Link between painkillers and breast cancer unclear

Taking ibuprofen or aspirin long term appears to be tied a heightened risk of developing breast cancer, a new study indicates, but at this point it is unclear if the association is cause-and-effect.

A causal link is perhaps doubtful because the pattern was not seen with the general class of painkillers called nonsteroidal antiinflammatory drugs or NSAIDS, to which aspirin and ibuprofen belong.

The findings, which appear in the Journal of the National Cancer Institute, are based on an analysis of data from 114,460 women enrolled in the California Teachers Study.

During follow-up from 1995 to 2001, a total of 2391 women were diagnosed with breast cancer.

Breast cancer Definition
Breast cancer is a malignant growth that begins in the tissues of the breast. Over the course of a lifetime, one in eight women will be diagnosed with breast cancer.

Using aspirin or any other NSAID more than once a week had no effect on breast cancer risk, unless such use lasted at least 5 years, Dr. Sarah F. Marshall, from the University of Southern California in Los Angeles, and colleagues report.

Long-term aspirin use was tied to an increased risk of breast cancer that was not hormone-driven, but to a slightly decreased risk of hormone-dependent disease, the researchers found.

There was also evidence that long-term ibuprofen use increased the risk of breast cancer, especially disease that had spread.

The authors estimate that 22 of the breast cancer cases diagnosed might be attributed to aspirin or ibuprofen use.

"These observations warrant further exploration because of the public health impact such readily available NSAIDs may have on breast cancer," Marshall's team concludes.

SOURCE: Journal of the National Cancer Institute, June 1, 2005.