Stomach cancer in 67 Chinese counties: evidence of interaction between salt consumption and helicobacter pylori infection.

OBJECTIVE To examine the interaction between salt-intake and helicobacter pylori (H. pylori) infection in the development of stomach cancer in an ecological study of 67 Chinese rural counties. METHODS Stomach cancer mortality data of 67 counties were derived from a national survey conducted in China between 1986 and 1988. Information regarding the prevalence of H. pylori infection and urinary sodium excretion were collected from the same individuals during a subsequent dietary survey in 1989. RESULTS In these 67 counties, H. pylori prevalence and urinary sodium were correlated with stomach cancer mortality, with r=0.31 (p=0.01) and r=0.28 (p=0.03), respectively. After stratification, the significant correlation between H. pylori prevalence and stomach cancer mortality only existed in counties with high levels (> or =5.0 mg/mg creatinine/12-hour) of urinary sodium (r=0.5; p=0.002). Similarly, the significant correlation between urinary sodium and stomach cancer mortality was only presented in counties with high (> or =71.6%) H. pylori prevalence (r=0.4; p=0.017). Multivariate regression analysis showed results consistent with the correlation analysis. CONCLUSION These findings suggest that there may be an interaction between high salt consumption and H .pylori infection in the development of stomach cancer. Corroborating data from epidemiological, clinical, and experimental studies are needed.