Yi-Chia Lee

In most Asian countries, cancer epidemiology has gradually shifted toward the Western pattern. However, gastric cancer remains a pressing issue because elderly populations are increasing and their exposure to risk factors has been continuous for decades; as a result, a constant level in the absolute number of new cases is observed. Reduction of gastric cancer mortality is our utmost goal while cancer mortality is the final product from the counterbalance of cancer incidence and survival. To reduce the burden from gastric cancer, a dual approach including cancer prevention and early detection is needed. Now, compelling evidences from randomized controlled trials and cohort studies have confirmed that eradication of Helicobacter pylori can reduce the incidence of gastric cancer. For high-risk populations, implementation of an organized mass eradication program with standardized protocols of diagnosis and treatment has been proven possible and effective. In addition, it is advisable to modify the life-style factors, such as eating more fruits and vegetables, using less salt, and avoiding smoking and excessive consumption of alcohol. The second approach involves endoscopic detection of gastric neoplasms so the cancer survival can be improved through removal of premalignant gastric lesions and early-stage gastric cancer.

In Taiwan, programmatic gastric cancer prevention was implemented between 1996 and 1998 in Matsu Island, with the first stage consisted of a standardized questionnaire and serum pepsinogen measurement and the second stage included endoscopic examination for subjects with a positive result, aiming to identify gastric cancer at the pre-symptomatic stage. In 2004, a mass eradication program for H. pylori was launched and aimed to prevent gastric cancer right at its starting point of carcinogenesis, which greatly expanded our view of gastritis and risk factors for gastric cancer. Up to now, there were six rounds of mass eradication programs in 2004, 2008, 2012, 2014, 2016, and 2018. The H. pylori infection has declined from 64% before program to around 10% in recent years. The effectiveness of reducing the incidence of peptic ulcer disease was 67.4%, the reduction of atrophic gastritis (a surrogate endpoint for gastric cancer) was significant at 77.2%, and using the gastric cancer incidence as the endpoint, a reduction of 51.3% was observed in 2015, twelve years after the implementation of this policy.

While in the setting of mass screening, irreversible damage may already have occurred after patients have harbored H. pylori infection for decades before they undergo screening and treatment for H. pylori. Therefore, a secondary prevention program with the first stage consisted of biomarker measurement was appended to the gastric cancer preventive programs since 2015. This serological approach has stratified the population, who was mostly free from H. pylori after a series of eradication programs, into different risk groups and those who were categorized as high risk would be invited to undergo endoscopic surveillance. Furthermore, with the advent of genomics, the evaluation of epigenetic markers in gastric mucosae was also explored so an individually-tailored preventive strategy that properly integrates the H. pylori eradication and targeted endoscopic screening has gradually been realized.

To summarize, in Matsu Islands, the gastric cancer prevention programs have made great contribution on our understanding of the role of H. pylori infection in gastric cancer prevention, the applicability of an organized preventive program, and the ability to properly allocate the limited endoscopic resources. These accomplishments have important implications for establishing a healthcare policy that can be applicable worldwide and can effectively eliminate the threat of gastric cancer. It is also noteworthy that an individually-tailored approach taking into account the multistep and multifactorial property of carcinogenesis has provided an opportunity of shared decision-making for personalized prevention for gastric cancer.