Table 1 Characteristics of cases and controls by hormone receptor status

Number of subjects

672

158

22

308

103

3160

Age group (years old) (%)

30-39

6.4

3.2

9.1

4.9

9.7

9.7

40-49

26.5

17.1

45.5

22.4

12.6

17.8

50-59

27.8

28.5

22.7

30.8

35.0

22.1

60-69

22.9

32.9

13.6

23.1

18.5

25.2

70 ≤

16.4

18.4

9.1

18.8

24.3

25.3

Mean (years old)

56.7

59.5

52.3

57.8

58.7

59.0

SD

12.4

11.1

11.7

12.1

13.2

13.9

Menopausal status (%)^a

Premenopausal

41.1

22.2

45.5

29.9

23.3

29.6

Postmenopausal

54.4

74.0

40.9

63.3

46.6

65.1

Unknown menopausal status

4.5

3.8

13.6

6.8

30.1

5.3

Year of recruitment (%)

1997-2003

30.1

38.0

54.6

42.9

52.4

52.7

2004-2011

69.9

62.0

45.5

57.1

47.6

47.3

Referrel status (%)

From screening

21.7

20.3

18.2

15.3

7.8

18.2

Other

78.3

79.8

81.8

84.7

92.2

81.8

Area of residence (%)

Southern Miyagi prefecture

83.5

85.4

81.8

82.8

79.6

88.3

Other area

16.5

14.6

18.2

17.2

20.4

11.7

Occupation (%)

Agriculture or forestry

5.1

3.8

9.1

6.2

6.8

9.1

Industrial work or fishery

16.5

12.7

9.1

19.8

10.7

14.3

Professional or clerical work

45.2

46.8

40.9

37.7

33.0

36.0

Other^b

22.2

26.6

27.3

23.7

30.1

24.5

Missing

11.0

10.1

13.6

12.7

19.4

16.0

BMI (kg/m2, %)

< 18.5

5.1

6.3

-

5.2

9.7

5.9

18.5 ≤ < 25.0

59.4

63.9

59.1

66.6

62.1

63.9

25.0 ≤ < 30.0

26.8

24.7

40.9

22.4

21.4

25.3

30.0 ≤

8.3

5.1

-

5.5

3.9

4.0

Missing

0.5

-

-

0.3

2.9

1.0

Mean

24.0

23.5

24.2

23.3

23.0

23.4

SD

3.8

3.7

3.2

3.9

3.5

3.5

Time spent exercising (%)

Almost no

50.5

49.4

45.5

51.3

50.5

48.6

1≤ hr per week

44.1

43.7

50.0

41.6

38.8

45.2

Missing

5.5

7.0

4.6

7.1

10.7

6.2

Age at menarche (%)

≤ 12

33.8

20.9

36.4

30.2

28.2

23.3

13

22.8

21.5

22.7

22.1

20.4

19.9

14

19.1

27.9

18.2

20.8

16.5

18.9

15 ≤

20.8

25.3

18.2

22.7

26.2

30.8

Missing

3.6

4.4

4.6

4.2

8.7

7.1

Age at menopause (%)

< 48

12.3

6.0

22.2

11.8

18.8

12.5

48 ≤ < 51

30.6

29.9

22.2

24.1

41.7

26.9

51 ≤ < 54

18.6

27.4

33.3

25.1

27.1

19.7

54 ≤

13.9

15.4

11.1

12.3

12.5

8.7

Missing

24.6

21.4

11.1

26.7

0.0

32.2

Parity number (%)

0

12.1

7.6

4.6

6.2

11.7

7.9

1

10.4

9.5

18.2

13.3

8.7

9.1

2

45.5

43.7

59.1

44.8

42.7

40.8

3 ≤

24.4

29.1

9.1

28.6

27.2

33.3

Missing

7.6

10.1

9.1

7.1

9.7

9.1

Age at first birth (%)

≤ 24

31.9

38.6

9.1

37.7

36.9

41.1

25 ≤ ≤ 29

39.1

36.7

59.1

39.0

35.9

35.8

30 ≤ ≤ 50

11.2

11.4

18.2

11.0

6.8

7.3

Missing

17.9

13.3

13.6

12.3

20.4

15.9

Use of exogenous female hormone or oral contraceptives (%)

Never

81.1

79.8

90.9

83.1

76.7

78.7

Ever or current

9.8

12.0

90.9

9.7

11.7

9.1

Missing

9.1

8.2

90.9

7.1

11.7

12.3

Family history of breast cancer in mother or sister (%)

No

90.8

87.3

81.8

88.6

94.2

96.0

Yes

9.2

12.7

18.2

11.4

5.8

4.0

Alcohol drinking (%)

Never

67.6

79.8

77.3

70.5

75.7

72.6

Current or past

30.1

20.3

18.2

27.3

18.5

24.4

Missing

2.4

-

4.6

2.3

5.8

3.0

Smoking status (%)

Never

82.6

81.7

77.3

83.1

82.5

83.2

Current

12.5

11.4

13.6

12.3

12.6

12.9

Past

4.9

7.0

9.1

4.6

4.9

3.9

Passive smoking (%)

Number of subjects^c

499

116

17

241

77

2405

Never

30.1

31.0

41.2

30.3

23.4

30.9

Past

23.9

21.6

-

19.9

14.3

20.3

Current

35.3

31.0

52.9

39.0

48.1

34.4

Missing

10.8

16a.4

5.9

10.8

14.3

14.5