Evaluation of effect-measure modification by family history score for the associations between physical activity and breast cancer incidence, by menopausal status, The Sister Study
| Family history score | Physical activity | N cases | Stratified HRa (95% CI) | Ratio of stratified HRs | P |
|---|---|---|---|---|---|
| Postmenopausal | |||||
| Low (<median) | <7 hours/week | 987 | 1.00 | ||
| ≥7 hours/week | 90 | 0.80 (0.64–0.99) | |||
| High (≥median) | <7 hours/week | 1,043 | 1.00 | ||
| ≥7 hours/week | 98 | 0.91 (0.74–1.11) | 1.14 (0.84–1.53) | 0.4 | |
| Low (<median) | IQR increase in MET-hours/week | 1,077 | 0.95 (0.88–1.01) | ||
| High (≥median) | IQR increase in MET-hours/week | 1,141 | 0.92 (0.86–0.98) | 0.97 (0.88–1.07) | 0.6 |
| Premenopausal | |||||
| Low (<median) | <7 hours/week | 108 | 1.00 | ||
| ≥7 hours/week | 7 | 0.78 (0.36–1.68) | |||
| High (≥median) | <7 hours/week | 333 | 1.00 | ||
| ≥7 hours/week | 31 | 1.34 (0.93–1.94) | 1.72 (0.73–4.02) | 0.2 | |
| Low (<median) | IQR increase in MET-hours/week | 115 | 1.02 (0.86–1.20) | ||
| High (≥median) | IQR increase in MET-hours/week | 364 | 1.10 (1.02–1.19) | 1.08 (0.90–1.31) | 0.4 |
↵aAdjusted for race, residence type, education, parity, alcohol use, and smoking status.