Long-Term Aspirin Use Seems to Protect Against Colorectal Lesions
TUESDAY Feb. 10, 2009 -- Prolonged use of low-dose aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) appears to reduce the risk of precancerous lesions that can lead to colorectal cancer.
That's the conclusion of a new study of people at high risk for the disease.
"It's increasingly clear, and arguably proven, that NSAID drugs do interfere with the development of cancer in the large bowel," said study co-author Dr. John A Baron, a professor of both medicine and community and family medicine at Dartmouth Medical School.
"And this study," he added, "is a building block in our understanding of all that because it shows two things: One, if you take the NSAID drug for a while and then stop, you won't get a big rebound in terms of adenoma tumor risk. And two, if you don't stop taking an NSAID, but instead continue its use over time, the protective benefit will continue."
Baron and his colleagues presented their findings in the Feb. 18 issue of the Journal of the National Cancer Institute.
For the study, the researchers focused on people who had embarked on the long-term use of aspirin as part of the Aspirin/Folate Polyp Prevention Study. The more than 1,100 participants were considered at high risk for developing colorectal cancer because of a history of polyp development. After enrolling between 1994 and 1998, all were tracked for three years while regularly taking either 81 milligrams or 325 milligrams of aspirin, or a placebo.
The result: The low-dose aspirin reduced the risk of developing colorectal polyps.
Baron and his colleagues then continued to track 850 of the patients for an average of four years, until each underwent a follow-up colonoscopy. During this time, aspirin use was monitored and classified as either "sporadic" (less than two days a week), "moderate" (two to four days a week), or "frequent" (more than four days a week).
Patients who'd initially been assigned to low-dose aspirin in the first trial and continued to take the drug on a "frequent" basis had a 13 percent lower risk for developing precancerous lesions (known as colorectal adenomas), compared with those who had initially taken a placebo and then went on to use NSAIDs "sporadically." The risk difference between the two groups was approximately 27 percent versus 40 percent, the study found.
The researchers also saw a similar risk spread between "sporadic" and "frequent" users of higher-dose (325 mg) aspirin, but they said the difference did not appear statistically significant.
The researchers also noted that the protective benefit of aspirin for a few years appeared to continue for some time among those who stopped taking the drug.
Baron cautioned, however, that NSAID drugs such as aspirin should be taken advisedly because of the gastro-intestinal side effects.
"It's a genuine concern. And that leads to the issue that for any drug or any intervention, you have to consider all the possible outcomes, good and bad, that may ensue," he said.
"Aspirin, for example, has a lot of benefits," Baron added. "It reduces the risk for cardiovascular disease, certainly among people who have had a history of previous stroke or heart attack. But aspirin, like all the NSAIDs, has the problem of prompting GI bleeding and GI heartburn, and also infrequently ulcers.
But Dr. Jerald D. Wishner, director of colon and rectal surgery at Northern Westchester Hospital Center in Mount Kisco, N.Y., said high-risk patients shouldn't turn to NSAIDs instead of routine screenings, such as a colonoscopy.
"I think it is appropriate to recommend NSAIDs to our patients, because if I can reduce the risk by 10 to 15 percent, and all it involves is taking an aspirin a day, who wouldn't sign up for that?" he said. "But we're talking about a high-risk group here. So, at the same time, we have to advise these patients that they are still at a higher risk and recommend that they continue to come in for follow-up screenings as they would if they weren't talking the aspirin."
In related findings published in the same issue of the journal, an international team of researchers reported that regular aspirin use at doses ranging from 81 milligrams to 325 mg appeared to collectively lower the absolute risk for developing any kind of precancerous colorectal lesion by almost 7 percent. And in relative terms -- when compared with taking no NSAIDs at all -- those patients taking aspirin achieved a 28 percent reduction in their risk for developing advanced lesions.
For more on colorectal cancer, visit the U.S. National Cancer Institute.
Posted: February 2009