Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) had little effect on reducing the risk of breast cancer overall, however, the risk was notably lower among African-American and Caucasian women with long-term use, according to a study by the University of Hawaii and University of Southern California.

The researchers’ work is one of the first to explore the relationship between COX-2 inhibitors (aspirin and NSAIDs) and breast cancer in a multiethnic population.

The COX-2 enzyme is activated in response to inflammation and precancerous and cancerous tissues, and its inhibition has been associated with significant reduction in breast cancer tissue.

A few large research studies have also shown a reduction in risk of breast cancer among NSAID users.

 

While COX-2 research has found a promising association with NSAIDs and cancer, Jasmeet Gill, Ph.D., postdoctoral fellow in the Department of Etiology, and her colleagues found no associations between aspirin and other NSAID (ibuprofen, naproxen, indomethacin, etc) use and breast cancer risk, even if the women’s total NSAID use (aspirin plus other NSAIDs) was for 11 or more years.

There were two exceptions: African-American women cut their breast cancer risk by more than half if they took NSAIDs other than aspirin for 6 or more years, and Caucasian women likewise cut their cancer risk by 30 percent.

"The COX-2 research and the NSAID studies led us to consider whether anti-inflammatory drugs might have different associations with breast cancer risk across ethnic groups," said Gill.

"We are not sure why we didn’t see a reduction in breast cancer incidence for aspirin users as other studies have shown, but we are intrigued by the reduced risk we observed among African-American and Caucasian women who used other NSAIDs. We believe more studies with detailed dosage information need to be conducted to resolve the role aspirin and NSAIDs play in the inhibition of breast cancer development."

Gill cautioned that their study did not collect information on dose and frequency of aspirin or other NSAID use.

The researchers followed a cohort of 99,553 African-American, Caucasian, Japanese, native Hawaiian and Latina women from Hawaii and Los Angeles County between 1993 and 2002.

When examining the risk of breast cancer from aspirin and other anti-inflammatory drugs, they found that body mass, tumor stage, or age had no consistent effect on the NSAID-cancer association. 

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