WASHINGTON (Reuters) - People who have surgery to remove stomach cancer can cut the risk that it will return by getting antibiotics to eliminate a type of bacteria infecting the stomach’s lining, researchers said on Thursday.

The drugs targeted Helicobacter pylori, a corkscrew-shaped bacteria that is a leading cause of stomach ulcers and also is associated with stomach cancer and other ailments.

The study, published in the Lancet medical journal, found that getting rid of this bacteria reduced the risk of further stomach cancer by about two-thirds over three years.

The study, led by Dr. Mototsugu Kato and Dr. Masahiro Asaka of Hokkaido University in Japan, involved 544 people with early-stage stomach cancer, half who were given the drug treatment and half of who were not. All of them had undergone surgery to remove the tumor.

The drug-treated group got a week of twice-daily doses of the antibiotics amoxicillin and clarithromycin and the ulcer drug lansoprazole, sold by Japan’s Takeda Pharmaceutical Co Ltd as Prevacid.

“We believe that our data add to those from previous studies showing a causal relationship between H. pylori infection and gastric cancer, and also support the use of H. pylori eradication to prevent the development of gastric cancer,” the researchers wrote.

H. pylori can infect the mucous layer that coats the lining of the stomach. Long-term infection can lead to inflammation that can trigger precancerous changes in the stomach lining.

There are estimates that the bacteria infects half the world’s people, with the rate around 70 percent in developing countries and 20 to 30 percent in developed countries. Most who carry the bacteria have no symptoms of infection.

“No one’s been sure that if you intervene by getting rid of this bacteria at this late stage that it will do any good,” Dr. Nicholas Talley of the Mayo Clinic in Jacksonville, Florida, who wrote a commentary accompanying the study, said in a telephone interview.

The findings support the idea that getting rid of the bacteria could help prevent stomach cancer from developing, Talley said. But experts are still debating the issue.

Talley said it might be a good idea to screen people in high-risk places, including Japan and South Korea, for H. pylori infection, and give drugs to treat infected people.

This could involve millions of people getting blood or other tests for H. pylori infection, he said. “There’s a lot of people in the world who are older, who have this bacteria, who have some of these precancerous changes,” Talley added.

According to the American Cancer Society, stomach cancer is the No. 2 cause of cancer death in men and the No. 4 cause among women, killing around 800,000 people worldwide yearly.