Association of Frequency and Duration of Aspirin Use and Hormone Receptor Status With Breast Cancer Risk.

摘要

Several cancers, breast cancer among them, appear to develop less often in persons taking aspirin or another nonsteroidal antiinflammatory drug (NSAID). These agents inhibit cyclooxygenase activity and, in turn, prostaglandin synthesis. Prostaglandins stimulate expression of the aromatase gene, thereby promoting estrogen synthesis. This population-based case-control study compared 1442 women with breast cancer and 1420 control women who gave in-person interviews in the years 1996 to 1997. More than 90% of the study and control women were white. Participants were asked about their use of aspirin, ibuprofen, and acetaminophen. Taking aspirin at least once a week for 6 months or longer ("ever use") was reported by 20.9% of case women and 24.3% of controls. Ever use of aspirin correlated inversely with the risk of breast cancer; the odds ratio (OR) was 0.8. A similar association was found for invasive breast cancer. No such association was evident for ibuprofen or acetaminophen. The risk reduction associated with ever using aspirin was evident in both pre- and postmenopausal women, but particularly the latter (OR, 0.77 compared with 0.83 for the premenopausal group). Daily use of aspirin, but not less frequent use, was inversely associated with breast cancer (OR, 0.72). No increase in risk was noted in women taking aspirin for 5 years or longer. Duration of use appeared to be less important than frequency of use. Increasing use of ibuprofen was not associated with a decreasing risk of breast cancer, nor did either the frequency or duration of acetaminophen use influence the risk. For aspirin users, a risk reduction was noted in women having hormone receptor-positive cancers (OR, 0.74) but not for those with receptor-negative tumors (OR, 0.97). This association was not solely a result of differences in menopausal status. These findings encourage the regular use of aspirin and other NSAIDs, especially by postmenopausal women, in an attempt to lower the risk of breast cancer.