UNE RAISON DE PLUS DE PRENDRE DE L'ASPIRINE ! ! !
Studies Find Aspirin Can Lower Risk of Precancerous Colon Polyps By GINA KOLATA http://www.nytimes.com/2003/03/06/health/06COLO.html For the first time, researchers have shown in the most rigorous kind of studies that aspirin can reduce the risk of developing colon and rectal polyps, the precursors of almost all colon cancer. That is the finding of two clinical trials, which, taken together, are one of the few cancer prevention efforts to bear fruit thus far. And since they involve colon and rectal cancer, second only to lung cancer among leading causes of cancer-related deaths in this country, many medical experts are elated. But the experts also caution that people still need to be screened whether or not they take aspirin. While the newly reported studies found that aspirin meant polyps in fewer patients, it did not prevent all polyps. Further, the researchers say that while they would encourage some patients at high risk of colon cancer to take aspirin daily � either a regular pill or a baby aspirin � those at average risk may face more risks from the drug than benefits. Aspirin can inhibit blood clotting, a circumstance that can lead to strokes, or irritate the stomach lining, leading to ulcers. "Researchers and clinicians understand that this is a landmark," said Dr. Thomas Imperiale, a professor at the Indiana University School of Medicine, who was not involved in either study. "These are two randomized controlled clinical trials," the most scrupulous form of medical research, in which people are randomly assigned to take a test drug or placebos, and their outcomes compared. "But," Dr. Imperiale added, the new studies "are on a fairly select group of people." The studies involved high-risk patients, for whom adenomas � protruding growths on the inside of the rectum and colon that are commonly called polyps � are of particular concern. Few polyps turn into cancers, but since no one knows which ones will, doctors say it is important to find them and slice them off the wall of the colon or rectum. The studies did not address the question of whether aspirin was helpful for people at average risk of colon cancer. "These studies involved patients at greater-than-average risk," said Dr. Ernest Hawk, chief of gastrointestinal cancer prevention research at the National Cancer Institute. "That changes the risk-benefit equation. We can tolerate a little risk if we have more benefits." Both studies are being published today in The New England Journal of Medicine. One, directed by Dr. Robert Sandler of the University of North Carolina, involved 635 patients who had had colon or rectal cancer. Half took a regular, 325-milligram pill of aspirin each day, and the others took a placebo. This study ended early, because the results were so definitive: after patients had taken their assigned pills for an average of 31 months, 17 percent of those taking aspirin had new polyps, compared with 27 percent in the placebo group. The other study, directed by Dr. John Baron of Dartmouth-Hitchcock Medical Center in Lebanon, N.H., involved 1,121 patients who had already had polyps, which had been removed. These patients were randomly assigned to take a placebo, a regular aspirin or a low-dose, 81-milligram aspirin each day. Three years later, at the study's end, 38 percent of the patients taking the baby aspirin had polyps, compared with 47 percent of patients taking a placebo and 45 percent of those taking regular aspirin. The researchers said they were baffled by the baby aspirin's superiority to the regular aspirin in the outcome, and by the little difference in results between the regular aspirin and the placebo. In any case, both doses of aspirin reduced the risk of more ominous-appearing large polyps. Such polyps occurred in 12.9 percent of patients taking a placebo, in 10.7 percent of those taking a regular aspirin and in 7.7 percent of those taking a baby aspirin. Dr. Hawk said he was encouraged that aspirin had not led to bleeding problems in the two studies. "Aspirin was very well tolerated," he said. "It was not significantly different from the placebo." Another colon cancer expert, Raymond N. DuBois, who directs the cancer prevention program at the Vanderbilt-Ingram Cancer Center in Nashville, added that while the patients in the studies did not take drugs to protect themselves from gastrointestinal bleeding, there was an effective method of such protection: people can take an over-the-counter antacid, like Pepcid, that contains a histamine blocker. Colon cancer specialists say that while almost all colon and rectal cancers start as polyps, most polyps will never become cancers. "These adenomas are very common: if you do autopsies on older adults, perhaps half would have them," Dr. Baron said. "It is widely thought that to traverse the whole cancer pathway, from adenoma to cancer, takes 15 or 20 years or more. Certainly during the lifetime of a person, a few percent or less of adenomas go on to cancer." The advantage of preventing polyps, he added, is that doctors can occasionally miss them in screening tests, so preventing them helps cut the risk that a benign growth will escape detection and turn deadly. In addition, with fewer polyps, patients can be spared removal, which on rare occasions can cause bleeding. The studies were undertaken after a growing body of evidence strongly suggested that aspirin might impede the growth of colon and rectal cancer. The story dates from the late 1970's, when Dr. William R. Waddell of the University of Colorado Health Sciences Center noticed by chance that when he gave a similar drug, sulindac, to a handful of patients with an inherited disorder that leads to hundreds of polyps, their polyps mostly disappeared. Few believed him, until, in 1993, a colon cancer specialist at Johns Hopkins, Dr. Francis M. Giardiello, published a paper in The New England Journal of Medicine reporting that he had confirmed the observation in a small clinical trial with 22 of his own patients who had the inherited disorder, familial adenomatous polyposis. In the meantime, Dr. DuBois, of Vanderbilt-Ingram, noticed that in large population studies, people who happened to be taking aspirin daily for other ailments, like arthritis, had half as much colon and rectal cancer as the rest of the population. Soon, others began finding presumptive though not conclusive evidence. "There are 30 published studies, involving millions of individuals, and 28 suggest benefit from aspirin and aspirinlike drugs," Dr. Hawk said. Even the mechanism is understood, Dr. DuBois said. Aspirin inhibits an enzyme in cells, cyclooxygenase-2. Dr. DuBois and others have shown that this enzyme is involved in the development of cancer, allowing cells to make prostaglandins. Prostaglandins act like local hormones, spurring cell growth and preventing cell death, whether the cells are normal or cancerous. Prostaglandins also attract blood vessels to tumors, helping to keep them nourished. A growing body of evidence suggests that aspirin and other drugs that inhibit the same enzyme might protect against other cancers as well, Dr. Hawk said, though "the most compelling and most consistent evidence involves colon cancer." __________________________________________________ Do you Yahoo!? Yahoo! Tax Center - forms, calculators, tips, more http://taxes.yahoo.com/ --- URG-L Aimeriez-vous obtenir une adresse de courriel @URGENCES.CA? Suivez-le lien http://www.groupegiroux.com/messagerie pour de plus amples informations.
