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Table 1 Population characteristics by tumor subtype, basal-like and luminal A breast cancers

From: Association between mammographic density and basal-like and luminal A breast cancer subtypes

Variable Overall cases versus controls Cases
Cases Controls Basal-like OR (95% CI) Luminal A OR (95% CI)
Subjects, number 491 528 48   181  
Age (CBCS), mean (range), ya 53.2 (28 to 74) 54.0 (31 to 74) 50.2 (33 to 73) 0.99 (0.96, 1.02) 54.5 (31, 74) 1.04 (1.02, 1.06)
BMI, mean (95% CI) 28.6 (15.1, 60.6) 28.8 (14.6, 60.9) 30.9 (19.1 to 44.2) 1.06 (1.02, 1.10) 28.5 (15.0, 52.6) 1.00 (0.98, 1.03)
Number of days, mean (95% CI)b −21 (−1401, 365) 149 (−1617, 1095) −27 (−938, 365) −10 (−1050, 365)
Race, n (%)       
 White 297 (60.5%) 324 (61.4%) 21 (43.8%) 1.00 116 (64.1%) 1.00
 African American 194 (39.5%) 204 (38.6%) 27 (56.3%) 3.32 (1.80, 6.12) 65 (35.9%) 1.31 (0.90, 1.89)
Menopausal status, n (%)       
 Premenopausal 200 (40.7%) 213 (40.3%) 25 (52.1%) 1.00 67 (37.0%) 1.00
 Postmenopausal 291 (59.3%) 315 (59.7%) 23 (47.9%) 0.90 (0.49, 1.65) 114 (63.0%) 1.83 (1.27, 2.65)
Family history, n (%)c       
 No 386 (81.1%) 440 (85.6%) 39 (83.0%) 1.00 149 (84.2%) 1.00
 Yes 90 (18.9%) 74 (14.4%) 8 (17.0%) 1.24 (0.55-2.82) 28 (15.8%) 1.11 (0.67-1.84)
 Missing 15 14 1   4  
Age at menarche, n (%)       
 <13 y 257 (52.3%) 230 (43.6%) 32 (66.7%) 1.00 92 (50.8%) 1.00
 ≥13 y 234 (47.7%) 298 (56.4%) 16 (33.3%) 0.37 (0.19-0.70) 89 (49.2%) 0.76 (0.53-1.09)
Parity and age at FFTP       
 Nulliparous 74 (15.1%) 67 (12.7%) 6 (12.5%) 1.00 31 (17.1%) 1.00
 Parous, <26 y 312 (63.5%) 347 (65.7%) 36 (75.0%) 2.07 (1.04-4.15) 107 (59.1%) 0.93 (0.64-1.34)
 Parous, 26+y 105 (21.4%) 114 (21.6%) 6 (12.5%) 0.43 (0.18-1.06) 43 (23.8%) 0.96 (0.63-1.47)
Breastfeeding, n (%)       
 Never 299 (60.9%) 324 (61.4%) 32 (66.7%) 1.00 110 (60.8%) 1.00
 Ever 192 (39.1%) 204 (38.6%) 16 (33.3%) 0.84 (0.44-1.60) 71 (39.2%) 1.09 (0.75-1.57)
Lifetime duration lactation, n (%)       
 Never 299 (60.9%) 324 (61.4%) 32 (66.7%) 1.00 110 (60.8%) 1.00
 >0-3 months 72 (14.7%) 69 (13.1%) 9 (18.8%) 1.71 (0.77-3.79) 26 (14.4%) 1.14 (0.68-1.92)
 4+ months 120 (24.4%) 135 (25.6%) 7 (14.6%) 0.50 (0.22-1.16) 45 (24.9%) 1.02 (0.67-1.55)
Current HT use, n (%)d       
 Yes 129 (26.4%) 181 (35.0%) 9 (18.8%) 1.00 43 (23.9%) 1.00
 No 359 (73.6%) 336 (65.0%) 39 (81.2%) 2.36 (1.11-5.05) 137 (76.1%) 1.84 (1.23-2.77)
 Missing 3 11 0   1  
Oral contraceptive use, n (%)       
 Never 170 (34.6%) 170 (32.4%) 11 (22.9%) 1.00 72 (39.8%) 1.00
 Ever 321 (65.4%) 355 (67.6%) 37 (77.1%) 1.21 (0.59-2.46) 109 (60.2%) 0.49 (0.34-0.71)
 Missing 0 3 0   0  
WHR, n (%)       
 <0.77 132 (27.3%) 169 (32.3%) 4 (8.7%) 1.00 45 (25.4%) 1.00
 0.77 to 0.83 171 (35.3%) 173 (33.0%) 17 (37.0%) 1.19 (0.63-2.24) 69 (39.0%) 1.41 (0.97-2.05)
 ≥0.84 181 (37.4%) 182 (34.7%) 25 (54.3%) 2.40 (1.30-4.42) 63 (35.6%) 1.17 (0.80-1.71)
 Missing 7 4 2   4  
  1. aMean age at diagnosis for cases and selection for controls in the CBCS; bmean number of days between diagnosis date for cases and selection date for controls in the CBCS, and the date of the mammogram chosen to assess mammographic density; cfirst-degree family history of breast cancer; dcurrent hormone therapy use at the time of the mammogram. OR, odds ratio; CBCS, Carolina Breast Cancer Study; BMI, body mass index; FFTP, first full-term pregnancy; HT, hormone therapy; WHR, waist-to-hip ratio; n, number of subjects.