TABLE I.
Baseline Characteristics of positive (Cancer) and negative (Cancer-Free) Cases in Our Dataset of 335 Cases.
| Risk factor | Category | Positive | Negative | P-value from t-test |
|---|---|---|---|---|
| Age, years | Mean ± SD | 60.2±10.6 | 51.2± 7.4 | < 0.01 |
| Density BIRADS, unadjusted | 0.01 a | |||
| Almost all fatty tissue | 7 (4.4%) | 6 (3.4%) | ||
| Scattered fibro-glandular densities | 64 (40.3%) | 50 (28.4%) | ||
| Heterogeneously dense | 83 (52.2%) | 107 (60.8%) | ||
| Extremely dense | 5 (3.1%) | 13 (7.4%) | ||
| Family history | 0.20 | |||
| No family history known | 83 (52.2%) | 84 (47.7%) | ||
| Cancers in the 1st degree relatives | 39 (24.5%) | 43 (24.4%) | ||
| Cancers in the 2nd degree relatives | 34 (21.4%) | 39 (22.2%) | ||
| Cancers in the 3rd degree relatives | 3 (1.9%) | 10 (5.7%) | ||
| Age at menarche, years | 0.89 | |||
| < 12 | 26 (16.4%) | 27 (15.6%) | ||
| 12 to 13 | 104 (65.4%) | 106 (61.3%) | ||
| ≥ 14 | 29 (18.2%) | 40 (23.1%) | ||
| Missing b | 0 | 3 | ||
| Parous | 128 (80.5%) | 128 (72.7%) | 0.09 | |
| Age at first birth, years | 0.41 | |||
| < 30 | 91 (57.2%) | 80 (45.5%) | ||
| ≥ 30 or nulliparous | 68 (42.8%) | 96 (54.5 %) | ||
| Menopausal status | < 0.01 | |||
| Premenopausal | 35 (22.0%) | 99 (56.3%) | ||
| Postmenopausal, natural | 118 (74.2%) | 71 (40.3%) | ||
| Postmenopausal, surgical | 3 (1.9%) | 4 (2.3%) | ||
| Postmenopausal, unknown | 3 (1.9%) | 2 (1.1%) |
a
Age-adjustment attenuated the difference in density BIRADS ratings between the cancer and “cancer-free” groups (age-adjusted P-value: ±1 year = 0.75; ±3 years = 0.31).
b
Missing values were omitted from the percentage calculations.