Table 3

Association between aspirin and NSAID use and incident breast cancer

No. of casesTotal person-yearsAge-adjusted RR95% CIMultivariate-adjusted RRa95% CI
Aspirin or NSAID useb
 Any use749156,0820.860.73–1.020.800.67–0.95
Aspirin use
 Any use638137,2320.820.71–0.940.820.71–0.95
 Any use38375,0411.060.93–1.210.980.85–1.14
Aspirin use
 <1 per week25652,9560.850.72–1.030.870.72–1.04
 1 per week6010,4581.010.76–1.331.090.81–1.46
 2–5 per week15533,7430.810.67–0.980.800.65–0.99
 6+ per week16740,0750.730.60–0.880.710.58–0.87
P trend = 0.0016P trend = 0.0011
 <1 per week15129,1281.080.90––1.31
 1 per week155,9780.520.31–0.870.470.26–0.83
 2–5 per week7915,5071.060.84–1.340.930.71–1.21
 6+ per week138189,2131.170.97–1.411.010.83–1.25
P trend = 0.22P trend = 0.63
  • a Adjusted for age (continuous), BMI (continuous), estrogen use (current or not current), family history of breast cancer (yes or no), benign breast disease (yes or no), multivitamin use (yes or no), NSAID use five categories), mammography (yes or no), and waist:hip ratio (continuous).

  • b Aspirin analyses are adjusted for NSAIDs, and NSAID analyses are adjusted for aspirin use.