Table 4.
Relationship between recreational physical activity (MET-hours per week) at baseline and risk of ER+ and triple-negative breast cancer
| Non-cases | Cases* |
|||||
|---|---|---|---|---|---|---|
| ER+ | TN | |||||
| n (%) | n (%) | HR (95% CI)† | n (%) | HR (95% CI)† | p-value‡ | |
| Total recreational physical activity | ||||||
| No activity | 22,807 (16) | 386 (16) | 1.0 (ref) | 54 (18) | 1.0 (ref) | 0.30 |
| 0.01 – 6.50 | 39,080 (27) | 693 (28) | 1.00 (0.87–1.15) | 75 (25) | 0.67 (0.46–0.99) | |
| 6.51 – 16.50 | 39,799 (28) | 726 (29) | 0.95 (0.83–1.09) | 86 (29) | 0.81 (0.55–1.18) | |
| ≥16.50 | 41,721 (29) | 686 (28) | 0.85 (0.74–0.98) | 81 (27) | 0.77 (0.51–1.13) | |
| Missing | 7,121 | 119 | 11 | |||
| ptrend | <0.01 | 0.47 | ||||
| Strenuous recreational physical activity§ | ||||||
| No activity | 107,778 (75) | 1,906 (73) | 1.0 (ref) | 215 (70) | 1.0 (ref) | 0.53 |
| 0.01 – 10.49 | 14,098 (10) | 209 (8) | 0.89 (0.76–1.05) | 36 (12) | 1.17 (0.77–1.78) | |
| ≥10.50 | 21,531 (15) | 376 (14) | 0.95 (0.84–1.07) | 45 (15) | 0.98 (0.68–1.44) | |
| Missing | 7,122 | 119 | 11 | |||
| ptrend | 0.25 | 0.91 | ||||
| Moderate and low-intensity recreational physical activity§ | ||||||
| No activity | 61,822 (43) | 1,096 (44) | 1.0 (ref) | 137 (46) | 1.0 (ref) | 0.53 |
| 0.01 – 5.74 | 40,642 (28) | 680 (27) | 0.90 (0.81–1.00) | 88 (30) | 0.83 (0.61–1.12) | |
| ≥5.75 | 40,943 (29) | 715 (29) | 0.88 (0.79–0.98) | 71 (24) | 0.75 (0.54–1.04) | |
| Missing | 7,122 | 119 | 11 | |||
| ptrend | 0.01 | 0.07 | ||||
*
ER+ = estrogen receptor-positive cases with known HER2 expression status; triple-negative = ER−/PR−/HER2−
†
Adjusted for age, education, income, family history of breast cancer, race, history of mammography (at baseline), mammography during follow-up, and BMI at baseline.
‡
Analysis of the partial likelihoods for equality between subtype-specific estimates.
§
Mutually-adjusted for strenuous-intensity and moderate/low-intensity activity.