Targeting bacteria causing ulcers may prevent stomach cancer

Stomach, or gastric, cancer is the third most common cause of death from cancer worldwide, and people who are infected with the Helicobacter pylori bacterium are more likely to develop the disease.

About two-thirds of the population has H. pylori in their bodies, but in most cases people experience no discomfort or other symptoms. However, it can be eradicated with a simple short course of antibiotics, often used with another medicine that suppresses the production of gastric acid.

"The findings of this systematic review add to the increasing evidence that eradicating H. pylori in the general population has the potential to prevent gastric cancer," said co-author Dr. Paul Moayyedi. He is a professor of medicine of the Michael G. DeGroote School of Medicine at McMaster University, a scientist of the Farncombe Family Digestive Health Research Institute and a gastroenterologist at Hamilton Health Sciences.

"International guidelines for the management of H. pylori infection may change as a result," he added.

To determine whether eliminating H. pylori might reduce the incidence of gastric cancer, the researchers analysed all published randomized controlled trials which compared at least one week of H. pylori therapy with placebo or no treatment, in otherwise healthy and asymptomatic H. pylori-positive adults. The review included only trials that followed participants for at least two years and that had at least two participants who developed gastric cancer.

Six trials with a total of nearly 6,500 participants met the researchers' criteria. The studies mainly used a combination of antibiotics with medicines from a class of drugs that suppress gastric acid production (called proton pump inhibitors). An analysis of the studies' results revealed that combining antibiotics with gastric acid suppressor therapy given for between one and two weeks prevented the development of gastric cancer compared with placebo or no treatment.

In the studies, 51/3294 (1.6%) of the people given H. pylori treatment developed gastric cancer compared with 76/3203 (2.4%) given no treatment or a placebo. However, the number of deaths from gastric cancer in the trials was low, and there was insufficient evidence to determine how much of a difference eradicating H. pylori made to survival.

Moayyedi added: "We feel our review provides sufficient evidence for countries with high gastric cancer rates to consider population H. pylori testing and treating. More research is needed on the extent of this effect and on any potential harms of H. pylori treatment, so any country starting screening should do pilot projects to obtain more information on these issues."

Lead author Alex Ford, of St. James's University Hospital and Leeds University in the U.K., added: "The review highlights the need for further trials in different populations to provide more evidence, and these should report both the benefits and harms of such an approach."