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Table 2 Associations of reproductive variables with the percentage of different tissue types (log-transformed) in benign breast biopsy samples (β coefficients and 95% confidence intervals)

From: Associations of reproductive breast cancer risk factors with breast tissue composition

Reproductive factor

Number

Tissue type

% epithelial

% stroma

% fat

% fibroglandulara

Nulliparityb

 Nulliparous

86

− 0.26 (− 0.41; − 0.11)

0.04 (0.01; 0.08)

− 0.34 (− 0.54; − 0.13)

0.01 (− 0.02; 0.05)

 Parous

880

Ref

Ref

Ref

Ref

Breastfeeding, monthsc

 0 to < 1

361

Ref

Ref

Ref

Ref

 1 to < 12

279

0.03 (− 0.07; 0.13)

0.02 (− 0.01; 0.04)

− 0.06 (− 0.18; 0.07)

0.01 (− 0.01; 0.04)

 12 to < 24

119

0.08 (− 0.05; 0.22)

0.01 (− 0.03; 0.04)

− 0.05 (− 0.22; 0.12)

0.01 (− 0.03; 0.04)

 ≥ 24

57

0.04 (− 0.15; 0.23)

0.02 (− 0.03; 0.08)

− 0.30 (− 0.54; − 0.06)

0.03 (− 0.02; 0.07)

 p-trend

816

0.39

0.43

0.04

0.34

Parityd

 1

82

Ref

Ref

Ref

Ref

 2

292

0.11 (− 0.05; 0.27)

− 0.02 (− 0.06; 0.02)

− 0.05 (− 0.25; 0.15)

0.01 (− 0.03; 0.05)

 3

269

0.12 (− 0.05; 0.28)

− 0.03 (− 0.08; 0.01)

0.01 (− 0.19; 0.22)

− 0.01(− 0.05; 0.03)

 ≥ 4

223

0.16 (− 0.02; 0.33)

− 0.05 (− 0.10; − 0.00)

0.04 (− 0.18; 0.26)

− 0.02(− 0.06; 0.03)

p-trend

866

0.13

0.02

0.32

0.17

Parity continuousd

866

0.03 (− 0.00; 0.07)

− 0.01 (− 0.02; − 0.00)

0.01 (− 0.03; 0.06)

− 0.01 (− 0.01; 0.00)

Age at first child’s birthe

 < 25

445

ref

ref

ref

ref

 25–29

331

0.12 (0.03; 0.21)

− 0.01 (− 0.03; 0.02)

− 0.09 (− 0.20; 0.03)

0.01 (− 0.01; 0.03)

 ≥ 30

90

0.07 (− 0.08; 0.23)

− 0.03 (− 0.07; 0.01)

− 0.04 (− 0.23; 0.15)

− 0.01 (− 0.05; 0.03)

 p-trend

866

0.13

0.16

0.44

0.85

Age at first birth continuous (per 5 years)e

866

0.04 (− 0.02; 0.11)

− 0.01 (− 0.02; 0.01)

− 0.03 (− 0.11; 0.05)

− 1.8 × 10−3 (− 0.01; 0.02)

Age at menarchef

 < 12

176

− 0.09 (− 0.22; 0.04)

− 0.01 (− 0.05; 0.02)

0.07 (− 0.12; 0.25)

− 0.01 (− 0.05; 0.02)

 12

275

− 0.13 (− 0.24; − 0.01)

− 0.04 (− 0.07; − 0.01)

0.10 (− 0.06; 0.26)

− 0.05 (− 0.07; − 0.02)

 13

287

− 0.06 (− 0.17; 0.05)

− 0.03 (− 0.06; − 0.00)

− 0.01 (− 0.17; 0.15)

− 0.03 (− 0.05; − 0.00)

 > 13

228

ref

ref

ref

ref

 p-trend

966

0.07

0.23

0.24

0.11

Age at menarche continuous (per 5 years)f

966

0.15 (− 0.01, 0.30)

0.02 (− 0.02, 0.06)

− 0.11 (− 0.33, 0.11)

0.03 (− 0.01, 0.06)

Time between menarche and age at first birth, continuous (per 5 years)g

866

0.02 (− 0.04; 0.08)

− 0.01 (− 0.02; 0.01)

− 0.01 (− 0.09; 0.06)

− 1.7 × 10−3 (− 0.02; 0.01)

Time since the last pregnancy, continuous (per 5 years)c

839

− 0.05 (− 0.12; 0.02)

− 0.02 (− 0.04 –3.0 × 10−3)

0.05 (− 0.03; 0.14)

− 0.02 (− 0.04; − 3.0 × 10−3)

  1. aFibroglandular tissue represents combined epithelium and stroma
  2. bAdjusted for age (continuous), BMI (continuous), age at menarche (< 12, 12, 13, > 13), a family history of breast cancer (yes/no), menopausal status/postmenopausal hormone use (premenopausal, postmenopausal/no hormones, postmenopausal/past hormones, postmenopausal/current hormones, postmenopausal/unknown hormone use status), NHS cohort (NHSI, NHSII), and alcohol use (none, > 0 to < 5, ≥ 5 g/day)
  3. cAmong parous women only: adjusted for age (continuous), BMI (continuous), age at menarche (< 12, 12, 13, > 13), parity, age at first child’s birth, a family history of breast cancer (yes/no), menopausal status/postmenopausal hormone use (premenopausal, postmenopausal/no hormones, postmenopausal/past hormones, postmenopausal/current hormones, postmenopausal/unknown hormone use status), NHS cohort (NHSI, NHSII), and alcohol use (none, > 0 to < 5, ≥5 g/day)
  4. dAmong parous women only: adjusted for age (continuous), BMI (continuous), age at first birth, age at menarche (< 12, 12, 13, > 13), a family history of breast cancer (yes/no), menopausal status/postmenopausal hormone use (premenopausal, postmenopausal/no hormones, postmenopausal/past hormones, postmenopausal/current hormones, postmenopausal/unknown hormone use status), NHS cohort (NHSI, NHSII), and alcohol use (none, > 0 to < 5, ≥5 g/day)
  5. eAmong parous women only: adjusted for age (continuous), BMI (continuous), parity, age at menarche (< 12, 12, 13, > 13), a family history of breast cancer (yes/no), menopausal status/postmenopausal hormone use (premenopausal, postmenopausal/no hormones, postmenopausal/past hormones, postmenopausal/current hormones, postmenopausal/unknown hormone use status), NHS cohort (NHSI, NHSII), and alcohol use (none, > 0 to < 5, ≥5 g/day)
  6. fAdjusted for age (continuous), BMI (continuous), parous status (nulliparous, parous), a family history of breast cancer (yes/no), menopausal status/postmenopausal hormone use (premenopausal, postmenopausal/no hormones, postmenopausal/past hormones, postmenopausal/current hormones, postmenopausal/unknown hormone use status), NHS cohort (NHSI, NHSII), and alcohol use (none, > 0 to < 5, ≥5 g/day)
  7. gAmong parous women only: adjusted for age (continuous), BMI (continuous), parity, a family history of breast cancer (yes/no), menopausal status/postmenopausal hormone use (premenopausal, postmenopausal/no hormones, postmenopausal/past hormones, postmenopausal/current hormones, postmenopausal/unknown hormone use status), NHS cohort (NHSI, NHSII), and alcohol use (none, > 0 to < 5, ≥ 5 g/day)
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Breast Cancer Research

ISSN: 1465-542X

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