients who have been HP eradicated and how to detect gastric cancer in the early stage.