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Table 2 Baseline characteristics of breast cancer cases and controls.

From: SNP-SNP interactions in breast cancer susceptibility

 

Cases

Controls

Pvalue#

 

n

%

n

%

 

Overall

398

 

372

  

Age*

     

≤ 40

79

19.8

69

18.6

0.08

41–45

106

26.6

98

26.4

 

46–50

144

36.2

113

30.4

 

51–55

69

17.3

91

24.5

 

Missing

0

-

1

-

 

Mean (SD)

44.8

(6.2)

45.2

(6.6)

0.37

BMI

     

<18.5

7

2.2

4

1.1

0.05

18.5 – 25

178

55.1

166

46.0

 

25 – 30

81

25.1

116

32.1

 

> 30

57

17.6

75

20.8

 

Missing

75

-

11

-

 

Mean (SD)

25.7

(5.4)

26.3

(5.5)

0.14

Education

     

Up to high school

122

35.4

101

27.2

0.06

Technical school

27

7.8

34

9.2

 

Some college/University

196

56.8

236

63.4

 

Missing

53

-

1

-

 

Smoking status

     

Ever smoked

184

53.2

209

56.3

0.40

Never smoked

162

46.8

162

43.7

 

Missing

52

-

1

-

 

Family History

     

Yes

86

21.6

34

9.2

<10-5

No

312

78.4

337

90.8

 

Missing

0

-

1

-

 

Menopausal status

     

Pre-menopausal

296

84.0

261

82.1

0.42

Post-menopausal

56

16.0

57

17.9

 

Missing

46

-

54

-

 

Age at menarche

     

Age ≤ 12

154

45.2

177

48.1

0.43

Age > 12

187

54.8

191

51.9

 

Missing

57

-

4

-

 

Age period stopped

     

Pre-menopausal

296

84.6

261

82.1

0.68

Age ≤ 49

39

11.1

42

13.2

 

Age > 49

15

4.3

15

4.7

 

Missing

48

-

54

-

 

Parity (# of live births)

     

Nulliparous

68

19.6

63

17.0

0.85

1 child

56

16.1

57

15.4

 

2 children

145

41.8

157

42.3

 

≥ 3 children

78

22.4

94

25.3

 

Missing

51

-

1

-

 

Age at 1 st live birth

     

Nulliparous

68

19.7

63

17.0

0.63

≤ 24 years

126

36.4

136

36.7

 

> 24 years

152

43.9

172

46.4

 

Missing

52

-

1

-

 
  1. *Age of first breast cancer diagnosis for cases and age at interview for controls
  2. Uncertain or missing data
  3. Women with first-degree relatives with breast cancer
  4. # χ2 test for categorical variables or Student's t test (equal variance) for continuous variables