[MOL] Genes linked to increased risk of stomach cancer.... [02410] Medicine On Line


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[MOL] Genes linked to increased risk of stomach cancer....



Genes linked to increased risk of stomach cancer

NEW YORK, Mar 22 (Reuters Health) -- Although people infected with Helicobacter pylori bacteria are at increased risk of ulcers and stomach cancer, it is not clear why only some of them go on to develop cancer. Now, an international team of researchers reports one possible reason. They found that infected individuals who also have particular forms, or alleles, of a gene called interleukin-1 (IL-1) are at increased risk of gastric cancer.

H. pylori, found in the stomachs of about half the world's population, causes inflammation of the stomach lining. This can either lead to ulcers or decreased production of stomach acid and stomach cancer -- the second most common cancer. IL-1 also causes inflammation, and researchers suspect it also reduces stomach acid production.

Dr. Emad M. El-Omar from the National Cancer Institute in Bethesda, Maryland, and colleagues studied two populations to see if particular IL-1 alleles influenced the risk of developing stomach cancer. They studied 149 first-degree relatives of stomach cancer patients and, for comparison purposes, 100 newborns from Scotland. The team also studied 393 Polish people with stomach cancer and 430 people without the cancer.

Among individuals infected with H. pylori, those with low levels of stomach acid were more likely to carry two particular alleles of the IL-1 gene, which were also associated with a higher risk of gastric cancer. The investigators estimated that 31% of gastric cancers were due to one allele, compared with 18% for the other allele, and together they accounted for 38% of stomach cancer cases.

El-Omar's group suggests in the March 23rd issue of the journal Nature that because IL-1 causes inflammation, this may initially wash H. pylori out of the stomach. But since it also decreases the secretion of stomach acid, this could worsen damage to the stomach lining by allowing the accumulation of bacterial toxins and by-products of inflammation. This can lead to DNA damage and stomach cancer, although other genetic and environmental factors also appear to influence cancer risk.


Warmly, lillian
 
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