Table 1 Characteristics of mammographic measures and covariates of the monozygotic twins
From: Causal relationships between breast cancer risk factors based on mammographic features
Continuous variables | Mean | Median | 25% percentile | 75% percentile |
|---|---|---|---|---|
Cumulus (cm2) | 33.15 | 29.14 | 18.03 | 42.68 |
Altocumulus (cm2) | 12.37 | 11.18 | 6.79 | 16.10 |
Brightest areas (Cirrocumulus) (cm2) | 2.32 | 1.62 | 0.75 | 3.12 |
Light areas (cm2) | 20.79 | 17.40 | 10.54 | 26.79 |
Bright areas (cm2) | 10.04 | 8.91 | 5.81 | 13.31 |
Cirrus | 2910.32 | 2910.40 | 2910.02 | 2910.75 |
BMI at mammograms (kg/m2) | 25.42 | 24.66 | 22.21 | 27.71 |
Age at mammograms (years) | 53.88 | 53.14 | 47.45 | 59.26 |
Difference between age at mammography and age at survey (years) | 1.68 | 0.23 |  − 0.43 | 2.47 |
Categorical variables | N (%) |
|---|---|
Menopausal status | Â |
Premenopausal | 282 (38%) |
Postmenopausal | 460 (62%) |
Pregnant | Â |
Never | 85 (11%) |
Ever | 657 (89%) |
Benign breast disease | Â |
Never | 515 (69%) |
Ever | 227 (31%) |
Breastfeeding | Â |
Never | 163 (22%) |
Ever | 579 (78%) |
Number of live births | Â |
0 | 102 (14%) |
1 | 57 (8%) |
2 | 260 (35%) |
3 | 206 (28%) |
4 | 88 (12%) |
≥5 | 29 (4%) |
Number of relatives diagnosed with breast cancer | Â |
0 | 494 (67%) |
1 | 193 (26%) |
2 | 52 (7%) |
3 | 3 (0%) |
Age at menarche (years) | Â |
 < 12 | 105 (14%) |
≥12 and < 15 | 508 (69%) |
≥15 | 129 (17%) |