Table 2 Age-adjusted (< 55, 55-59, 60-64, 65+ years) characteristics at postmenopausal mammography among 1,662 control women without breast cancer according to quintiles of absolute dense area, absolute non-dense area, and percent dense area
| Â | Quintiles of absolute dense area in cm2 | ||||
|---|---|---|---|---|---|
Characteristics | 1 (< 14.4) | 2 (< 26.6) | 3 (< 39.8) | 4 (< 64.3) | 5 (< 302.6) |
Number of controls | 333 | 332 | 333 | 332 | 332 |
Age at mammography, years | 62.2 | 61.4 | 62.0 | 60.6 | 60.4 |
Age at menopause, years | 49.2 | 49.5 | 49.8 | 49.0 | 49.0 |
Age at menarche, years | 12.6 | 12.7 | 12.6 | 12.6 | 12.6 |
Family history of breast cancer, % | 11.6 | 12.0 | 14.0 | 13.0 | 13.2 |
Nulliparous at the time of mammography, % | 4.0 | 5.5 | 5.2 | 8.0 | 10.2 |
Number of children at mammography1 | 3.6 | 3.6 | 3.4 | 3.2 | 3.2 |
Age at first child, years1 | 25.1 | 25.1 | 25.2 | 25.4 | 25.4 |
Body mass index at mammography, kg/m2 | 28.2 | 26.2 | 25.4 | 25.1 | 25.5 |
Alcohol use at mammography, g/day | 5.9 | 5.7 | 4.7 | 5.9 | 4.9 |
Current hormonal use, % | 30.3 | 34.6 | 34.8 | 42.4 | 56.1 |
Total area on mammogram, cm2 | 169 | 169 | 182 | 216 | 268 |
Absolute non-dense area on mammogram, cm2 | 162 | 148 | 149 | 164 | 171 |
| Â | Quintiles of absolute non-dense area in cm2 | ||||
Characteristics | 1 (< 76.2) | 2 (< 115.6) | 3 (< 163.9) | 4 (< 231.4) | 5 (< 538.8) |
Number of controls | 333 | 332 | 333 | 332 | 332 |
Age at mammography, years | 60.7 | 60.4 | 61.6 | 62.1 | 61.9 |
Age at menopause, years | 49.6 | 49.5 | 49.2 | 49.2 | 48.9 |
Age at menarche, years | 12.8 | 12.6 | 12.6 | 12.5 | 12.4 |
Family history of breast cancer, % | 12.1 | 14.2 | 11.8 | 13.0 | 12.6 |
Nulliparous at the time of mammography, % | 8.3 | 8.4 | 5.3 | 5.1 | 6.4 |
Number of children at mammography1 | 3.4 | 3.5 | 3.4 | 3.4 | 3.3 |
Age at first child, years1 | 25.5 | 25.4 | 25.2 | 25.2 | 24.9 |
Body mass index at mammography, kg/m2 | 22.4 | 24.7 | 25.9 | 27.5 | 30.1 |
Alcohol use at mammography, g/day | 6.9 | 6.0 | 5.6 | 5.2 | 3.2 |
Current hormonal use, % | 47.6 | 39.9 | 33.8 | 38.6 | 36.1 |
Total area on mammogram, cm2 | 93 | 135 | 179 | 241 | 355 |
Absolute dense area on mammogram, cm2 | 41 | 39 | 40 | 45 | 46 |
| Â | Quintiles of percent dense area | ||||
Characteristics | 1 (< 8.1) | 2 (< 15.7) | 3 (< 24.1) | 4 (< 37.1) | 5 (< 86.5) |
Number of controls | 334 | 331 | 333 | 332 | 332 |
Age at mammography, years | 62.2 | 62.0 | 61.8 | 60.8 | 59.7 |
Age at menopause, years | 49.1 | 49.7 | 49.3 | 49.1 | 49.0 |
Age at menarche, years | 12.6 | 12.5 | 12.5 | 12.7 | 12.8 |
Family history of breast cancer, % | 10.7 | 14.3 | 12.0 | 12.8 | 13.9 |
Nulliparous at the time of mammography, % | 6.2 | 2.7 | 5.5 | 8.0 | 11.4 |
Number of children at mammography1 | 3.6 | 3.5 | 3.4 | 3.2 | 3.1 |
Age at first child, years1 | 25.2 | 24.8 | 25.1 | 25.4 | 25.8 |
Body mass index at mammography, kg/m2 | 29.9 | 26.9 | 25.7 | 24.4 | 23.4 |
Alcohol use at mammography, g/day | 5.2 | 4.3 | 5.4 | 6.0 | 6.1 |
Current hormonal use, % | 27.1 | 32.7 | 36.4 | 47.3 | 54.1 |
Total area on mammogram, cm2 | 231 | 223 | 210 | 182 | 154 |
Absolute dense area on mammogram, cm2 | 10 | 27 | 41 | 55 | 76 |
Non-dense breast area on mammogram, cm2 | 221 | 196 | 169 | 127 | 78 |