Based on a universal eradication of H. pylori in an offshore island (Matsu) with a high prevalence of gastric cancer as well as premalignant gastric lesion, we first examined the infection rate of H. pylori. Secondly, we evaluated the efficacy of clarithromycin-based triple therapy with a levofloxacin-based rescue treatment. And thirdly, we tested the hypothesis that whether the cure of H. pylori can reverse the premalignant gastric lesion. Fourth, we determine the cost-effectiveness of this intervention. The gene-environment interaction will be addressed regarding gastric cancer carcinogenesis. Finally, the incident rate of gastric cancer would be followed in this cohort.

Despite the decline of global incidence, gastric cancer still affects public health substantially due to the considerable medical burden in the treatment of disease at the symptomatic stage. This fact has prompted clinicians to extend their attention from the multidisciplinary therapies to the design of preventive strategies. Gastric cancer development follows a carcinogenic process from non-atrophic gastritis, atrophic gastritis, intestinal metaplasia, dysplasia, and eventually to the adenocarcinoma. Helicobacter pylori (H. pylori) infection triggers this carcinogenic cascade and its eradication is currently the most reliable regimen to arrest the histologic progression in order to prevent gastric cancer. Emerging data have suggested that the benefit of H. pylori treatment earlier in the course of infection is larger and cannot be outweighed by a disfavored discount rate as a result of different time horizons between early treatment and later benefit of averting advanced cancer.

In the Asia-Pacific area, however, virulent strains of H. pylori infection are highly prevalent and premalignant gastric lesions may have already developed at the take-off age of active intervention. Our current knowledge remains limited in answering whether H. pylori eradication can regress these premalignant lesions and if so, what determinant can contribute to a positive response is unknown. The concept of "a point of no return" suggests that the benefit of H. pylori eradication may diminish at later stages when many types of molecular damage become irreversible. Several population-based studies, in contrast, found that the premalignant gastric lesions were potentially reversible given a sufficiently long duration free from infection. The inconsistence may reflect the facts that studies with adequate sample size and long enough follow-up are rarely available and that some important factors, such as the variation in host susceptibility to disease and dietary exposure to carcinogens, are difficult to be measured but they are likely to confound the results.

Therefore, the present study was to:

1. Determine the efficacy of a novel regimen to treat the H. pylori infection in the general population.
2. To address the question whether the premalignant gastric lesion could be reversed following the cure of infection.
3. To simulate the cost-effectiveness of this chemoprevention.
4. To use individual data to empirically calculate the cost-effectiveness of this intervention.
5. To address the host genetic susceptibility to gastric cancer development.
6. To follow-up the gastric cancer incidence following the eradication of H. pylori.

Inclusion Criteria:

• Helicobacter pylori infection subjects

Exclusion Criteria:

• Prior gastrectomy; pregnant women