Antibiotics can help prevent stomach cancer in people who carry a common strain of bacteria known to cause ulcers, a study found.
The Chinese study adds to the already strong evidence that Helicobacter pylori bacteria can cause stomach cancer, a disease especially prevalent in Asia but far less common in the United States.
Still, experts said the findings do not solve the dilemma of whether and how to treat carriers of the bacteria.
The study involved 1,630 men and women from Fujian Province in southern China. All were carriers of H. pylori; hundreds of them already had precancerous lesions at the outset of the study.
Patients were randomly assigned to receive two weeks of treatment with antibiotics and an anti-ulcer drug, or a dummy medicine, and were followed for 7 1/2 years after that.
Among the 988 patients without precancerous lesions at the outset, none on the treatment got stomach cancer, compared with six in the placebo group.
The findings among those with precancerous lesions were not as clear-cut: Seven in the treatment group developed stomach cancer, versus 11 in the placebo group.
The study appears in Wednesday's Journal of the American Medical Association.
No. 1 cause of ulcers
H. pylori is estimated to affect as many as 90 percent of people in some developing nations and up to 50 percent of people in some industrialized countries, according to the World Health Organization. Chronic H. pylori is thought to cause stomach cancer, and doctors have come to believe since the early 1980s that it is the No. 1 cause of ulcers.
Stomach cancer is the fourth most common type of cancer worldwide and is diagnosed in about 870,000 people annually, according to the World Health Organization. The highest rates are in East Asia, including China, perhaps because of genetic reasons or a diet high in salt-cured foods.
In the United States, about 23,000 new cases are expected this year, according to the American Cancer Society.
The findings suggest that doctors should consider routine screening for such lesions in H. pylori patients in high-incidence areas, and treating the infections in patients with no precancerous lesions, said the authors, led by Benjamin Chun-Yu Wong of the University of Hong Kong.
But a JAMA editorial said the study does not resolve whether to employ widespread screening for the bacteria or for precancerous lesions.
While simple breath, blood and stool tests can identify whether someone has H. pylori, diagnosing precancerous lesions is more tricky and would probably require invasive and costly tests and biopsies, said the editorial by Dr. Julie Parsonnet, a Stanford University infectious-disease specialist, and David Forman of the University of Leeds in England.
Dr. Michael Brown, a gastroenterologist at Rush University Medical Center in Chicago, said routine H. pylori screening would not be cost-effective in the United States because the rates of infection and cancer are so low.