Gastric cancers in finnish patients after cure of helicobacter pylori infection: a cohort study.

Helicobacter pylori infection is associated with gastric cancer. A total of 97% of the infected subjects have elevated levels of H. pylori antibodies. The antibody titers have been shown to decline rapidly (40-60% within 4-12 months) only after successful eradication therapy. We allocated 26,700 consecutive patients tested during 1986-1998 for H. pylori antibodies to three subcohorts: seropositive patients with rapidly falling antibody titers (Hp+CURED, n=3,650), seropositive patients where no serological information indicating cure was obtained (Hp+NoInfo, n=11,638) and seronegative patients (Hp-, n=11,422). In the subcohorts, the standardised incidence ratios (SIRs) with 95% confidence intervals (CI) were defined for subsequent cancers of stomach, pancreas, colon, rectum, breast and prostate separately and for all cancers except stomach combined. The mean follow-up time was 10.1 years and the number of gastric cancers 72. For the Hp+CURED, the SIR for gastric cancers for the first five follow-up years was 1.62 but decreased from the sixth follow-up year thereon to 0.14 (CI: 0.00-0.75). Likewise, the risk ratio (RR), defined in a Poisson regression analysis using the Hp+NoInfo group as the reference, decreased from 1.60 to 0.13 (CI: 0.02-1.00, p = 0.049). The SIR for Hp- was not significantly higher than that for Hp+NoInfo for any of the cancers analysed. To conclude, cured H. pylori infection led to a significantly decreased incidence of gastric cancers from the sixth follow-up year. Advanced atrophic gastritis would be a plausible contributor to the elevated SIR in elderly Hp- patients. (c) 2010 UICC.