| Aspirin Users Show Lower Esophageal Cancer Risk |
| 来源:Reuters;添加日期:2003-1-30;编辑:ark |
January 28, 2003 01:08:33 PM PST,
New research suggests that aspirin and related painkillers may help protect against cancer of the esophagus, a relatively rare but often fatal disease.
The study found only an association between lower esophageal cancer risk and the use of non-steroidal anti-inflammatory drugs (NSAIDs)--and not a cause-and-effect relationship.Still, researchers say their findings warrant studies into whether NSAIDs can help prevent the cancer in certain people at heightened risk.
For example, a small percentage of people with a condition called Barrett's esophagus will develop esophageal cancer. Barrett's esophagus develops in some people with acid reflux disease due to cumulative damage to the esophageal lining.
At first glance, an association between NSAID use and lower esophageal cancer risk might seem odd: One of the medications' well-known side effects is irritation of the gastrointestinal tract, including ulcers and bleeding. The American Cancer Society ( news - web sites)'s Dr. Michael J. Thun told Reuters Health that several years ago, he would have doubted the association found in the new study.
However, he said, lab research in recent years has given a "strong biological basis" to the idea that NSAID use might lower the risk of some cancers, including those of the colon and prostate.
The reason has to do with the drugs' ability to fight inflammation, which is thought to play an important role in the complex cancer process.
Specifically, NSAIDs block the activity of an enzyme called COX-2, which is suspected of aiding cancer-cell growth. Studies show that COX-2 activity is induced early in the development of some tumors, including those of the esophagus.
Now the new research--a review of nine earlier studies--shows that people who reported any use of aspirin or other NSAIDs had a roughly 40% lower annual risk of esophageal cancer.And more frequent use was associated with greater protection than "intermittent" use was, Dr. Douglas A. Corley, of the University of California, San Francisco, and his colleagues found.Broken down by medication type, aspirin showed the strongest protective effect, while other NSAIDs were "borderline protective," according to findings published in the January issue of Gastroenterology.
However, aspirin and other older-generation NSAIDs, such as ibuprofen and naproxen, also block the COX-1 enzyme--a feature that means they can irritate the gastrointestinal tract.So, the current findings could, in part, reflect the fact that people with acid reflux or other GI problems often avoid NSAIDs. If this is true, it would create the false impression that NSAIDs were helping to prevent cancer.Such "reverse causation" is a possibility, Thun notes in an accompanying editorial."What's missing," he explained in an interview, "is the final proof" that NSAID use directly lowers esophageal cancer risk.Because regular NSAID use can cause GI problems, Thun said, doctors need a "high degree of certainty" that the drugs can safely lower cancer risk before they recommend them for that purpose.
Among the "major questions" that future studies must answer, he noted, are what NSAID dose and what duration of use might do the job.
So far, three trials of NSAIDs for esophageal cancer prevention have gotten underway.
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