Helicobacter pylori Infection and Development of Gastric Cancer a 10-Year Follow-up Population-Based Study in a High Incidence Area

Backgrounds & Aim: H. pylori (HP) infection is the most important etiology of gastric cancer (GC) in the world but it causes GC in only a minority of those infected .Eradication of HP can decrease the development of GC only in the subgroup of HP infected subjects without precancerous lesions. Strategies of HP eradication is still not well defined in countries with high mortality rates secondary to GC with almost universal HP infection in adults. The aim of the present study was to investigate the predictors of GC in an adult population with almost universal HP infection in an area with highest rate of gastric cancer in the world. Methods: 1011 healthy subjects 40 years and older, permanent residents of Ardabil and Meshkinshahr districts in northwest Iran, were randomly selected and enrolled in an endoscopic screening study during 2000 to 2001 year. Data on demographics and potential risk factors were collected using a well-structured questionnaire. Upper gastrointestinal endoscopy with multiple biopsy sampling was performed to detect HP infection and endoscopic precancerous lesions.Participants have been followed up until 2011. During followup period data on the occurrence of GC, mortality, and cause of death were obtained from cancer and death registries, and when neccessary by direct contacting to participants, and their families. The cumulative incidence and person-time incidence rate were calculated. The effect of other risk factors in addition to H. pylori infection on the risk of GC development were estimated by fitting multivariate hazard model using Cox proportional regression analysis, and were presented as hazard ratio (HR) and corresponding 96% confidence interval (95%CI). Results: During 10-year follow up, 36 participants (3.6%) developed GC yielding an incidence rate of 3.6 per 1000 person-years. The significant risk factors of GC included age over 50 (HR 4.8; 95%CI 1.4-16.2), a positive family history of stomach cancer (6.4; 3.1-13.1), smoking (5.7; 2.5-12.6), gastric atrophy (2.3; 1.0-5.1), intestinal metaplasia (4.5; 2.3-8.9) and presence of gastric ulcer (4.8; 1.9-11.5). Joint presence of precancerous lesion and one of the other risk factors significantly increased risk of stomach cancer as (46.5; 10.8-98.6) for a positive family history of stomach cancer; (27.6; 6.5-116.4) for smoking and (25.1; 16.3-105.3) for age>50. Conclusion: Combining the information on family history, lifestyle risk factors and the type of precancerous lesion may be helpful in order to identify high risk HP infected patients who need more intensive surveillance for early detection of GC. Key words: Stomach cancer, Precancerous lesions, Risk factors, H. pylori, Ardabil,Iran.