Aspirin and related anti-inflammatory drugs may help reduce the risk of breast cancer, and might even have a role in treating the disease, according to a new review of existing research on the topic.

But more research is needed to determine who would benefit the most from the drugs’ effects, and to understand how women might be able to take them without suffering harmful side effects such as stomach ulcers, Drs. Ian Fentiman and A. Agrawal from Guy’s Hospital in London conclude.

“My take-home message is not go and start taking aspirin,” Fentiman told Reuters Health. “We think our review has shown that aspirin can reduce the incidence of breast cancer, but, and a very big but, is that almost certainly this occurs when you take full doses of aspirin and not the small doses that you take for the prevention of heart disease.”

Such high doses carry the risk of causing stomach ulcers and related complications, the researcher said. “We just have to look again and say - what is the way that we could possibly give these agents in safe manner.”

In breast cancer, production of the COX enzyme is abnormally high. Aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) work by blocking this enzyme, so it is conceivable that they could help prevent or treat breast cancer, Fentiman and Agrawal note.

To investigate, the researchers reviewed several studies of NSAID use and breast cancer risk, and found that the drugs - especially aspirin - were tied to a “moderate reduction” in risk of the disease.

The data suggested that the drugs were effective in preventing estrogen receptor-positive tumors, which currently can be prevented and treated with drugs such as tamoxifen.

There also was some evidence that NSAIDs might be effective against tumors that did not carry estrogen receptors. “If that were the case that would be a big plus because at the moment we don’t have a way of preventing those cancers, which tend to be the more aggressive ones,” Fentiman said.

“NSAIDs may reduce breast cancer risk by 20 percent but the optimal type, dose and duration is still undetermined together with the feasibility of such an intervention in an at-risk population,” Fentiman and Agrawal conclude.

SOURCE: International Journal of Clinical Practice, March 2008.