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Table 1 Baseline characteristics in cases and controls, CPS II Nutrition Cohort Women (1999 to 2005)*

From: Serum 25-hydroxyvitamin D concentrations and postmenopausal breast cancer risk: a nested case control study in the Cancer Prevention Study-II Nutrition Cohort

Characteristic

Cases (n = 516)

Controls (n = 516)

Pvalue‡‡

 

Mean (SD)

Age at serum collection (year)

69.5 (5.9)

69.6 (5.8)

0.7

Plasma 25(OH)D (nmol/L)

56.5 (22.0)

56.2 (22.2)

0.8

Latitude (degree)

39.0 (4.7)

39.3 (4.8)

0.2

BMI at blood collection (kg/m2)

25.9 (4.9)

25.8 (4.8)

0.9

Weight gain since age 18 (kg)

14.1 (15.5)

11.1 (18.3)

0.006

Exercise METS†

15.4 (13.8)

15.6 (14.7)

0.9

Age at menarche (years)

12.7 (1.5)

12.7 (1.4)

0.6

Age at menopause (years)

48.6 (6.1)

47.8 (6.0)

0.03

 

Percentage (%)

Family history of breast cancer

23.6

16.9

0.007

History of benign breast disease

33.9

27.5

0.01

Race

   

   White

96.7

97.1

0.7

   Other (Black/Hispanic/Oriental)

3.3

2.9

 

College graduate

24.2

23.4

0.5

Parity and age at first birth

   

   Nulliparous

9.1

8.5

0.006

   <25, 1 to 2 live births

13.2

12.4

 

   25+, 1 to 2 live births

22.5

14.7

 

   <25, 3+ live births

35.3

45.0

 

   25+, 3+ live births

20.0

19.4

 

Postmenopausal hormone use

   

   Never

22.1

25.4

0.4

   Former

58.1

53.1

 

   Current

16.1

16.7

 

Season of blood collection

   

   Dec to Feb

15.1

18.2

0.1

   Mar to May

18.8

17.4

 

   Jun to Aug

35.1

29.5

 

   Sep to Nov

31.0

34.9

 

Alcohol intake (≥ 1 drink/day)

21.3

16.1

0.1

Multivitamin use containing vitamin D‡

   

   Not current user

30.8

34.9

0.6

   Current user

63.6

59.6

 

Calcium supplement use

   

   Not current user

32.4

32.9

0.5

   Current user

59.9

57.3

 

Vitamin D supplement use§

   

   Not current user

54.1

53.7

0.9

   Current user

16.1

16.9

 
 

Mean (SD)

Dietary variables #

   

   Total calcium (mg/day)

1358.0 (565.2)

1293.7 (576.6)

0.08

   Dietary calcium (mg/day)

777.0 (285.3)

768.6 (283.0)

0.6

   Supplemental calcium (mg/day)

581.0 (504.3)

515.0 9493.4)

0.08

   Total vitamin D (IU/day)

439.5 (243.6)

415.0 (239.7)

0.1

   Dietary vitamin D (IU/day)

192.0 (105.3)

187.6 (96.1)

0.5

  1. * Standardized to age distribution of the study population.
  2. † Metabolic equivalent of task (METS) are defined for each type of exercise-related physical activity as a multiple of metabolic equivalent of sitting quietly for one hour.
  3. ‡ Reported on the 1999 questionnaire.
  4. § Reported at blood collection.
  5. # All dietary variables are adjusted for energy intake which was estimated from the 1992 brief Block Food Frequency Questionnaire (FFQ).
  6. ‡‡†† P values for categorical variables are based on the chi-squared test and P values for continuous variables are based on the t-test for difference of means.
  7. 25(OH)D = 25-hydroxyvitamin D; BMI = body mass index; CPS-II = Cancer Prevention Study-II; SD = standard deviation.
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Breast Cancer Research

ISSN: 1465-542X

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