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Table 1 Characteristics of the study population by alcohol consumption (drinks/week) in the past year (FFQ), Norwegian EBBA-I study (n = 202)a

From: Alcohol consumption, endogenous estrogen and mammographic density among premenopausal women

Variable

Overall (n = 202)a

Low consumers (<1 drink/week) (n = 66)a

Moderate consumers (1–6 drinks/week) (n = 96)a

High consumers (≄7 drinks/week) (n = 40)a

p valueb

Characteristics

     

 Age (years)

30.7 (3.07)

31.17 (2.86)

30.75 (3.16)

29.87 (3.09)

0.105

 Education (years)

16.1 (3.02)

15.82 (2.85)

15.98 (3.04)

16.70 (3.20)

0.324

Reproductive history

 Age at menarche (years)

13.1 (1.36)

12.75 (1.29)

13.21 (1.36)

13.48 (1.36)

0.016

 Cycle length (days)

28.2 (3.17)

28.40 (4.13)

28.01 (2.78)

28.98 (3.5)

0.314

 Parous (%)

51.2

61.2

46.0

27.5

0.002

 Number of children (n)

0.91 (1.13)

1.30 (1.29)

0.80 (0.98)

0.53 (0.99)

0.001

Anthropometric measuresc

 BMI (kg/m2)

24.4 (3.77)

24.47 (2.30)

24.55 (3.56)

23.92 (3.35)

0.665

 Waist (cm)

79.5 (9.80)

76.69 (11.26)

80.28 (9.56)

77.44 (7.47)

0.300

Lifestyle factors

 Leisure time (MET/hour/week)

57.6 (88.6)

48.09 (33.44)

63.23 (121.18)

59.59 (45.16)

0.552

Oral contraceptive use

     

 Previous use (%)

82.7

76.1

85.0

90.0

0.119

 Sum use (years)

3.7 (3.7)

3.27 (3.72)

3.99 (3.69)

3.84 (3.63)

0.458

Alcohol consumption in the past year

     

 Alcohol (drinks/week)

3.46 (4.10)

0.24 (0.28)

2.67 (1.46)

10.84 (2.87)

<0.001

 Abstainers (%)

6.8

    

Smoking habits

     

 Current smokers (%)

22.1

11.9

25.0

32.5

0.030

 Former smokers (%)

45.4

32.8

50.0

55.0

0.037

Serum hormonesd

 Estradiol (pmol/l)

146.7 (61.6)

145.5 (70.49)

147.4 (62.80)

146.8 (41.04)

0.983

Salivary hormones

 Estradiol, overall averagee (pmol/l)

17.9 (8.79)

17.68 (7.65)

17.61 (9.29)

18.98 (9.40)

0.691

 Estradiol, mid-menstrualf (pmol/l)

18.20 (8.98)

17.69 (7.52)

18.05 (9.69)

19.01 (9.59)

0.839

Mammogramsg

     

 Percent mammographic density (%)

29.8 (19.0)

28.08 (19.05)

27.33 (18.02)

38.51 (19.30)

0.005

 Absolute mammographic density (cm2)

34.7 (23.4)

31.57 (21.00)

31.89 (22.73)

46.77 (25.23)

0.001

  1. Data presented as mean (standard deviation). One drink or unit is equal to 10 g alcohol
  2. BMI body mass index, EBBA-I Norwegian Energy Balance and Breast Cancer Aspects I, FFQ food frequency questionnaire, MET metabolic equivalents
  3. aNumbers may vary owing to missing information
  4. bEquality between levels were tested using one-way analysis of variation for continuous variables and the chi-square test for binary variables
  5. cMeasurements at days 1–5 after onset of menstrual cycle
  6. dSerum samples in early follicular phase: days 1–5 after onset of menstrual cycle
  7. eDaily saliva samples throughout an entire menstrual cycle
  8. fDaily saliva samples mid menstrual cycle, aligned cycle days −7 to 6
  9. gMammograms were taken days 7–12 (mid-cycle phase)
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Breast Cancer Research

ISSN: 1465-542X

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