Table 1 Selected characteristics of breast cancer cases and controls
Variable | Cases n = 500 | Controls n = 500 |
|---|---|---|
Mean ± standard deviation | ||
Age at baseline (years) | 61.9 ± 6.0 | 61.9 ± 6.0 |
Age at menarche (years) | 12.7 ± 1.4 | 12.6 ± 1.4 |
Age at menopause (years) | 48.5 ± 6.4 | 48.1 ± 6.0 |
Paritya | 3.0 ± 1.2 | 3.3 ± 1.5 |
Race | Percentage | |
White | 98.6 | 98.8 |
Other or missing | 1.4 | 1.2 |
History of breast cyst | 38.8 | 30.0 |
Family history of breast cancer | 20.2 | 15.0 |
Ever pregnant | 88.8 | 90.0 |