Participant characteristics | Casesa (N = 1,129) | Controlsa (N = 1,229) | P b |
---|---|---|---|
Demographic factors | Â | Â | Â |
   Age (years) | 47.6 ± 8.0 | 47.2 ± 8.7 | 0.20 |
   Education (% high school or more) | 43.4% | 43.1% | 0.89 |
Reproductive risk factors | Â | Â | Â |
   Age (years) at menarche | 14.5 ± 1.6 | 14.7 ± 1.7 | <0.01 |
   Age (years) at menopausec | 48.2 ± 4.7 | 47.5 ± 4.9 | 0.04 |
   Age (years) at first live birthd | 26 ± 4.1 | 26.0 ± 3.8 | <0.01 |
Other risk factors | Â | Â | Â |
   Breast cancer among first-degree relatives (%) | 3.4 | 2.4 | 0.11 |
   Ever had breast fibroadenoma (%) | 9.7 | 5.1 | <0.01 |
   Body mass index (kg/m2) | 23.5 ± 3.4 | 23.2 ± 3.4 | 0.03 |
   Waist-to-hip ratio | 0.81 ± 0.06 | 0.80 ± 0.06 | <0.01 |
   Physically active during past 10 years (%) | 19.3 | 25.7 | <0.01 |