March 10, 2008 -- Regular use of aspirin and possibly other nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce breast cancer risk by as much as 20%, but it is still not clear if the risks of long-term treatment outweigh the potential benefits, a review of the research shows.
The good news from the studies is that aspirin does seem to protect against breast cancer, study researcher Ian Fentiman, MD, of London's Guy's Hospital, tells WebMD.
The bad news is that the protective effect was not seen with lower doses of the pain reliever, like those routinely given to protect against heart attacks and strokes, he says.
Long-term use of aspirin carries the risk of serious side effects, such as stomach bleeding and ulcers.
There have not been enough studies of other NSAIDs, like the Cox-2 inhibitors (such as Celebrex), to determine if they too have protective benefits, Fentiman says.
"What we have done with this review is say, 'Yes, the NSAIDs have promise for breast cancer prevention,'" Fentiman says. "But there are many unanswered questions with regard to toxicity and how we can best avoid it."
Aspirin and Breast Cancer
Fentiman and colleague Avi Agrawal reviewed 21 studies involving more than 37,000 women published between 1980 and 2007.
Eleven of the studies included women with breast cancer, while the remaining 10 compared women who had the disease with those who did not.
The studies showing a protective benefit for NSAIDs against breast cancer were found to be of higher quality than those showing no link between NSAID use and breast cancer risk.
Additional research is needed to confirm the effect and to determine if the cancer prevention benefits of taking specific NSAIDs outweigh the risks.
A study involving daily treatment with the Cox-2 inhibitor Celebrex is now under way in Europe to determine if the drug can benefit breast cancer patients.
Cox-2 drugs carry less gastrointestinal risk than that seen with aspirin and other NSAIDs, but there is concern about cardiovascular risk. The best-selling Cox-2 arthritis drug Vioxx was voluntarily withdrawn from the market in September 2004 following reports of an increased incidence of heart attacks and strokes among users.
Developing Targeted NSAIDs
A targeted NSAID that could protect against breast cancer with little risk is the goal, Fentiman says.
"I would not want to give women the idea that aspirin is the answer for everything," he says.
Harvard Medical School researcher Julie E. Buring, ScD, tells WebMD that the message to women regarding NSAIDs and breast cancer risk is far from clear.
Buring and colleagues followed women who took a low-dose aspirin regularly every other day and women who didn't for 10 years as part of the Women's Health Study. They found no evidence that low-dose aspirin had any impact on breast cancer risk.
"Because of the risks, if higher doses are required this is likely to be seen as a prevention strategy only for those women at the highest risk [for breast cancer]," she says.