Effect of age on the relationship between gastric cancer and Helicobacter pylori

Helicobacter pylori is thought to be involved in the pathogenesis of gastri c cancer, but the time point at which it produces its effects (critical tim e) is unknown. We measured the serum level of H. pylori antibody in 787 gas tric cancer patients and 1007 controls aged 20 to 69, Odds ratios for diffe rent gastric cancer types and stages were determined for each 10-year age c lass, The overall odds ratio for gastric cancer decreased with age, being 7 .0 for those aged 20-29, 14.5 for those aged 30-39, 9.1 for those aged 40-4 9, 3.5 for those aged 50-59, and 1.5 for those aged 60-69 (trend in odds ra tios: P<0.01). However, there was no such age-dependent trend for early dif fuse-type cancer; the odds ratios were 12.6, 4.0, 7.2, 6.5, and 18.5 respec tively (P=0.29), Early cancer tended to show higher seroprevalence than adv anced cancer, especially in older subjects. No significant difference in se roprevalence was observed between diffuse and intestinal cancers within eac h age-class, Seroreversion must have occurred in the time interval between the critical time and the diagnosis of the cancer, especially in older pati ents. The age-dependent relationship between H pylori and gastric cancer ma y be due to seroreversion, which itself may be independent of age. This age -independence indicates that prolonged exposure to H. pylori does not incre ase the magnitude of its influence on gastric carcinogenesis. Possible mech anisms through which H. pylori exerts pathogenic effects are continuous inf lammation in adulthood and/or irreversible damage to gastric mucosa in chil dhood or the teenage years.