Skip to main content
letter
. 2014 Dec 4;112(3):567–571. doi: 10.1038/bjc.2014.600

Table 3. Association between baseline weekday sleep duration and breast cancer risk among women in the Breast Cancer Detection Demonstration Project, by hormonal receptor status of breast cancer.

  Weekday sleep duration, hour
  
Breast cancer subtype <6 6–<7 7–<8 8–<9 9+ P for trend
ER+
No. of cases/person-years 18/13 106 124/54 537 221/94 491 378/130 102 98/32 387  
Multivariate RRa (95% CI) 0.53 (0.33, 0.86) 0.83 (0.68, 1.02) 0.82 (0.69, 0.97) Ref 1.04 (0.83, 1.30) 0.001
ER−
No. of cases 14/13 106 25/54 537 55/94 491 73/130 102 21/32 387  
Multivariate RRa (95% CI) 2.12 (1.18, 3.82) 0.84 (0.53, 1.33) 1.02 (0.72, 1.45) Ref 1.17 (0.72, 1.91) 0.65
PR+
No. of cases/person-years 17/13 101 103/54 526 182/94 448 307/130 040 86/32 368  
Multivariate RRa (95% CI) 0.62 (0.38, 1.02) 0.85 (0.68, 1.07) 0.83 (0.69, 1.00) Ref 1.12 (0.88, 1.42) 0.003
PR−
No. of cases 14/13 101 42/54 526 82/94 448 128/130 040 28/32 368  
Multivariate RRa (95% CI) 1.21 (0.69, 2.12) 0.81 (0.57, 1.15) 0.89 (0.67, 1.18) Ref 0.89 (0.59, 1.35) 0.73
ER+PR+
No. of cases/person-years 14/13 101 98/54 519 171/94 438 292/130 024 80/32 357  
Multivariate RRa (95% CI) 0.54 (0.31, 0.93) 0.86 (0.68, 1.08) 0.82 (0.68, 1.00) Ref 1.10 (0.85, 1.41) 0.003
ER−PR−
No. of cases 11/13 101 18/54 519 43/94 438 58/130 024 17/32 357  
Multivariate RRa (95% CI) 2.07 (1.07, 4.02) 0.77 (0.45, 1.30) 1.03 (0.69, 1.52) Ref 1.19 (0.69, 2.04) 0.89

Abbreviations: CI=confidence interval; ER=oestrogen receptor; PR=progesterone receptor; RR=relative risk.

a

Adjusted for age (continuous), race (black, white, other), education (less than high school, high school graduate, some college, college or higher), marital status (married, unmarried), body-mass index (<18.5, 18.5 – 24.9, 25 – 29.9, 30+ kg m−2), vigorous physical activity (<1, 1 – <2, 2+ hours per day), smoking status (former, current, never smoker), pack-year (0, >0 – 20, >20 – 40, >40), year since quitting (never smoker, current smoker, 0.5 – 4, 5 – 9, 10+ years), age at first live birth (<20, 20 – 29, 30+ years), number of live birth (0, 1 – 2, 2+), age at menarche (12 or younger, older than 12), menopause (yes, no), use of hormonal replacement therapy (yes, no), use of multivitamin (yes, no), history of diabetes (yes, no), family history of cancer (no history, breast or ovarian cancer, other cancer) and alcohol consumption (never drinker, 0 – 6, 7 – 15, 16+ g per day).