Table 1.

Baseline characteristics of 357 postmenopausal breast cancer case patients and 533 matched control subjects (in 2000)

CharacteristicCase patients (n = 357)Control subjects (n = 533)
Mean age, y (SD)67.2 (6.7)67.2 (6.7)
Mean age at menarche, y (SD)12.6 (1.4)12.6 (1.4)
Mean age at menopause*, y (SD)48.4 (6.0)47.5 (6.5)
Mean No. of births (SD)3.2 (1.4)3.2 (1.6)
Family history of breast cancer, %23.816.1
Mean BMI, kg/m2 (SD)26.9 (5.0)26.4 (5.0)
Mean amount of alcohol consumed/day, gm (SD)6.3 (9.8)5.4 (9.1)
Current smoker, %5.64.1
History of benign breast disease, %64.260.6
Current antidepressant use, %12.413.1
Postmenopausal hormones ever used, %67.258.9
First morning urine, %95.894.6
Frequently difficulty sleeping, %10.811.3
Frequently snores, %21.118.5
Average. hours of sleep/day 5 or less h, %6.83.0
Mean aMT6s level, ng/mg creatinine (SD)24.5 (29)28.8 (39)
Mean creatinine level, mmol/L (SD)6.1 (3.8)5.5 (3.4)
  • Abbreviation: BMI, body mass index.

  • * Natural menopause or menopause due to bilateral oophorectomy.

  • Among parous women only.