Table 2.

Age-standardized characteristics by RTL quartiles among all subjects

CharacterisicQuartile 1Quartile 2Quartile 3Quartile 4P
Age (mean)59.258.758.057.7<0.01
Packyears (ever smokers)24.322.222.023.40.27
Packyears (past smokers)19.316.216.917.00.09
Cigarettes/d (ever smokers)*2.782.782.722.670.21
Cigarettes/d (past smokers)*2.782.712.642.590.12
PMH duration (y)4.283.634.033.510.07
BMI (kg/m2)25.325.625.325.50.33
Weight gain since age 18 y (kg)11.311.411.211.50.49
Age at menarche (y)12.512.512.612.60.57
Age at first birth (y)25.125.425.325.30.40
Parity3.102.993.023.020.59
Age at menopause (y)49.749.949.649.60.37
Family history of breast cancer (%)201823220.17
History of benign breast disease (%)605858580.85
Estrone (pg/mL)27.427.727.124.30.02
Estradiol (pg/mL)7.477.756.726.760.02
Estrone sulfate (pg/mL)2412372322100.09
  • Abbreviation: PMH, postmenopausal hormone.

  • * Cigarettes/d were recorded in categories of 1:1-4, 2:5-14, 3:15-24, 4:25-34, 5:35-44, 6: ≥45 cigarettes/d.