Short-term Helicobacter pylori treatment was associated with reductions in gastric cancer incidence and mortality over 22 years’ follow up, in research from China. The authors of the study*, published today in The BMJ, said these findings among others “suggest many potential strategies for gastric cancer prevention” – but they added that more large-scale intervention trials are needed before major public health campaigns for gastric cancer prevention are launched utilising antibiotic-based H. pylori treatment or nutritional regimens.
The researchers, led from the Peking University Cancer Hospital and Institute in Beijing, pointed out that previous epidemiological research has provided solid evidence linking H. pylori infection with the progression of precancerous gastric lesions and development of gastric cancer, and shown that diets rich in vitamin and garlic could protect against gastric cancer in high-risk people with insufficient vitamin intake. They conducted a blinded randomised placebo-controlled trial to assess the effects of H. pylori treatment, vitamin supplementation, and garlic supplementation in the prevention of gastric cancer.
Participants were 3,365 residents of a high-risk region for gastric cancer. Of these, 2,258 were seropositive for antibodies to H. pylori and were randomly assigned to H. pylori treatment (1g amoxicillin and 20mg omeprazole, twice daily for two weeks), vitamin supplementation (C, E, and selenium), garlic supplementation (extract and oil), or their placebos in a 2×2×2 factorial design, for 7.3 years, from 1995-2003. The 1,107 H. pylori seronegative participants were randomly assigned to vitamin supplementation, garlic supplementation, or their placebos in a 2×2 factorial design.
From 1995 to 2017 there were 151 incident cases of gastric cancer and 94 deaths from gastric cancer. The study authors reported that even 22 years after the intervention, a protective effect of H. pylori treatment on gastric cancer incidence persisted (hazard ratio, HR 0.48). A significant decrease in incidence was also associated with vitamin supplementation (HR 0.64), but not with garlic supplementation (HR 0.81).
In terms of gastric cancer mortality, all three interventions were significantly associated with a reduction in risk (fully adjusted HR for H. pylori treatment 0.62; for vitamin supplementation 0.48; and for garlic 0.66).
The study authors noted that the effects of H. pylori treatment on both gastric cancer incidence and mortality, and of vitamin supplementation on gastric cancer mortality, appeared early. The effects of vitamin supplementation on gastric cancer incidence and of garlic supplementation only appeared later.
They added that they found no statistically significant associations between any of the interventions and other cancers or cardiovascular disease.
They concluded: “Short-term H. pylori treatment was associated with a significantly decreased risk of gastric cancer incidence and mortality during 22.3 years of follow-up and was not significantly associated with total mortality or other major cancer-specific mortality. Both vitamin (C, E, and selenium) and garlic (extract and oil) supplementation for 7.3 years yielded statistically significant reductions in gastric cancer mortality, whereas a favourable effect of long-term vitamin supplementation on gastric cancer incidence was also observed.
“These findings offer potential opportunities for gastric cancer prevention, but further large-scale intervention trials are required to confirm the favourable effects of vitamin and garlic supplementation and to identify any possible risks of H. pylori treatment, and vitamin and garlic supplementation.”
*Li W-Q, Zhang J-Y, Ma J-L, et al. Effect of Helicobacter pylori treatment or vitamin or garlic supplementation on gastric cancer incidence and mortality: follow-up of a randomized intervention trial. BMJ 2019; 366: l5016 doi: 10.1136/bmj.l5016.