NEW YORK (Reuters Health) - In women with a common mutation that slows aspirin metabolism, regular aspirin use reduces the risk of colorectal adenoma, a new study shows. But in women without the mutation, regular aspirin use was not associated with a significant reduction in colorectal polyps.
From 50% to 60% of the Caucasian population carries at least one copy of the variant gene, a single or tandem mutation in the uridine diphosphate glucuronosyltransferase 1A6 (UGT1A6) enzyme, Dr. Andrew T. Chan of Massachusetts General Hospital in Boston told Reuters Health.
Previous research has linked the mutation to a stronger effect of aspirin use on colorectal adenoma risk, he notes. “Our study extends these findings by demonstrating this in a group of patients in which aspirin data were assessed prospectively, which really minimizes the likelihood that patients with or without polyps recalled their aspirin use incorrectly,” Dr. Chan said.
The investigation, which included 1,062 women participating in the Nurse’s Health Study, also was able to evaluate the effects of aspirin use at a range of doses. The findings are published in the March 15th issue of the Journal of the National Cancer Institute.
In the 616 women with the gene variation, the researchers found that those who took two or more standard aspirin tablets each week reduced their risk of adenoma by 34%. The reduction was dose-dependent, with women taking more than seven tablets weekly cutting their risk 59%.
But in women with the normal genotype, aspirin did not produce a significant reduction in adenoma risk, and higher doses produced no increased benefit.
“I don’t think we’re prepared to say that it doesn’t benefit people with the normal gene at all, but it does seem to be a smaller benefit,” Dr. Chan said.
Before these findings can be applied clinically, he added, further studies are needed to determine if people with the gene variant are also more likely to experience side effects from aspirin, such as gastrointestinal bleeding. Such findings could help define the risk-benefit ratio of aspirin use for all patients.
Dr. Chan said his team also hopes to look at how the gene variation affects other outcomes related to aspirin use, such as the drug’s cardioprotective effects.
In the meantime, he added, the only proven colon cancer prevention method remains regular screening. “It’s still very important that people pursue recommended screening for prevention.”
Source: J Natl Cancer Inst 2005;97:457-460. [ Google search on this article ]
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