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Table 1 Baseline characteristics of study cohort according to tertiles of serum 25(OH)D (n = 1,295)

From: Serum 25-hydroxyvitamin D and postmenopausal breast cancer survival: a prospective patient cohort study

  Serum 25(OH)D
Characteristic < 35 nmol/L 35-55 nmol/L ≥ 55 nmol/L
Number of patients 432 407 456
Age at diagnosis (years), mean ± SD 64.0 ± 5.7 63.7 ± 5.4 62.5 ± 5.4
25(OH)D concentration (nmol/L), median 25.7 44.4 71.3
Follow-up time (years), median 5.6 5.9 6.0
Time between diagnosis and blood collection (days), median 82 63 130
BMI at recruitment (kg/m2), mean ± SD 27.7 ± 4.9 26.6 ± 4.4 25.5 ± 4.1
Leisure time physical activity since age 50 (met-hr/wk), mean ± SD 37.3 ± 30.0 43.5 ± 33.0 49.5 ± 36.4
Season of blood draw, %    
   Jan-Mar 37.5 16.7 13.6
   Apr-Jun 22.0 24.8 16.0
   Jul-Sept 13.0 29.5 43.6
   Oct-Dec 27.5 29.0 26.8
Tumor size, %    
   In situ 3.9 4.9 8.3
   ≤ 2 cm 44.4 51.8 51.1
   > 2- ≤ 5 cm 32.9 32.4 32.2
   > 5 cm 5.6 2.2 2.6
   Growth into chest wall/skin 5.6 2.0 1.6
   Neoadjuvant CT 7.4 6.1 4.2
   Missing 0.2 0.5 0.0
Nodal status, %*    
   0 54.4 58.2 59.6
   1-3 19.2 19.7 19.7
   4-9 6.7 6.6 4.0
   ≥ 10 7.6 3.7 4.2
   Missing 0.7 0.7 0.0
Metastases, %    
   In situ 3.9 4.9 8.3
   No 89.1 89.7 88.8
   Yes 5.6 4.9 2.2
   Missing 1.4 0.5 0.7
Tumor grade, %*    
   Low + moderate 61.1 65.1 64.5
   High 27.3 23.3 22.8
   Missing 0.2 0.5 0.2
ERPR, %*    
   ER+PR+ 55.3 55.0 50.9
   ER+PR-/ER-PR+ 19.2 15.7 20.8
   ER-PR- 14.1 17.4 15.8
   Missing 0.0 0.7 0.0
Chemotherapy, %    
   No 49.1 52.1 58.8
   Yes 48.8 47.6 41.0
   Missing 2.1 0.3 0.2
Radiotherapy, %    
   No 27.8 17.9 25.4
   Yes 72.0 82.1 74.4
   Missing 0.2 0.0 0.2
Tamoxifen/aromatase inhibitor use, %    
   No 14.8 18.9 19.3
   Yes 79.9 77.2 76.3
   Missing 5.3 3.9 4.4
Hormone replacement therapy, %    
   No 71.1 57.7 48.9
   Yes 27.8 41.5 50.0
   Missing 1.1 0.7 1.1
Diabetes, %    
   No 87.0 89.7 91.9
   Yes 13.0 10.3 7.9
   Missing 0.0 0.0 0.2
Cardiovascular disease, %    
   No 41.0 48.2 51.8
   Yes 59.0 51.8 48.2
Mode of detection, %    
   Self-detected by palpation/secretion/pain 65.3 56.3 53.5
   Physician-detected by routine investigation/mammography/ultrasound 34.5 43.5 45.4
   Missing 0.2 0.2 1.1
  1. 25(OH)D, 25-hydroxyvitamin D; BMI, body mass index; CT, chemotherapy; ERPR, estrogen receptor/progesterone receptor; SD, standard deviation.
  2. * Includes a separate category for in situ and neoadjuvant CT.