WASHINGTONUse of nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce risk of colon cancer, but apparently has little or no impact on breast cancer risk, said Patricia F. Coogan, ScD, of the Slone Epidemiology Unit, Boston University School of Medicine, Brookline, Mass.
There is a handful of animal evidence that NSAIDs can prevent the initiation and promotion of mammary tumors in rodents, Dr. Coogan said at the Department of Defenses Era of Hope conference. But the epidemiological evidence in humans is inconsistent and scanty.
The role for NSAIDs in cutting risks of colon cancer is clear from both animal studies, the Nurses Health Study, and many other studies, Dr. Coogan said. NSAIDs probably prevent colon cancer by inhibiting the production of prostaglandins, she added.
To test the possible effects of NSAIDs on breast cancer, Dr. Coogan and her colleagues used data collected from patients admitted to hospitals in four cities: Baltimore, Boston, New York, and Philadelphia. Earlier case-control data from the same study had shown a significantly reduced risk of large bowel cancer (odds ratio, 0.5) among regular aspirin users.
This time, Dr. Coogans group compared records of 6,558 patients with breast cancer with those of cancer controls (N = 3,296) and noncancer controls (N = 2,925). The cancer controls did not have breast cancer or any cancer such as colon cancer with a known relationship to NSAID use.
Dr. Coogan and her colleagues concentrated on patients who used NSAIDs regularly for more than a year prior to admission, and at least four times a week for 3 months.
Initially, a reduction in breast cancer risk (0.7) was found among regular users of NSAIDs, but this reduction was driven only by data from Boston and only during the first 4 years of the study. Once the 608 Boston patients were excluded, the odds ratio for regular NSAID use was 0.9 with both cancer and noncancer controls.