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Table 1 Patient, mammographic and tumor characteristics (primary study sample)

From: Novel mammographic image features differentiate between interval and screen-detected breast cancer: a case-case study

  Study sample (n = 1403)
1C (n = 394) n (%) or mean SC (n = 1009) n (%) or mean p value Missing data
PATIENT CHARACTERISTICS
Age at diagnosis 60.8 60.2 0.055 0 %
Menopausal at diagnosis    0.150 6.4 %
 Yes 297 (81 %) 794 (84 %)   
 No 71 (19 %) 151 (16 %)   
BMI 24.8 25.8 <0.001 3.2 %
HRT use at diagnosis    <0.001 5.1 %
 No 280 (75 %) 802 (84 %)   
 Yes 93 (25 %) 156 (16 %)   
Oral contraceptive use    0.145 3.1 %
 No 78 (21 %) 239 (24 %)   
 Yes 300 (79 %) 742 (76 %)   
Parity     
 Nulliparous 61 (15 %) 158 (16 %) 0.997 2.2 %
 Number of births, parous women 2.13 2.14 0.816 0 %
 Age at first birth, parous women 25.7 25.4 0.341 0 %
Family history of breast cancer (first degree)    0.029 7.8 %
 No 284 (77 %) 762 (82 %)   
 Yes 84 (23 %) 162 (18 %)   
MAMMOGRAPHIC CHARACTERISTICS
Time (months) from measure to diagnosis 15.3 (median) 24.6 (median) <0.001  
Mammographic percent density 23.5 (median) 17.6 (median) <0.001  
TUMOR CHARACTERISTICS n (%) or mean n (%) or mean   
Tumor size, mm 19.5 15.6 <0.001 7.3 %
Lymph node metastasis    <0.001 0.4 %
 No 356 (91 %) 960 (96 %)   
 Yes 37 (9 %) 45 (4 %)   
Tumor grade, Elston    <0.001 42 %
 1 35 (16 %) 147 (25 %)   
 2 109 (50 %) 323 (54 %)   
 3 75 (34 %) 127 (21 %)   
ER status    <0.001 27 %
 Negative 57 (19 %) 72 (10 %)   
 Positive 239 (81 %) 659 (90 %)   
PR status    0.002 28 %
 Negative 109 (38 %) 201 (28 %)   
 Positive 181 (62 %) 520 (72 %)   
  1. p values for difference between the 1C and SC group were calculated by two-sided t test for continuous variables; and by chi square tests for categorical variables. See Additional file 1: Table S1 for patient and mammographic data for the validation sample
  2. 1C interval breast cancer, SC screen-detected breast cancer, BMI body mass index, HRT hormone replacement therapy, ER estrogen receptor, PR progesterone receptor