Table 2

Characteristics of cases and controls by cohort participation

19741989
% cases (N = 235)% controls (N = 235)% cases (N = 105)% controls (N = 105)
Age at donation
 ≤4020.920.43.82.9
 41–5023.826.021.022.9
 51–6033.631.918.115.2
 ≥6121.721.757.159.1
Education
 <12 years38.343.024.831.4
 ≥12 years61.757.075.268.6
Family history of breast cancer
(define: mother, sister, grandmother)
 No79.291.173.387.6
 Yes20.98.926.712.4
Age at first birth
 <2018.719.222.922.9
 20–2940.435.751.449.5
 ≥306.84.31.03.8
 Nulliparous11.910.213.39.5
 Missing22.130.611.414.3
Age at menarche
 <1213.214.519.114.3
 12–1340.431.954.349.5
 ≥1417.517.916.222.9
 Missing28.935.710.513.3
Lactation (months)
 None51.940.061.947.6
 1–1216.614.919.120.0
 >126.09.85.717.1
 Missing25.535.313.315.2
Hormone replacement therapy
 Never58.348.565.754.3
 Ever16.614.920.024.8
 Missing25.136.614.321.0
Alcohol consumption
(no. of drinks/week)
 Never48.146.847.650.5
 <112.88.117.112.4
 1–37.78.114.315.2
 ≥413.27.214.37.6
 Missing18.329.86.714.3
Cigarette smoking (at donation)
 Never60.057.564.863.8
 Former16.615.723.821.0
 Current23.426.811.415.2
Time to diagnosis
 <248.6
 3–5 years12.3NA a51.4NA
 6–1017.9
 11–1528.5
 ≥1641.3
Estrogen receptor status
 ER-negative11.5NA19.0NA
 ER-positive33.266.7
 Unknown55.314.3
  • a NA, not applicable; ER, estrogen receptor.