Aspirin may reduce mortality rate among women with breast cancer

Women who have breast cancer and who take aspirin 2 to 5 days per week may significantly reduce their risk of dying from the disease and of experiencing its metastasis, according to researchers at Brigham and Women's Hospital in Boston, Massachusetts.

The prospective observational study was based on responses from 4,164 female registered nurses enrolled in the Nurses' Health Study who had been diagnosed with stages I, II, or III breast cancer between 1976 and 2002. All were followed until June 2006 or until they died, whichever came first. Within the study population, 400 recurrences were reported, and 341 of these women died of their disease. Researchers focused on patient-reported aspirin and other nonsteroidal anti-inflammatory drug use, stratifying data according to the number of days of aspirin use per week (ie, 0 days, 1 day, 2-5 days, and 6-7 days) and assessing use 1 year from diagnosis and at regular intervals thereafter.

After adjusting for stage, diet, physical activity, body mass index (BMI), weight change, reproductive factors, treatment (chemotherapy, radiation, and hormonal therapy), smoking status, and calendar year and applying Cox proportional hazards models with months since diagnosis as the underlying time variable to calculate relative risk (RR) and 95% confidence intervals (CI), researchers found that compared with those who did not use aspirin, the adjusted RR of women who used aspirin 1 day per week was 1.07 (95% CI, 0.62-1.33), 2 to 5 days per week was 0.29 (95% CI, 0.16-0.52), and 6 to 7 days, was 0.36 (95% CI, 0.24-0.54; test for linear trend, P<.001). The association was unaffected by stage, menopausal status, BMI, or estrogen receptor status.

Noting that the Nurses' Health Study found no association between aspirin use and breast cancer incidence, the authors suggest that aspirin may influence proximal rather than distal events in the cancer pathway, possibly by lowering serum estradiol or by elevating tissue levels of prostaglandins in hormone receptor-negative tumors. In addition, it may prevent early metastasis as a function of COX-2 overexpression.

Holmes MD, Chen WY, Li L, Hertzmark E, Spiegelman D, Hankinson SE. Aspirin intake and survival after breast cancer. J Clin Oncol. 2010. Epub ahead of print. http://jco.ascopubs.org/cgi/doi/10.1200/JCO.2009.22.7918/. Accessed February 17, 2010.