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Table 4 Case-only odds ratios and 95% confidence intervals from logistic regression modelsa of associations between breast cancer tumor subtypes and demographic, reproductive, and lifestyle risk factors, combined LACE and Pathways Studies (n = 2544)

From: Epidemiology of breast cancer subtypes in two prospective cohort studies of breast cancer survivors

  Luminal A (comparison) Triple negativea HER2-overexpressinga
  n n OR 95% CI n OR 95% CI
Age at diagnosis (years)        
   ≥ 65 (Ref) 637 68 Ref --- 23 Ref ---
   50 to 64 871 115 1.99 0.85, 1.62 45 1.39 0.83, 2.32
   < 50 355 105 2.78 1.99, 3.90 25 1.75 0.97, 3.15
   Test for trend     P ≤ 0.0001    P = 0.03
Race/ethnicity        
   White (Ref) 1464 204 Ref --- 60 Ref ---
   African American 92 44 3.14 2.12, 4.66 5 1.25 0.49, 3.21
   Hispanic 135 21 0.93 0.57, 1.53 13 2.19 1.16, 4.13
   Asian 135 12 0.53 0.28, 0.97 12 2.02 1.05, 3.88
   Other 37 7 1.28 0.56, 2.94 3 1.95 0.58, 6.52
Menopausal status        
   Postmenopausal (Ref) 1283 163 Ref --- 57 Ref ---
   Premenopausal 406 91 0.84 0.55, 1.27 21 0.65 0.31, 1.33
Family history        
   No (Ref) 1453 229 Ref --- 80 Ref ---
   Yes 410 59 0.95 0.69, 1.29 13 0.62 0.34, 1.13
Age at first full-term pregnancy (years)        
   Nulliparous (Ref) 335 52 Ref --- 13 Ref ---
   < 26 959 163 1.28 0.90, 1.82 61 2.02 1.07, 3.80
   ≥ 26 567 72 0.93 0.63, 1.38 18 0.86 0.42, 1.79
Parity        
   Nulliparous (Ref) 335 52 Ref --- 13 Ref ---
   1 to 2 children 837 137 1.11 0.78, 1.58 40 1.30 0.68, 2.47
   ≥ 3 children 691 99 1.18 0.81, 1.72 40 1.82 0.94, 3.53
Lifetime duration of breastfeeding        
   Never (Ref) 871 148 Ref --- 43 Ref ---
   0 to 3 months 255 41 1.04 0.71, 1.52 16 1.29 0.71, 2.35
   ≥ 4 months 711 97 0.78 0.59, 1.03 32 0.86 0.54, 1.38
Parity among never breastfedb        
   Nulliparous (Ref) 321 50 Ref --- 12 Ref ---
   1 to 2 children 326 59 1.34 (0.87, 2.08) 15 1.52 (0.68, 3.41)
   ≥ 3 children 224 39 1.68 (1.00, 2.81) 16 3.03 (1.27, 7.23)
Parity among 0 to 3 months breastfedb        
   1 to 2 children (Ref) 144 25 Ref --- 9 Ref ---
   ≥ 3 children 108 16 1.16 (0.53, 2.56) 7 1.82 (0.57, 5.80)
Parity among ≥ 4 months breastfedb        
   1 to 2 children (Ref) 358 52 Ref --- 14 Ref ---
   ≥ 3 children 352 44 0.99 (0.63, 1.55) 17 1.23 (0.57, 2.66)
Alcohol use        
   Never (Ref) 709 110 Ref --- 39 Ref ---
   Ever 880 129 0.98 0.73, 1.30 40 0.94 0.59, 1.50
Smoking history        
   Never (Ref) 921 146 Ref --- 51 Ref ---
   ≤ 10 251 41 0.95 0.65, 1.40 7 0.51 0.23, 1.14
   11 to 19 147 21 0.89 0.54, 1.47 8 1.17 0.54, 2.56
   ≥ 20 531 78 0.98 0.72, 1.34 26 1.05 0.63, 1.73
Hormone replacement therapy (postmenopausal only)        
   Never (Ref) 314 50 Ref --- 24 Ref ---
   Ever 943 112 0.83 0.57, 1.20 33 0.45 0.26, 0.79
Oral contraceptive use        
   Never (Ref) 647 80 Ref --- 29 Ref ---
   Ever 1160 202 0.97 0.72, 1.31 63 1.12 0.69, 1.83
BMI (kg/m2)c        
   < 25 (Ref) 785 110 Ref --- 39 Ref ---
   25 to 29 563 99 1.33 0.98, 1.81 31 1.21 0.74, 1.99
   ≥ 30 500 77 1.04 0.75, 1.45 23 1.03 0.59, 1.78
BMI (kg/m2) among premenopausalb        
   < 25 (Ref) 223 39 Ref --- 7 Ref ---
   25 to 29 99 28 1.82 1.03, 3.24 7 2.15 0.70, 6.58
   ≥ 30 81 23 1.97 1.03, 3.77 7 2.51 0.74, 8.51
BMI (kg/m2) among postmenopausalb        
   < 25 (Ref) 480 59 Ref --- 25 Ref ---
   25 to 29 422 60 1.08 0.73, 1.59 18 0.86 0.46, 1.61
   ≥ 30 372 43 0.76 0.49, 1.17 14 0.76 0.38, 1.51
  1. a Adjusted for age at diagnosis, race/ethnicity, and Pathways/LACE study origin except in models with age at diagnosis or race/ethnicity as main predictors.
  2. b P for interaction not statistically significant (P > 0.05) in any tumor subtype model.
  3. c BMI, body mass index one year pre-diagnosis (LACE) and around diagnosis (Pathways).
  4. CI = confidence interval; HER2 = human epidermal growth receptor 2; OR = odds ratio.