Table 1 Characteristics of cases and controls according to menopausal statusa
From: Mammographic density and the risk of breast cancer in Japanese women
Premenopausal women | Postmenopausal women | |||
|---|---|---|---|---|
Variables | Cases, n =71 | Controls, n =370 | Cases, n=75 | Controls, n =289 |
Age (years) | 43.1±6.2 | 42.7±5.9 | 62.2±9.1 | 58.1±6.3 |
BMI (kg m−2) | 22.0±2.5 | 21.8±2.9 | 23.9±2.9 | 23.2±3.2 |
Education (years) | 13.2±2.1 | 12.7±1.8 | 11.0±2.1 | 11.4±1.9 |
Age at menarch (years) | 12.7±1.2 | 12.8±1.3 | 14.5±3.5 | 14.1±1.7 |
Age at first birth (years) | 26.5±3.6 | 25.3±2.7 | 24.8±3.0 | 25.0±3.2 |
Age at menopause (years) | — | — | 48.6±4.2 | 49.2±4.1 |
Number of parity | 1.6±1.1 | 2.2±0.8 | 2.0±0.9 | 2.3±0.8 |
Alcohol intake (ml day−1) | 7.7±17.1 | 6.8±18.2 | 5.3±12.1 | 4.8±13.0 |
Exercise (METs·h week−1) | 6.3±6.2 | 4.5±5.8 | 4.5±7.4 | 4.3±7.1 |
Current smokers (%) | 15.5 | 9.0 | 5.5 | 4.0 |
Ex-smokers (%) | 4.2 | 5.5 | 4.1 | 3.3 |
Current use of HRT (%) | 5.9 | 3.0 | 2.7 | 2.6 |
Past use of HRT (%) | 7.4 | 8.3 | 9.5 | 7.7 |
Family historyb (%) | 9.9 | 4.3 | 8.0 | 3.8 |
Breast feeding (%) | 73.2 | 90.7 | 90.0 | 90.4 |
