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Table 1 Characteristics (mean (SD), or number (percentage)) of patients (cases) and controls, by mode of detection (screen-detected or interval breast cancer)

From: Predicting interval and screen-detected breast cancers from mammographic density defined by different brightness thresholds

  Interval cancer Screen-detected cancer
Cases (n = 168)
Mean (SD)
Controls (n = 498)
Mean (SD)
P a Cases (n = 422)
Mean (SD)
Controls (n = 1197)
Mean (SD)
P a
Age at mammogram (years) 56.0 (6.8) 56.2 (6.8) 0.2 58.8 (7.5) 58.4 (7.6) 0.007
Body mass index (kg/m2) 26.7 (5.3) 26.5 (4.9) 0.8 27.3 (5.0) 26.5 (4.8) 0.002
Number of live births 2.6 (0.9) 2.7 (0.9) 0.2 2.8 (1.0) 2.7 (0.9) 0.96
  N (%) N (%) P N (%) N (%) P
Parity
 Yes 139 (83) 425 (85) 0.4 359 (85) 1046 (87) 0.3
 No 29 (17) 73 (15)   63 (15) 151 (13)  
Menopausal status
 Premenopausal 67 (40) 197 (40) 0.6 127 (30) 359 (30) 0.3
 Postmenopausal 101 (60) 301 (60)   295 (70) 838 (70)  
Breast feeding
 Yes 123 (73) 380 (76) 0.5 327 (77) 937 (78) 0.7
 No 41 (25) 110 (22)   88 (21) 240 (20)  
 Missing 4 (2) 8 (2)   7 (2) 20 (2)  
Family history of breast cancer
 Yes 44 (26) 75 (15) 0.001 91 (22) 165 (14) < 0.001
 No 124 (74) 423 (85)   331 (78) 1032 (86)  
Ever alcohol consumption
 Yes 119 (71) 318 (64) 0.08 248 (59) 759 (63) 0.2
 Never 49 (29) 180 (36)   174 (41) 438 (37)  
Ever use of oral contraceptive
 Yes 102 (61) 324 (65) 0.2 247 (59) 711 (59) 0.8
 Never 66 (39) 172 (35)   174 (41) 492 (40)  
 Missing 0 (0) 2 (0)   1 (0) 4 (1)  
Ever use of hormonal therapy
 Yes 54 (32) 141 (28) 0.3 134 (32) 333 (28) 0.1
 Never 113 (67) 355 (71)   284 (67) 859 (72)  
 Missing 1 (1) 2 (1)   4 (1) 5 (0)  
  1. SD standard deviation
  2. aP indicates the significance of differences between cases and matched controls based on conditional logistic regression