Table 1 Age-adjusted characteristics of women at the time of the biopsy, stratified by menopausal status and parity
From: Associations of reproductive breast cancer risk factors with breast tissue composition
Characteristic | Premenopausal, n = 601 | Postmenopausal, n = 290 | ||
|---|---|---|---|---|
Nulliparous, n = 61 | Parous, n = 540 | Nulliparous, n = 21 | Parous, n = 269 | |
Mean (SD) | ||||
 % epithelium | 8.8 (4.8) | 10.4 (7.0) | 4.6 (2.8) | 7.2 (6.1) |
 % stroma | 76.1 (10.3) | 74.5 (11.0) | 74.0 (10.7) | 67.3 (12.6) |
 % fat | 15.1 (11.2) | 15.1 (10.9) | 21.3 (9.9) | 25.5 (13.5) |
 % fibroglandular tissuea | 84.9 (11.2) | 84.9 (10.9) | 78.7 (9.9) | 74.5 (13.5) |
Age (years)b | 36.2 (7.4) | 41.5 (7.3) | 55.1 (7.5) | 57.3 (6.5) |
Age at menopause (years) | NA | NA | 44.5 (4.9) | 48.4 (5.1) |
Body mass index (kg/m2) | 24.2 (5.4) | 24.1 (4.5) | 24.5 (2.4) | 25.1 (4.0) |
Alcohol use (g/day) | 4.2 (4.7) | 5.4 (8.8) | 4.3 (3.8) | 5.5 (8.6) |
Parity | NA | 2.7 (1.2) | NA | 3.2 (1.5) |
Age at first birth (years) | NA | 25.1 (3.6) | NA | 24.9 (3.2) |
Age at menarche (years) | 13.0 (1.1) | 12.5 (1.4) | 12.9 (0.8) | 12.7(1.3) |
Percentagesc | ||||
 Breastfeeding | ||||
  0 to < 1 month | NA | 41 | NA | 50 |
  1 to < 12 months | NA | 32 | NA | 37 |
  12 to < 24 months | NA | 18 | NA | 10 |
  ≥ 24 months | NA | 10 | NA | 3 |
 Family history of breast cancer | 10 | 10 | 22 | 17 |
 Smoking status | ||||
  Never smoked | 61 | 56 | 24 | 49 |
  Past smoker | 20 | 28 | 45 | 34 |
  Current smoker | 20 | 16 | 31 | 17 |
 Postmenopausal hormone use | ||||
  Never used | NA | NA | 12 | 29 |
  Past use | NA | NA | 3 | 21 |
  Current use | NA | NA | 74 | 32 |
  Unknown status | NA | NA | 12 | 18 |
 Benign breast disease subtypes | ||||
  Non-proliferative | 23 | 32 | 39 | 27 |
  Proliferative without atypia | 70 | 58 | 45 | 55 |
  Proliferative with atypia | 7 | 10 | 15 | 18 |