Low-Dose Aspirin May Lower Colon Cancer Risk
Article date: October 22, 2010
By Eleni Berger
Daily use of low-dose aspirin can lower the risk of developing colon cancer and the risk of dying from it, according to a new long-term study.
That's potentially good news for people who already take aspirin to reduce their risk of heart attack or stroke. But it doesn't mean otherwise healthy people should start popping baby aspirin just to try to prevent colon cancer, according to American Cancer Society experts.
Significant reduction in incidence and mortality
The new study looked at the combined results of 4 clinical trials that randomly assigned more than 14,000 people to take daily aspirin or a placebo for periods of about 3 to 7 years, depending on the trial. The original studies were meant to find out if aspirin could prevent cardiovascular events like stroke or blood clots, but included enough data to allow the researchers to investigate colon cancer cases and deaths, too.
After 20 years of follow-up, colon cancer cases were reduced by 24% and colon cancer deaths by 35% in the group assigned to take aspirin compared to the placebo group.
Daily low doses (75mg - 300 mg) of aspirin were just as effective as higher doses. Taking aspirin for 5 years or longer reduced risk more than taking aspirin for less time.
The research team was led by Peter M. Rothwell, FMedSci, of the University of Oxford in England. The results were published this week in The Lancet.
Aspirin as cancer prevention not currently recommended
Previous research has shown that daily high doses of aspirin can reduce the risk of colon cancer, notes Eric Jacobs, PhD, strategic director of epidemiology at the American Cancer Society.
"The new study now fills an information gap by demonstrating that the lower doses of aspirin typically taken for heart disease prevention are adequate to reduce risk not only of colorectal polyps, but also of colorectal cancer," he adds.
Nevertheless, the American Cancer Society does not recommend taking aspirin as a colon cancer prevention measure, Jacobs emphasizes.
"Aspirin, even at low doses, substantially increases the risk of serious, occasionally fatal, gastrointestinal bleeding," he says. "Current evidence suggests that very low doses of aspirin, such as 81 mg, may increase risk of gastrointestinal bleeding as much, or nearly as much, as higher doses, such as 500 mg. Decisions about whether an individual should start taking aspirin should continue to be made by balancing the benefits of aspirin use in preventing cardiovascular disease against the risks of gastrointestinal bleeding, taking into account each individual’s medical history and risk factors."
The new study did not look at the side effects from taking aspirin.
Screening still crucial
One proven method for preventing colon cancer is to get screened for the disease. "It is still very important to get screened for colorectal cancer so that colorectal polyps can be detected and removed before they ever turn into cancer," Jacobs says.
The American Cancer Society recommends regular colon cancer screening for men and women starting at age 50. People who are at a higher-than-average risk of the disease (such as those with a family history of colon cancer) may need to begin getting tested earlier, or have more frequent tests.
That goes even for people who take aspirin regularly for other reasons, Jacobs notes. "Aspirin use will not prevent most cases of colorectal cancer."
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