Helicobacter pylori eradication prevents the development of gastric cancer - results of a long-term retrospective study in Japan

Effects of Helicobacter pylori eradication on gastric cancer incidence in the Japanese population: a systematic evidence review

BACKGROUND

In Japan, there are ongoing efforts to shift the gastric cancer prevention and control policy priorities from barium-based screening to Helicobacter pylori (H. pylori)-oriented primary prevention. A comprehensive summary of the evidence regarding the effects of H. pylori eradication on the risk of gastric cancer could inform policy decisions.

METHODS

We conducted a systematic review and meta-analysis of published studies evaluating the effectiveness of H. pylori eradication for the prevention of gastric cancer in otherwise healthy individuals (primary prevention) and early gastric cancer patients (tertiary prevention).

RESULTS

In total, 19 studies were included. Three moderate-quality observational cohort studies showed that H. pylori eradication may be associated with a decreased risk of gastric cancer in healthy asymptomatic Japanese people. There is moderate certainty regarding the effectiveness of H. pylori eradication in patients with gastrointestinal diseases, such as peptic ulcers. A meta-analysis of 10 observational studies with otherwise healthy individuals (mainly peptic ulcer patients) yielded an overall odds ratio of 0.34 (95% CI: 0.25-0.46). Regarding tertiary prevention, the overall odds ratio for developing metachronous gastric cancer was 0.42 (95% CI: 0.35-0.51) in the eradication group in a meta-analysis of nine studies involving early gastric cancer patients who underwent endoscopic resection.

CONCLUSION

H. pylori eradication is effective in preventing gastric cancer in the Japanese population, regardless of symptoms. Well-designed, large cohort studies are warranted to determine the long-term efficacy and safety of H. pylori eradication in the context of reducing the gastric cancer burden through population-based screening and treatment.

Characteristics of metachronous gastric tumors after endoscopic submucosal dissection for gastric intraepithelial neoplasms

Background. Recently, endoscopic submucosal dissection (ESD) has become a standard treatment method for early gastric cancer and concurrent stomach preservation. However, metachronous recurrences have become a major problem. We evaluated the incidence and clinicopathologic features of and examined the risk factors for metachronous gastric tumors. Methods. A total of 357 patients who underwent ESD for gastric tumors (245 early gastric cancers and 112 adenomas) and were followed up for more than 12 months without recurrence within the first 12 months were enrolled. We investigated the incidence and clinicopathologic features of metachronous tumors after ESD. We also analyzed the potential risk factors for metachronous tumors using the Kaplan-Meier method and Cox's proportional hazards model. Results. The annual incidence of metachronous tumors after ESD was 2.4%. The median period until discovery after initial ESD was 26.0 months, and the median observation period was 52.6 months. Male patients developed metachronous tumors more frequently (P = 0.04), and the hazard ratio of female to male patients was 0.36 (95% confidence interval: 0.11–0.89). Conclusions. Patients with a previous history of gastric tumors have a high risk of subsequent gastric tumor development and male patients should be carefully followed up after ESD for gastric tumor.

A study of metachronous cancer after endoscopic resection of early gastric cancer

OBJECTIVE

Endoscopic resection is commonly used for early gastric cancer (EGC) in Korea and Japan. There are only a few reports of metachronous cancer after endoscopic resection. The aim of this study was to identify clinical factors associated with metachronous gastric cancer after endoscopic resection.

METHODS

A total of 176 patients with EGC who had underwent endoscopic submucosal dissection (ESD) were periodically followed-up with endoscopic examinations from January 2004 to December 2007. The incidence and variable factors of metachronous gastric cancer were investigated in a retrospective study.

RESULTS

The median interval between the diagnosis of primary cancer and the diagnosis of the first metachronous cancer was 30 months (range 18-42 months). Metachronous gastric cancer had developed in nine patients (5.1%) during follow-up period and seven patients (4.0%) had synchronous gastric cancer lesions within 1 year of the initial endoscopic treatment. Annual incidence rate of metachronous cancer was approximately 3.3%. Antrum atrophy and old age were significantly associated with the incidence of metachronous cancer. The status of Helicobacter pylori, size, location and gross finding of lesion had no significant relationship with metachronous occurrence.

CONCLUSIONS

We should examine more carefully older patients who have atrophic gastritis because secondary cancer including metachronous cancer might occur in remnant stomach after initial successful endoscopic resection. And prospective study will be needed for the optimal endoscopic surveillance interval.

Gastric cancers in Finnish patients after cure of Helicobacter pylori infection: A cohort study

Helicobacter pylori infection is associated with gastric cancer. A total of 97% of the infected subjects have elevated levels of H. pylori antibodies. The antibody titers have been shown to decline rapidly (40-60% within 4-12 months) only after successful eradication therapy. We allocated 26,700 consecutive patients tested during 1986-1998 for H. pylori antibodies to 3 subcohorts: seropositive patients with rapidly falling antibody titers (Hp+CURED, n = 3,650), seropositive patients where no serological information indicating cure was obtained (Hp+NoInfo, n = 11,638) and seronegative patients (Hp-, n = 11,422). In the subcohorts, the standardised incidence ratios (SIRs) with 95% confidence intervals (CI) were defined for subsequent cancers of stomach, pancreas, colon, rectum, breast and prostate separately and for all cancers except stomach combined. The mean follow-up time was 10.1 years and the number of gastric cancers was 72. For the Hp+CURED, the SIR for gastric cancers for the first 5 follow-up years was 1.62 but decreased from the sixth follow-up year thereon to 0.14 (CI: 0.00-0.75). Likewise, the risk ratio, defined in a Poisson regression analysis using the Hp+NoInfo group as the reference, decreased from 1.60 to 0.13 (CI: 0.02-1.00, p = 0.049). The SIR for Hp- was not significantly higher than that for Hp+NoInfo for any of the cancers analysed. To conclude, cured H. pylori infection led to a significantly decreased incidence of gastric cancers from the sixth follow-up year. Advanced atrophic gastritis would be a plausible contributor to the elevated SIR in elderly Hp- patients.

