Use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs)
has been associated with a decrease in the risk of several cancers, including
breast cancer. NSAIDs inhibit cyclooxygenase activity and thereby reduce prostaglandin
synthesis; prostaglandins stimulate aromatase gene expression and thereby
stimulate estrogen biosynthesis. Given the importance of estrogen in the pathogenesis
of breast cancer, the ability of aspirin and other NSAIDs to protect against
breast cancer could vary according to hormone receptor status.
To determine the association between the frequency and duration of use
of aspirin and other NSAIDs and breast cancer risk and to investigate whether
any observed association is more pronounced for women with hormone receptor–positive
Design, Setting, and Patients
Population-based case-control study of women with breast cancer, including
in-person interviews conducted on Long Island, NY, during 1996-1997 (1442
cases and 1420 controls).
Main Outcome Measure
Incident invasive and in situ breast cancer by aspirin and NSAID use
and hormone receptor status.
Ever use of aspirin or other NSAIDs at least once per week for 6 months
or longer was reported in 301 cases (20.9%) and 345 controls (24.3%) (odds
ratio [OR], 0.80; 95% confidence interval [CI], 0.66-0.97 for ever vs nonusers).
The inverse association was most pronounced among frequent users (≥7 tablets
per week) (OR, 0.72; 95% CI, 0.58-0.90). The results for ibuprofen, which
was used by fewer women on a regular basis, were generally weaker (OR, 0.78;
95% CI, 0.55-1.10 for <3 times per week vs OR, 0.92; 95% CI, 0.70-1.22
for ≥3 times per week). Use of acetaminophen, an analgesic that does not
inhibit prostaglandin synthesis, was not associated with a reduction in the
incidence of breast cancer. The reduction in risk with aspirin use was seen
among those with hormone receptor–positive tumors (OR, 0.74; 95% CI,
0.60-0.93) but not for women with hormone receptor–negative tumors (OR,
0.97; 95% CI, 0.67-1.40).
These data add to the growing evidence that supports the regular use
of aspirin and other NSAIDs (which may operate through inhibition of estrogen
biosynthesis) as effective chemopreventive agents for breast cancer.