Table 4. Vigorous exercise at baseline in relation to incidence of breast cancer by age, body mass index, parity, family history of breast cancer, menopausal status, and age.
| Hrs/wk | Cases | IRR* (95% CI) | Cases | IRR (95% CI) | P interaction | |
|---|---|---|---|---|---|---|
| Age <50 | Age ≥50 | |||||
| <1 | 287 | 1.00 (Ref.) | 486 | 1.00 (Ref.) | ||
| 1 | 55 | 0.77 (0.58, 1.03) | 62 | 0.90 (0.69, 1.18) | ||
| 2 | 63 | 0.84 (0.64, 1.11) | 86 | 1.12 (0.88, 1.41) | ||
| 3-4 | 75 | 0.83 (0.64, 1.08) | 84 | 1.02 (0.80, 1.29) | ||
| 5-6 | 31 | 0.74 (0.51, 1.08) | 38 | 1.02 (0.73, 1.43) | ||
| ≥7 | 26 | 0.57 (0.38, 0.86) | 37 | 0.91 (0.65, 1.27) | ||
| P trend = 0.003 | P trend = 0.98 | 0.44 | ||||
| BMI <30 | BMI ≥30 | |||||
| <1 | 418 | 1.00 (Ref) | 350 | 1.00 (Ref) | ||
| 1 | 71 | 0.86 (0.67, 1.11) | 45 | 0.83 (0.61, 1.13) | ||
| 2 | 101 | 1.09 (0.88, 1.36) | 48 | 0.85 (0.62, 1.15) | ||
| 3-4 | 110 | 0.98 (0.79, 1.21) | 49 | 0.88 (0.65, 1.19) | ||
| 5-6 | 50 | 0.96 (0.71, 1.30) | 18 | 0.74 (0.46, 1.19) | ||
| ≥7 | 41 | 0.73 (0.53, 1.01) | 22 | 0.81 (0.52, 1.25) | ||
| P trend = 0.24 | P trend = 0.08 | 0.28 | ||||
| Nulliparous | Parous | |||||
| <1 | 137 | 1.00 (Ref) | 636 | 1.00 (Ref) | ||
| 1 | 19 | 0.69 (0.40, 1.04) | 98 | 0.90 (0.73, 1.12) | ||
| 2 | 29 | 0.82 (0.54, 1.23) | 120 | 1.05 (0.86, 1.28) | ||
| 3-4 | 48 | 1.12 (0.80, 1.59) | 111 | 0.87 (0.71, 1.07) | ||
| 5-6 | 16 | 0.79 (0.46, 1.34) | 53 | 0.92 (0.69, 1.23) | ||
| ≥7 | 18 | 0.70 (0.48, 1.31) | 45 | 0.72 (0.53, 0.97) | ||
| P trend = 0.55 | P trend = 0.05 | 0.26 | ||||
| Family History Yes | Family History No | |||||
| <1 | 123 | 1.00 (Ref) | 650 | 1.00 (Ref) | ||
| 1 | 16 | 0.73 (0.43, 1.24) | 101 | 0.87 (0.70, 1.07) | ||
| 2 | 23 | 1.04 (0.66, 1.64) | 126 | 0.99 (0.82, 1.20) | ||
| 3-4 | 28 | 1.05 (0.68, 1.60) | 131 | 0.91 (0.75, 1.11) | ||
| 5-6 | 11 | 0.88 (0.47, 1.65) | 58 | 0.89 (0.68, 1.17) | ||
| ≥7 | 10 | 0.75 (0.39, 1.44) | 53 | 0.74 (0.56, 0.99) | ||
| P trend = 0.59 | P trend = 0.05 | 0.97 | ||||
| Premenopausal | Postmenopausal | |||||
| <1 | 238 | 1.00 (Ref) | 425 | 1.00 (Ref) | ||
| 1 | 52 | 0.88 (0.65, 1.19) | 47 | 0.81 (0.60, 1.09) | ||
| 2 | 63 | 0.99 (0.75, 1.31) | 65 | 1.01 (0.78, 1.31) | ||
| 3-4 | 74 | 0.99 (0.76, 1.29) | 65 | 0.94 (0.72, 1.22) | ||
| 5-6 | 32 | 0.89 (0.61, 1.30) | 27 | 0.85 (0.60, 1.33) | ||
| ≥7 | 24 | 0.64 (0.42, 0.98) | 32 | 0.94 (0.66, 1.36) | ||
| P trend = 0.13 | P trend = 0.55 | 0.76 | ||||
*
IRRs adjusted for age (single year), questionnaire cycle, years of education (≤12, 13-14, 16, ≥17), parity (0, 1, 2, ≥3), vegetable/fruit dietary pattern (quintiles), and meat/fried foods dietary pattern (quintiles)