Table 2. Relative risks (RR) of breast cancer (n=849) by total activity among premenopausal women in the NHS II cohort, 1989–1999.
|
NHS | |||||
|---|---|---|---|---|---|
| Person-years (thousands) | Cases | Age-adjusted RR (95% CI) | Multivariatea without BMI RR (95% CI) | Multivariateb with BMI RR (95% CI) | |
| Total activity (MET-h week−1) | |||||
| <3 | 106.1 | 95 | 1.00 | 1.00 | 1.00 |
| 3–8.9 | 217.5 | 210 | 1.07 (0.84–1.37) | 1.05 (0.82–1.34) | 1.05 (0.82–1.33) |
| 9–17.9 | 225.5 | 197 | 0.99 (0.77–1.26) | 0.96 (0.75–1.23) | 0.95 (0.74–1.21) |
| 18–26.9 | 140.2 | 131 | 1.08 (0.83–1.41) | 1.05 (0.80–1.37) | 1.03 (0.79–1.35) |
| ⩾27 | 244.8 | 216 | 1.10 (0.86–1.40) | 1.07 (0.84–1.36) | 1.04 (0.82–1.33) |
| P for linear trend | 0.57 | 0.69 | 0.86 | ||
a
Adjusted for age, height, alcohol intake, age at menarche, age at first birth, oral contraceptive use, history of benign breast disease, and mother or sister with breast cancer.
b
Adjusted for the factors listed above plus BMI.