Clinical prevention of gastric cancer by Helicobacter pylori eradication therapy: a systematic review

Helicobacter pylori (H. pylori) infection plays an important role in gastric carcinogenesis. We conducted a systematic review concerning gastric cancer development after H. pylori eradication therapy. In total 15 papers matched our criteria, the results were reviewed. The H. pylori eradication therapy statistically diminished the prevalence of clinical gastric cancer by approximately one-third. The studies from Japan supported this conclusion; however, studies from overseas reported conflicting results. The differences in these conclusions lie in the diagnostic ability of endoscopic examination, since the clinical stage was quite different between these studies. Gastric cancer that developed after eradication revealed a mainly intestinal type histology and depressed-type appearance. The following are possible reasons for reduced gastric cancer: (1) eradication therapy inhibits the new occurrence of gastric cancer, (2) eradication regresses or inhibits the growth of gastric cancer, and (3) eradication interferes with the discovery of gastric cancer. Considering the biological nature of cancer cell proliferation, a sufficiently long-term follow-up may clarify the effect of eradication therapy on inhibition of the development (not discovery) of gastric cancer and reduction of gastric cancer-related mortality.

Effect of eradication of Helicobacter pylori on incidence of metachronous gastric carcinoma after endoscopic resection of early gastric cancer: an open-label, randomised controlled trial

BACKGROUND

The relation between Helicobacter pylori infection and gastric cancer has been proven in epidemiological studies and animal experiments. Our aim was to investigate the prophylactic effect of H pylori eradication on the development of metachronous gastric carcinoma after endoscopic resection for early gastric cancer.

METHODS

In this multi-centre, open-label, randomised controlled trial, 544 patients with early gastric cancer, either newly diagnosed and planning to have endoscopic treatment or in post-resection follow-up after endoscopic treatment, were randomly assigned to receive an H pylori eradication regimen (n=272) or control (n=272). Randomisation was done by a computer-generated randomisation list and was stratified by whether the patient was newly diagnosed or post-resection. Patients in the eradication group received lansoprazole 30 mg twice daily, amoxicillin 750 mg twice daily, and clarithromycin 200 mg twice daily for a week; those in the control group received standard care, but no treatment for H pylori. Patients were examined endoscopically at 6, 12, 24, and 36 months after allocation. The primary endpoint was diagnosis of new carcinoma at another site in the stomach. Analyses were by intention to treat. This trial is registered with the UMIN Clinical Trials Registry, number UMIN000001169.

FINDINGS

At 3-year follow-up, metachronous gastric carcinoma had developed in nine patients in the eradication group and 24 in the control group. In the full intention-to-treat population, including all patients irrespective of length of follow-up (272 patients in each group), the odds ratio for metachronous gastric carcinoma was 0.353 (95% CI 0.161-0.775; p=0.009); in the modified intention-to-treat population, including patients with at least one post-randomisation assessment of tumour status and adjusting for loss to follow-up (255 patients in the eradication group, 250 in the control group), the hazard ratio for metachronous gastric carcinoma was 0.339 (95% CI 0.157-0.729; p=0.003). In the eradication group, 19 (7%) patients had diarrhoea and 32 (12%) had soft stools.

INTERPRETATION

Prophylactic eradication of H pylori after endoscopic resection of early gastric cancer should be used to prevent the development of metachronous gastric carcinoma.

FUNDING

Hiroshima Cancer Seminar Foundation.

Eradication of Helicobacter pylori for primary gastric cancer and secondary gastric cancer after endoscopic mucosal resection

Because most gastric cancers develop from a background of Helicobacter pylori-infected gastric mucosa, H. pylori plays an important role in gastric carcinogenesis. Therefore, eradication of H. pylori may inhibit the incidence of gastric cancers. In experimental studies, H. pylori eradication has proved to act as a prophylaxis against gastric cancer. However, the results of recent randomized controlled studies are absolutely contradictory. In Japan, mucosal gastric cancer is usually resected by endoscopic treatment. As only a small part of the gastric mucosa is resected, secondary gastric cancer after endoscopic resection of the primary gastric cancer often develops at another site in the stomach. A nonrandomized Japanese study involving 132 early gastric cancer patients reported that eradication of H. pylori after endoscopic resection tended to reduce the development of secondary gastric cancer. Also, a retrospective multicenter survey indicated that the incidence rate of secondary gastric cancer in H. pylori-eradicated patients was about one-third that among patients in the non eradication group. We conducted a large-scale multicenter randomized trial to confirm the effect of H. pylori eradication on secondary and residual gastric cancer after endoscopic resection. This study was begun in 2003 and is ongoing at present. Diagnosis of a new carcinoma at another site of the stomach is defined as the primary end point, and recurrence of tumors at the resection site as a secondary end point. A total of 542 subjects have been enrolled in the study. This study will have the statistical power to demonstrate whether H. pylori eradication decreases the incidence and recurrence of gastric cancer.