H. pylori and gastric cancer
Ford, 2015 Sugano, 2015 Malfertheiner, 2017
The prevalence of gastric cancer is falling in Australia in parallel with the decline in the prevalence of H. pylori. High-risk groups are those with a greater risk of H. pylori infection (especially migrants from high-prevalence regions [eg East Asia, Mediterranean])Rawla, 2019, older people and those with a family history of gastric cancer. H. pylori infection confers a lifetime risk of gastric cancer of up to 2%.
Evidence that treating H. pylori reduces the risk of gastric cancer is now sufficiently compelling that the Kyoto Global Consensus on H. pylori gastritis1 recommends population screening and treatment in communities where H. pylori infection is common and the prevalence of gastric cancer is considerable. This has relevance to high-risk groups in Australia (ie patients of Japanese, Korean or Chinese descent), even though Australia is not considered a high-prevalence country overall. In Australia, the decision to test for H. pylori should be individualised (see Overview of indications for H. pylori testing and eradication therapy).
Eradication therapy for H. pylori is strongly indicated in infected people with a close family history of gastric cancer, those with known intestinal metaplasia, and in any patient who has been treated for early gastric cancer. It may also benefit any infected person by reducing lifetime risk of cancer.
The risk of gastric cancer is increased when H. pylori-induced atrophy, intestinal metaplasia or dysplasia are present. Eradicating H. pylori before these changes have occurred reduces the risk of subsequently developing gastric cancer. When eradication has been achieved but intestinal metaplasia is already present and extensive, the risk of gastric cancer remains, though it may be reduced. In individual cases, surveillance of patients with intestinal metaplasia may be of benefit, but a reduction in mortality from surveillance has not been conclusively proven.
Gastric mucosa–associated lymphoid tissue (MALT) lymphoma is an uncommon disease, but most cases are caused by H. pylori infection. Eradicating H. pylori when the lymphoma is still at a low-grade stage usually results in regression and cure.