Helicobacter pylori infection and gastric cancer: evidence from a retrospective cohort study and nested case-control study in China.

Aim: To explore the association between Helicobacter pylori (Hp) infection and risk of gastric cancer in China.

Methods: Utilizing gastroendoscopic biospsy tissue banks accumulated from 1980 to 1988 in Shandong, Zhejiang, and Jiangsu, where stomach cancer incidence was high, during stomach cancer screening conducted by Health Science Center of Peking University, School of Medicine of Zhejiang University, and Zhongshan Hospital of Fudan University. Warthin Starry silver staining method was applied to determine H. pylori infection status of biopsies collected during gastroendoscopic examination. In the retrospective study, the subjects were divided into two cohorts, the exposure cohort was positive H. pylori infection, and the non-exposure cohort was negative. Death from stomach cancer was determined as the outcome of the study. Logistic regression and Cox regression were applied to analyze the association between Helicobacter pylori infection and gastric cancer risk. In the nested case-control study, there were 28 deaths from gastric cancer in the fields of Muping, Shandong province, and Zhoushan, Zhejiang provinces. 4 controls were matched to each case on the basis of age (+/-5 years old), sex, residential place at the same time entered into the study. Conditional logistic regression analysis was used to analyze the data.

Results: There were a total of 2 719 subjects (male 1 399, female 1 320) with gastroendoscopic biopsies stored available treated as a cohort. H. pylori positive cohort included 1 671 subjects (61.5 %) and H. pylori negative cohort 1 048 subjects(38.5 %). These subjects were followed up for 1-19 years, averaged 10.88 years. The outcome of death from stomach cancer in the exposure cohort was 33, and in the non-exposure cohort 11. After adjustment for age and sex, RR=1.9850 (P=0.0491), 95 % CI was 1.0026, and 3.9301. The results of conditional logistic regression showed an OR of 4.467 and 95 % CI of 1.161, and 17.190 for the nested case control study.

Conclusion: The results from the retrospective cohort study and the nested-case control study on the association of H. pylori infection and gastric cancer in China suggested that Helicobacter pylori infection might increase the risk of stomach cancer.