| PA level |
---|
 | Very low | Low | Moderate | High | Very high |
P
trend
|
---|
At age 14
| Â | Â | Â | Â | Â | Â |
N casesb
| 32 | 170 | 609 | 599 | 302 | Â |
RR (95% CI)a
| 0.77 (0.54, 1.10) | 0.80 (0.68, 0.95) | 1.0 (ref) | 1.02 (0.91, 1.14) | 1.04 (0.90, 1.19) | 0.008 |
At age 30
| Â | Â | Â | Â | Â | Â |
N casesb
| 34 | 206 | 746 | 548 | 189 | Â |
RR (95% CI)a
| 1.16 (0.82, 1.64) | .99 (0.85, 1.16) | 1.0 (ref) | 0.97 (0.87, 1.09) | 0.91 (0.78, 1.08) | 0.23 |
At enrollment
| Â | Â | Â | Â | Â | Â |
N cases | 105 | 401 | 722 | 443 | 96 | Â |
RR (95% CI)a
| 1.06 (0.86, 1.30) | 1.05 (0.93, 1.19) | 1.0 (ref) | 1.04 (0.92, 1.17) | 0.91 (0.73, 1.12) | 0.40 |
-
aMultivariable model with RR and 95% CI used the attained age as the underlying time variable. Covariates adjusted for in the model were height, body mass index, smoking status, smoking duration (pack years), age at menarche, use of oral contraceptives, age at first birth, parity, use of hormone replacement therapy, self-reported disease and history of breast cancer in the participant’s mother.
-
bThe total number of breast cancer does not add up due to by missing information on PA level at younger ages, age 14 to age 30 n = 77,272, age 14 to enrollment n = 77,623 and age 30 to enrollment n = 78,477.
- RR: relative risks; CI: confidence intervals.