Cancer From Germs

By ANDREW PURVIS

Could cancer be an infectious disease? In some cases the answer is at least partly yes. Viruses are thought to play a role in liver and uterine cancer and some forms of lymphoma. Now comes the news that bacteria may actually be a major culprit in the world's second most common malignancy: stomach cancer, which afflicts an estimated 700,000 a year worldwide.

In separate studies of 130,000 and 6,000 people, reported in the New England Journal of Medicine, researchers from Stanford and Kuakini Medical Center in Honolulu found that people infected with the bacterium Helicobacter pylori were three to six times as likely to develop stomach cancer over a 20-year period as those who were not infected. "This is not just a little risk we're talking about," says Stanford's Julie Parsonnet, though she points out that not everyone infected with the bacterium develops cancer. Indeed, the bug, which may enter the body through dirty water or human contact, is extremely common: it is present in the gut of 50% of Americans and of up to 90% of people in poorer regions of Asia and Latin America. Researchers believe chronic inflammation, caused by the bacterium, combines with other risk factors, including a salty diet low in fresh fruit and vegetables, to cause the cancer.

The nefarious H. pylori has also been linked to ulcers and gastritis -- inflammation of the stomach lining. Parsonnet and others believe that people with chronic duodenal ulcers should consider a course of antibiotics to knock out the bug rather than rely on costly medications like Tagamet and Zantac, which treat the symptoms, not the cause. Meanwhile, studies are under way in Colombia and Mexico to determine if a similar strategy of antibiotics could play a role in cutting the world's incidence of stomach cancer.

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CREDIT: TIME Chart

[TMFONT 1 d #666666 d {Source: International Journal of Cancer}]CAPTION: THE WORLD'S MOST COMMON FORMS OF CANCER