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Table 2 Summary characteristics of study population by breast cancer case status

From: High-throughput mammographic-density measurement: a tool for risk prediction of breast cancer

Characteristic Cases (n= 1,498) Controls (n= 1,495) P
Median    
   Percentage density (%) 16.9 11.0 <0.001
   Absolute dense area (cm2) 24.3 16.9 <0.001
Mean (SD)    
   Age at diagnosis or reference date (y) 61.2 (7.1) 62.8 (6.9) <0.001
   Age at mammogram (y) 60.6 (7.2) 62.8 (6.7) <0.001
   Age at menarche (y) 13.5 (1.4) 13.6 (1.4) 0.084
   Age at menopause (y) 50.6 (3.8) 50.0 (3.9) 0.001
   BMI at diagnosis or reference date (kg/m2) 25.1 (3.6) 25.2 (3.9) 0.801
   Alcohol consumption (g/day) 2.8 (5.0) 2.3 (4.2) 0.008
   Percentage density (%) 20.7 (16.1) 15.7 (14.5) <0.001
   Absolute dense area (cm2) 30.2 (23.7) 23.3 (21.5) <0.001
Frequency, number (%)    
   Categoric percentage density (%)    <0.001
   <10 477 (31.8) 680 (45.5)  
   10-24 538 (35.9) 506 (33.8)  
   25-49 384 (25.6) 250 (16.7)  
   50-74 96 (6.4) 57 (3.8)  
   ≥75 3 (0.2) 2 (0.1)  
   Categoric absolute dense area (cm2)    <0.001
   <10 288 (19.2) 475 (31.8)  
   10-24 471 (31.4) 509 (34.0)  
   25-49 460 (30.7) 347 (23.2)  
   50-74 211 (14.1) 114 (7.6)  
   75-99 47 (3.1) 39 (2.6)  
   ≥100 21 (1.4) 11(0.7)  
   Parity and age at first birth    <0.001
   Nulliparous 190 (12.7) 148 (9.9)  
   1-3 children, age at first birth <25 y 556 (37.1) 555 (37.1)  
   1-3 children, age at first birth 25-29 y 420 (28.0) 399 (26.7)  
   1-3 children, age at first birth ≥30 y 223 (14.9) 212 (14.2)  
   ≥4 children, age at first birth <25 y 29 (1.9) 31 (2.1)  
   ≥4 children, age at first birth ≥25 y 78 (5.2) 150 (10.0)  
   Hormone replacement therapy    <0.001
   Never used hormones 722 (48.2) 844 (56.5)  
   Ever used hormones 774 (51.7) 649 (43.4)  
   Unknown status of hormone use 2 (0.1) 2 (0.1)  
   Family history of breast cancer (ever) 207 (13.8) 119 (8.0) <0.001
   Benign breast disease (ever) 351 (23.4) 141 (9.4) <0.001