Some strains of a common bacterium harbor a gene that may underlie a huge share of stomach cancers, a new study finds.
The bacterium, Helicobacter pylori, has been linked to gastritis, ulcers, and stomach cancer. But while H. pylori infects, by some estimates, more than half the global population, there are only about a million people worldwide with stomach cancer. Apparently, therefore, not all strains of the microbe have malignant potential. Over the past decade, scientists have traced this discrepancy to H. pylori 's genetic makeup (SN: 11/30/02, p. 341). In particular, they've zeroed in on strains that carry a gene dubbed cagA, for cytotoxin-associated gene.
In the new study, researchers obtained frozen tissue samples snipped from the stomach linings of 2,145 people participating in a cancer-screening program in Venezuela. The samples revealed that 16 percent of the volunteers didn't have a