Table 1.
Baseline characteristics between breast cancer cases and their matched cancer-free controls *
| variable label | Overall N=2712 | Controls (N=2260) | Cases (N=452) | P-value |
|---|---|---|---|---|
| Age at baseline | 70.5 ± 4.4 | 70.5 ± 4.4 | 70.5 ± 4.4 | 1.0000 |
| Body mass index (kg/m2) (mean, std) | 26.5 ± 4.5 | 26.4 ± 4.4 | 27.1 ± 4.9 | 0.001 |
| Waist circumference (cm) (mean, std) | 83.3 ± 11.0 | 83.1 ± 11.0 | 84.5 ± 11.3 | 0.02 |
| Education | 0.01 | |||
| <12 years | 619 (22.8%) | 524 (23.2%) | 95 (21.0%) | |
| 12 years | 1133 (41.8%) | 953 (42.2%) | 180 (39.8%) | |
| 13–16 years | 719 (26.5%) | 600 (26.5%) | 119 (26.3%) | |
| 17 or more | 241 (8.9%) | 183 (8.1%) | 58 (12.8%) | |
| Smoke packyear | 0.02 | |||
| Never smoker | 1620 (59.7%) | 1327 (58.7%) | 293 (64.8%) | |
| <10 | 330 (12.2%) | 285 (12.6%) | 45 (10.0%) | |
| 10–<30 | 351 (12.9%) | 302 (13.4%) | 49 (10.8%) | |
| 30–<50 | 251 (9.3%) | 203 (9.0%) | 48 (10.6%) | |
| ≥ 50 | 160 (5.9%) | 143 (6.3%) | 17 (3.8%) | |
| Total kcal/wk expended in past year | 1645 ± 1645 | 1628 ± 1644 | 1729 ± 1648 | 0.23 |
| Total # alcoholic drinks over lifetime | 5157 ± 12472 | 5151 ± 12967 | 5187 ± 9635 | 0.96 |
| Hypertension | 0.58 | |||
| 0 | 1751 (64.6%) | 1454 (64.3%) | 297 (65.7%) | |
| 1 | 961 (35.4%) | 806 (35.7%) | 155 (34.3%) | |
| Diabetes | 0.66 | |||
| 0 | 2550 (94.0%) | 2127 (94.1%) | 423 (93.6%) | |
| 1 | 162 (6.0%) | 133 (5.9%) | 29 (6.4%) | |
| Objectively measured physical function | ||||
| Grip strength (kilograms) | ||||
| Average grip strength | 21.3 ± 4.3 | 21.3 ± 4.4 | 21.5 ± 4.1 | 0.34 |
| Max grip strength | 22.6 ± 4.4 | 22.6 ± 4.4 | 22.8 ± 4.1 | 0.30 |
| Timed chair stand (seconds) | 12.1 ± 4.3 | 12.1 ± 4.4 | 12.0 ± 4.0 | 0.72 |
| Gait speed/stride length | ||||
| Regular gait speed (meters per second) | 1.0 ± 0.2 | 1.0 ± 0.2 | 1.0 ± 0.2 | 0.17 |
| Rapid gait speed (meters per second) ** | 1.3 ± 0.3 | 1.3 ± 0.3 | 1.3 ± 0.3 | 0.21 |
| Regular stride length (meters) | 0.6 ± 0.1 | 0.6 ± 0.1 | 0.6 ± 0.1 | 0.10 |
| Rapid stride length (meters) ** | 0.6 ± 0.1 | 0.6 ± 0.1 | 0.6 ± 0.1 | 0.81 |
| Quadriceps strength (pounds) ** | ||||
| Average quadriceps strength | 64.0 ± 27.0 | 63.7 ± 26.7 | 65.2 ± 28.1 | 0.33 |
| Peak quadriceps strength | 60.1 ± 25.8 | 59.9 ± 25.7 | 61.5 ± 26.5 | 0.27 |
| Cancer stage | ||||
| I | 290 (64.2%) | |||
| II | 56 (12.4%) | |||
| III | 59 (13.1%) | |||
| IV | 17 (3.8%) | |||
| Unknown | 30 (6.6%) |
*:
Values expressed as n (%), mean ± standard deviation. P-value comparisons across breast categories are based on Chi-square test for categorical variables; T test for continuous variables.
**
These physical functions were not measured at baseline. They were based on measurements at visit 2.