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Aspirin use associated with reduced risk of breast cancer

The JAMA Network Journals

Women who report regular use of aspirin appear to have a reduced risk of breast cancer, according to a study in the May 26 issue of The Journal of the American Medical Association (JAMA).

While cancer epidemiology and prevention have traditionally focused on the identification and modification of lifestyle factors that may increase or decrease the risk of various cancers, much recent attention has been centered on chemoprevention, the use of chemical agents to prevent or inhibit the carcinogenic process, according to background information in the article. Use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) has been associated with a decrease in the risk of several cancers, including breast cancer. Given the importance of estrogen in the pathogenesis of breast cancer, the ability of aspirin and other NSAIDs to protect against breast cancer could vary according to hormone receptor status.

Mary Beth Terry, Ph.D., of Columbia University, New York, and colleagues conducted a study to determine the association between the frequency and duration of use of aspirin and other NSAIDs and breast cancer risk and whether any observed association is more pronounced for women with hormone receptor-positive breast cancers. The study, which included in-person interviews, was conducted during 1996-1997. There were 1,442 breast cancer cases and 1,420 controls.

The researchers found that ever use of aspirin or other NSAIDs at least once per week for 6 months or longer was reported in 301 cases (20.9 percent) and 345 controls (24.3 percent) with a 20 percent lower risk of breast cancer for ever use vs. nonusers. "The inverse association was most pronounced among frequent users [7 or more tablets per week, 28 percent lower risk]. The results for ibuprofen, which was used by fewer women on a regular basis, were generally weaker [22 percent lower risk for less than 3 times per week vs. 8 percent lower risk for 3 times or more per week]. Use of acetaminophen, an analgesic that does not inhibit prostaglandin synthesis, was not associated with a reduction in the incidence of breast cancer. The reduction in risk with aspirin use was seen among those with hormone receptor-positive tumors [26 percent lower risk] but not for women with hormone receptor-negative tumors," the authors write.

"Our data, supported by other epidemiologic and laboratory evidence, bolster the case for the use of aspirin and NSAIDs as chemopreventive agents against breast cancer, particularly among postmenopausal women. The mechanisms are probably distinct from those that are protective against gastrointestinal tract cancers. There are many attractive features to such a chemopreventive agent, including its ease of use and association with reducing risk of other health outcomes. The potential benefits need to be balanced against potential harmful effects of long-term aspirin use such as peptic ulcer disease and gastrointestinal bleeding," the researchers conclude. (JAMA. 2004;291:2433-2440. Available post-embargo at


Editor's Note: This work was supported in part by grants from the National Cancer Institute and the National Institute of Environmental Health Sciences.


In an accompanying editorial, Raymond N. DuBois, M.D., Ph.D., of the Vanderbilt University Medical Center, Nashville, Tenn., writes that the observation that receptor-positive tumors are more responsive to aspirin is consistent with previous findings. "This association needs to be confirmed before clinicians can make any definite recommendations to patients at risk for breast cancer. However, it does appear that there is emerging evidence supporting a protective effect of aspirin in estrogen receptor-positive and progesterone receptor-positive breast cancers.

"Despite the longstanding and ubiquitous nature of aspirin use, researchers are still exploring the clinical outcome of aspirin treatment in humans. Unfortunately, all the answers are not available and current information is insufficient to make any definite recommendations to patients. Women who take daily aspirin for cardiovascular indications may gain additional benefits with regard to reduction in their risk for certain cancers, such as hormone receptor-positive breast cancer. However, the optimal aspirin dose or regimen required to achieve a maximal reduction in cancer risk remains unknown," Dr. DuBois concludes. (JAMA. 2004;291:2488-2489. Available post-embargo at

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