Table 2:
Risk of breast cancer associated with self-reported sleep duration, MEC 1993–2013
| Sleep Duration | ||||
|---|---|---|---|---|
| Group | ≤6 hr | 7–8 hr | ≥9 hr | p-interaction2 |
| HR (95%CI)1 | HR (95%CI) | HR (95%CI)1 | ||
| Overall3 | 1.03 (0.97–1.09) | 1.00 | 1.05 (0.95–1.15) | 0.45 |
| Ethnicity3 | 0.61 | |||
| White | 1.04 (0.92–1.18) | 1.00 | 0.93 (0.79–1.23) | |
| African American | 0.95 (0.83–1.09) | 1.00 | 0.99 (0.78–1.22) | |
| Native Hawaiian | 1.03 (0.87–1.23) | 1.00 | 1.01 (0.76–1.36) | |
| Japanese American | 1.04 (0.94–1.14) | 1.00 | 1.16 (0.93–1.43) | |
| Latina | 1.08 (0.93–1.26) | 1.00 | 1.20 (0.97–1.50) | |
| Age (%)3 | 0.64 | |||
| <55 years | 1.08 (0.99–1.19) | 1.00 | 1.10 (0.93–1.29) | |
| 55–64 years | 1.10 (1.00–1.21) | 1.00 | 1.07 (0.91–1.26) | |
| 65+ years | 0.88 (0.79–0.99) | 1.00 | 0.95 (0.80–1.14) | |
| BMI (kg/m2)3 | 0.45 | |||
| Underweight | 1.25 (0.83–1.90) | 1.00 | 1.48 (0.74–2.98) | |
| Normal | 1.06 (0.97–1.15) | 1.00 | 1.06 (0.91–1.24) | |
| Overweight | 1.00 (0.91–1.10) | 1.00 | 0.96 (0.81–1.13) | |
| Obese | 1.04 (0.92–1.17) | 1.00 | 1.15 (0.96–1.38) | |
| ER and PR status4 | 0.23 | |||
| ER+PR+5 | 1.07 (0.99–1.16) | 1.00 | 1.04 (0.91–1.19) | |
| ER−PR−6 | 1.06 (0.90–1.24) | 1.00 | 0.93 (0.70–1.22) | |
| Discordant7 | 1.03 (0.86–1.22) | 1.00 | 1.29 (0.98–1.70) | |
HRs (Hazard Ratios) obtained from Cox regression adjusted for BMI, ethnicity, age, education, family history of breast cancer, smoking status, alcohol use, physical activity, age at menarche, age at first live birth, number of children, hormone treatment, menopausal status, caffeine intake, and total energy intake
p-interaction is based on Wald statistic for cross-product interaction terms
Corresponding number of participants per group are found in Table 1
4426 breast cancer cases who had a specific ER and PR type
Positive ER (estrogen receptor) and PR (progesterone receptor) breast cancer status; based on 3056 participants (≤6 hr=1075; 7–8hr=1734; ≥9hr=247)
Negative ER and PR breast cancer status; based on 738 participants (≤6 hr=262; 7–8hr=419; ≥9hr=75)
Positive ER and negative PR, or negative ER and positive PR breast cancer status; based on 632 participants (≤6 hr=216; 7–8hr=355; ≥9hr=61)