Table 3.
Sedentary Time and Breast Cancer Incidence by Hormone Receptor Status (1995–2013) in the Black Women’s Health Study
| ER+ or PR+ | ER− and PR− | ER− and PR− and Her2− | |||||||
|---|---|---|---|---|---|---|---|---|---|
|
| |||||||||
| Cases/Person-years | Adjusteda HR (95% CI) |
P-trend | Cases/Person-years | Adjusteda HR (95% CI) |
P-trend | Cases/Person-years | Adjusteda HR (95% CI) |
P-trend | |
| Total sitting timec | 0.17 | 0.02 | 0.04 | ||||||
| <5 hours/day | 190/136,670 | Reference | 82/136,521 | Reference | 30/136,006 | Reference | |||
| 5–<7 hours/day | 371/275,055 | 1.00 (0.82, 1.23) | 162/272,534 | 1.21 (0.88, 1.68) | 59/271,588 | 1.05 (0.62, 1.78) | |||
| 7–<10 hours/day | 330/220,587 | 1.11 (0.90, 1.36) | 136/218,531 | 1.24 (0.88, 1.75) | 58/217,899 | 1.23 (0.72, 2.09) | |||
| ≥10 hours/day | 116/76,073 | 1.16 (0.88, 1.52) | 51/75,389 | 1.70 (1.13, 2.55) | 26/75,177 | 1.91 (1.04, 3.49) | |||
| Sitting at workc | 0.52 | 0.62 | 0.18 | ||||||
| <1 hour/day | 129/96,139 | Reference | 59/95,380 | Reference | 18/94,945 | Reference | |||
| 1–2 hours/day | 146/94,967 | 1.05 (0.79, 1.39) | 61/94,158 | 1.03 (0.65, 1.64) | 25/93,840 | 1.31 (0.61, 2.82) | |||
| 3–4 hours/day | 228/147,606 | 1.05 (0.81, 1.37) | 87/145,966 | 1.04 (0.68, 1.59) | 41/145,572 | 1.42 (0.70, 2.88) | |||
| ≥5 hours/day | 504/371,006 | 1.08 (0.85, 1.37) | 244/367,802 | 1.39 (0.96, 2.02) | 89/366,642 | 1.55 (0.81, 3.00) | |||
| Watching TVb,c | 0.53 | 0.20 | 0.18 | ||||||
| <1 hour/day | 69/57,775 | Reference | 36/57,305 | Reference | 14/57,111 | Reference | |||
| 1–2 hours/day | 352/256,624 | 0.92 (0.69, 1.23) | 145/254,233 | 1.09 (0.70, 1.70) | 56/253,410 | 1.42 (0.64, 3.16) | |||
| 3–4 hours/day | 406/271,850 | 1.03 (0.78, 1.38) | 167/269,414 | 1.03 (0.66, 1.61) | 64/268,501 | 1.32 (0.59, 2.94) | |||
| ≥5 hours/day | 181/123,881 | 0.99 (0.72, 1.36) | 85/122,779 | 1.38 (0.86, 2.23) | 39/122,384 | 1.89 (0.82, 4.36) | |||
Abbreviations: CI, confidence interval; ER−, estrogen receptor negative; ER+, estrogen receptor positive; HR, hazard ratio; Her2−, human epidermal growth factor 2 negative; PR−, progesterone receptor negative; PR+, progesterone receptor positive; TV, television.
Cox proportional hazards regression, with values updated using Anderson-Gill method, adjusted for: age (continuous), geographic region of residence (Northeast, South, Midwest, West, other), BMI (<25, 25–<30, 30–<35, ≥35 kg/m2), education (≤12, 13–15, ≥ 16 years), recreational physical activity (low, moderate, high), caloric intake (continuous), parity (0, 1–2, ≥3), age at menarche (≤11, 12–13, ≥14), menopausal hormone use (premenopausal, postmenopausal-never, postmenopausal-<5 years, postmenopausal- ≥ 5 years), oral contraceptive use (never, 0.5–5, ≥5 years), family history of breast cancer (yes/no), mammogram (ever, never), smoking (never, former, current-<15 per day, current-≥15 per day).
1995-Watching TV only, 1998-Watcing TV or videos, 1999 and 2001-Watching TV, videos, home computer.
Test for heterogeneity by subtype: Total time sitting, p=0.31; Sitting at work, p=0.10; Watching TV, p=0.81.