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Table 1 Characteristics of study sample

From: Combining quantitative and qualitative breast density measures to assess breast cancer risk

  Invasive breast cancer cases (n = 1720) Matched control subjects (n = 3686)
Age, years, mean (SD) 59.5 (12.1) 59.6 (12.0)
Body mass index, kg/m2, mean (SD) 26.3 (5.7) 26.2 (5.7)
Dense breast volume,a ml, median (IQR) 57.8 (41.0–82.5) 50.7 (36.8–70.2)
Age at first live birth, n (%)
  < 30 years 856 (50.1%) 2085 (56.6%)
 None or ≥ 30 years 852 (49.9%) 1600 (43.4%)
Family history of breast cancer,b n (%)
 No 1218 (71.2%) 2991 (81.2%)
 Yes 493 (28.8%) 693 (18.8%)
History of breast biopsy, n (%)
 No 1304 (76.4%) 3040 (82.6%)
 Yes 402 (23.6%) 641 (17.4%)
Race/ethnicity, n (%)
 White 1380 (80.3%) 3012 (81.7%)
 Asian 218 (12.7%) 437 (11.9%)
 Black 34 (2.0%) 67 (1.8%)
 Hispanic 37 (2.2%) 101 (2.7%)
 Other 50 (2.9%) 69 (1.9%)
BI-RADS breast density,c n (%)
 Almost entirely fat (a) 233 (13.5%) 731 (19.8%)
 Scattered fibroglandular densities (b) 668 (38.8%) 1557 (42.2%)
 Heterogeneously dense (c) 600 (34.9%) 1115 (30.2%)
 Extremely dense (d) 219 (12.7%) 283 (7.7%)
  1. BI-RADS Breast Imaging Reporting and Data System
  2. Data are presented as number (percent) missing for cases and control subjects for age at first birth (13 [0.2%]), family history of breast cancer (11 [0.2%]), history of breast biopsy (19 [0.4%]), and race/ethnicity (3 [0.1%])
  3. aMeasured with Volpara software
  4. bMother, sister, or daughter with breast cancer
  5. cBI-RADS breast density: a = almost entirely fat, b = scattered fibroglandular densities, c = heterogeneously dense, d = extremely dense