In a recent issue of Gut, Marino et al showed that eradication of Helicobacter pylori resulted in increased levels of vitamin B‐12 (cobalamin) and decreased levels of plasma homocysteine in elderly patients (Gut 2007;56:469–74), confirming preliminary reports.1 The authors recall that cobalamin deficiency is associated with H pylori infection and is a major cause of hyperhomocysteinaemia in the general population.
Global DNA hypomethylation, which is associated with hyperhomocysteinaemia,2 is an epigenetic event often found in tumour cells.3 The homocysteine raising effect of H pylori may thus promote gastric carcinogenesis. Consistently, a recent study showed that hyperhomocysteinaemia may increase the risk of developing gastric cancer in a Chinese population.4 Along with Marino's results, these findings may provide new insights in our understanding of H pylori related gastric carcinogenesis.
One question remains open: Is eradication of H pylori the best way to prevent gastric cancer? The conclusion of the Maastricht III consensus report was that “Eradication of H pylori infection has the potential to reduce the risk of gastric cancer development”.5 Indeed, current evidence is insufficient to accurately identify a definitive population where prevention or treatment strategies have to be targeted. In this regard, future trials to identify high risk individuals for gastric cancer are eagerly awaited.6
Collectively, the above findings suggest that prevention strategies might target a subset of patients with lowest serum cobalamin levels. One question thus arises: Should we screen and treat H pylori positive patients for cobalamin deficiency (and hyperhomocysteinaemia) to reduce the risk of gastric cancer?
Future epidemiological and intervention studies assessing the influence of eradication of H pylori on the risk of gastric cancer must include the measurement of cobalamin and plasma homocysteine concentrations. This may shed new light on the H pylori story.7
Footnotes
Conflict of interest: None declared.
References
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