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Table 1 Characteristics of the women

From: Association between menopausal hormone therapy, mammographic density and breast cancer risk: results from the E3N cohort study

Characteristic All (N = 906) Controls (N = 453) Cases (N = 453)
Reference age (years)* 61 (59 to 66) 61 (59 to 66) 61 (59 to 66)
Age at mammogram (years)* 61 (58 to 65) 61 (58 to 65) 60 (58 to 65)
MHT at mammogram, N (%)
 Never 189 (20.9) 110 (24.3) 79 (17.4)
 Current 432 (47.7) 217 (47.9) 215 (47.5)
 Past, 0–2 years since last use 154 (17.0) 50 (11.0) 104 (23.0)
 Past, > 2 years since last use 131 (14.5) 76 (16.8) 55 (12.1)
Type of MHT at mammogram, N (%)
 None 189 (20.9) 110 (24.3) 79 (17.4)
 Oestrogen 30 (3.3) 15 (3.3) 15 (3.3)
 Oestrogens plus progestogens 490 (54.1) 233 (51.4) 257 (56.7)
  Oestrogen plus progesterone or dydrogesterone 138 (15.2) 79 (17.4) 59 (13.0)
  Oestrogen plus progestins 239 (26.4) 99 (21.9) 140 (30.9)
  Both 113 (12.5) 55 (12.1) 58 (12.8)
 Others 197 (21.7) 95 (21.0) 102 (22.5)
BMI at mammogram (kg/m2)* 22.9 (21.1 to 25.1) 22.8 (21.0 to 24.8) 23.1 (21.3 to 25.4)
PMD* 32 (20 to 45) 31 (17 to 43) 35 (23 to 49)
DA (cm2)* 33 (20 to 47) 29 (17 to 42) 35 (23 to 52)
NDA (cm2)* 70 (47 to 97) 72 (49 to 97) 68 (46 to 96)
ER and PR status, N (%)**
 ER+ and PR+    224 (60.6)
 ER+ and PR−    77 (20.8)
 ER− and PR+    13 (3.5)
 ER− and PR−    56 (15.1)
Family history of breast cancer in first-degree relatives, N (%)
 No 771 (85.1) 394 (87.0) 377 (83.2)
 Yes 135 (14.9) 59 (13.0) 76 (16.8)
Age of menarche (years), N (%)
 < 12 162 (17.9) 69 (15.2) 93 (20.5)
 12 244 (26.9) 125 (27.6) 119 (26.3)
 > 12 500 (55.2) 259 (57.2) 241 (53.2)
Past use of oral contraceptives, N (%)
 No 452 (49.9) 232 (51.2) 220 (48.6)
 Yes 454 (50.1) 221 (48.8) 233 (51.4)
Parity and lactation, N (%)**
 Nulliparous 116 (13.6) 59 (14.0) 57 (13.3)
 Parous without lactation 205 (24.1) 94 (22.3) 111 (25.8)
 Parous with lactation for less than 4 months 246 (28.9) 123 (29.2) 123 (28.6)
 Parous with lactation for 4 months or more 284 (33.4) 145 (34.4) 139 (32.3)
  1. For each matched case-control pair, reference age is the age at diagnosis of the case
  2. MHT menopausal hormone therapy, BMI body mass index, PMD percent mammographic density, DA dense area, NDA non-dense area, ER oestrogen receptor, PR progesterone receptor
  3. *Median (interquartile range)
  4. **Number of missing: ER/PR status, 83; Parity and lactation, 55