Population-based cohort study of risk of gastric mucosa-associated lymphoid tissue lymphoma after Helicobacter pylori eradication treatment

Helicobacter pylori eradication leads to complete tumore regression in most gastric mucosa-associated lymphoid tissue (MALT) lymphomas. A population-based cohort study in Finland, Iceland, Norway, and Sweden investigated whether H. pylori eradication also reduces risk of developing gastric MALT lymphoma. During up to 18 years follow-up of 567,984 individuals (4,811,322 person-years) after H. pylori eradication, 23 gastric MALT lymphomas were identified. The risk of gastric MALT lymphoma was higher than that of the background population during the initial 1-5 years after eradication treatment (SIR 2.65; 95% CI 1.52-4.31) and became indistinguishable from that of the background population 6-18 years after treatment (SIR 0.96; 0.39-1.99). The pattern of lower risk estimates after 6-18 years than after 1-5 years was consistent across subgroups by sex, age, calender year, and autoimmune disease. The authors conclude that from six years after H. pylori eradication, the risk of gastric MALT lymphoma was no longer higher than that of the background population.