Table 1 Breast cancer risk factors by density measurs (quintiles* in controls (N = 859)

Age at examination (years)

60.3 (5.3)

60.6 (5.5)

59.1 (5.4)

58.8 (5.7)

56.7 (5.3)

<0.001

57.2 (5.1)

57.8 (5.3)

59.7 (5.4)

59.8 (5.5)

60.9 (5.6)

<0.001

BMI (kg/m²)

27.7 (4.1)

26.4 (4.0)

25.6 (3.5)

25.3 (3.7)

25.1 (3.9)

<0.001

22.9 (2.4)

24.4 (2.5)

25.9 (2.8)

26.9 (3.3)

30.0 (4.4)

<0.001

Height (cm)

163.4 (5.8)

163.8 (7.2)

164.1 (6.3)

164.4 (6.7)

165.0 (5.5)

0.02

164.7 (5.8)

164.3 (6.5)

163.6 (5.9)

164.0 (6.8)

164.0 (6.5)

0.20

Age at menarche(years)

13.4 (1.6)

13.5 (1.7)

13.3 (1.5)

13.5 (1.7)

13.3 (1.5)

0.72

13.6 (1.5)

13.4 (1.7)

13.4 (1.6)

13.2 (1.6)

13.3 (1.6)

0.05

Age at menopause (years)

47.1 (6.1)

47.9 (5.5)

47.1 (5.6)

48.0 (5.5)

46.9 (5.9)

0.87

47.8 (4.9)

47.4 (6.1)

47.2 (5.9)

47.1 (5.9)

47.5 (5.7)

0.45

Nr. of children^†

2.9 (1.4)

2.6 (1.6)

2.5 (1.5)

2.3 (134)

2.1 (1.4)

<0.001

2.1 (1.3)

2.3 (1.5)

2.6 (1.4)

2.7 (1.6)

2.8 (1.5)

<0.001

Age at first delivery (years)^‡

25.0 (4.0)

25.4 (4.5)

24.8 (3.8)

25.2 (3.7)

24.9 (4.1)

0.87

25.4 (3.6)

24.9 (3.9)

24.7 (3.8)

25.4 (4.5)

25.0 (4.3)

0.79

Nulliparous

9 (5.2)

16 (9.3)

20 (11.7)

23 (13.4)

33 (19.2)

<0.001

32 (18.6)

23 (13.5)

17 (9.9)

16 (9.2)

13 (7.6)

0.001

HT use (ever)

32 (18.6)

40 (23.3)

39 (22.8)

56 (32.7)

50 (29.1)

<0.01

50 (29.2)

48 (28.1)

41 (23.8)

39 (22.5)

39 (22.8)

0.08

Pill use (ever)

106 (61.6)

117 (68.4)

107 (62.6)

112 (65.1)

109 (63.4)

0.99

112 (65.1)

107 (62.6)

115 (66.9)

110 (63.6)

107 (62.9)

0.77

Family history of breast cancer

28 (16.7)

20 (12.0)

27 (16.0)

23 (14.0)

26 (15.6)

0.99

29 (17.4)

25 (14.8)

21 (12.4)

20 (12.0)

29 (17.7)

0.80