Treating gastric bacteria may be linked to lower risk of developing stomach cancer

Findings offer important clues for gastric cancer prevention, say researchers

Treating the common stomach bacteria Helicobacter pylori with antibiotics for two weeks and taking vitamin or garlic supplements for just over seven years may be linked to a lower risk of developing stomach cancer in those at high risk, finds a study from China published by The BMJ today.

The results offer important clues for the prevention of gastric cancer in high risk populations, say the researchers.

H pylori is a bacteria that infects the lining of the stomach. It can be treated with antibiotics and normally won’t cause any major problems, but it can be associated with the development of stomach (gastric) cancer.

Eradicating H pylori could therefore be a potential strategy for preventing gastric cancer, but the long term effects of treatment need to be studied.

In 1995, the Shandong Intervention Trial set out to assess the effects of three interventions on gastric cancer in people from Linqu County, a rural area in northeastern China that has one of the highest gastric cancer death rates in the world. 

Evidence suggests that diets rich in vitamins and garlic could help protect against gastric cancer in high risk people, so the trial tracked the health of 3,365 adults with and without H pylori who were randomly given antibiotics for two weeks, vitamin or garlic supplements for just over seven years, or their placebos.

In 2010, after almost 15 years of follow-up, the trial reported that compared with placebo, antibiotic treatment was associated with a statistically significant reduction in new cases of gastric cancer, but no significant reduction in gastric cancer deaths.

Both garlic and vitamin supplements showed a non-statistically significant reduction in gastric cancer cases and deaths.

So, although the trial suggested a potential role of H pylori treatment in the prevention of gastric cancer, further follow-up was needed to determine whether the reductions would persist and lead to a noticeable decrease in gastric cancer mortality. 

It also remained unknown whether vitamin and garlic supplementation would be associated with statistically significant reductions in gastric cancer incidence and mortality in the longer term.

So researchers based in China and the US extended follow-up to 2017 (22 years after the trial began) and found a continued protective effect of antibiotic treatment on new gastric cancer cases. Cases also decreased significantly with vitamin supplements but not with garlic supplements. 

After adjusting for potentially influential factors, all three interventions showed significant relative reductions in gastric cancer mortality. 

No statistically significant associations were found between interventions and other cancers, such as bowel and liver cancer, or cardiovascular disease.

The researchers cannot rule out the possibility that some of the observed risk may be due to other unmeasured factors, and warn that applying their findings to a well-nourished population or a population with low levels of gastric cancer should be approached with caution.

Nevertheless, they say these findings “offer potential opportunities for gastric cancer prevention, but further large scale intervention trials are required to confirm the favorable effects of vitamin and garlic supplementation and to identify any possible risks of H pylori treatment, and vitamin and garlic supplementation.”

11/09/2019

Notes to Editors

Research: Effect of Helicobacter pylori treatment or vitamin or garlic supplementation on gastric cancer incidence and mortality: follow-up of a randomized intervention trial
Journal: The BMJ

Link to Academy of Medical Sciences press release labelling system: https://press.psprings.co.uk/AMSlabels.pdf

Peer-reviewed? Yes
Evidence type: Extended follow-up of randomised intervention trial
Subjects: People

Link to research: https://www.bmj.com/content/366/bmj.l5016