Table 1 Characteristics of cases and control subjects

Number of women

433

1732

–

Age at breast cancer diagnosis, mean (SD)

59.0 (9.4)

–

–

Years from mammography to breast cancer, median

1.74

–

–

Invasive breast cancer, %

88

–

–

Screening detected breast cancer, %

63

–

–

Age at mammography, mean (SD)

57.4 (9.2)

57.4 (9.2)

0.99

BMI, mean (SD)

25.6 (4.6)

25.3 (4.0)

0.19

Age at menarche, mean (SD)

13.1 (1.4)

13.2 (1.5)

0.61

Parity, %

89

88

0.56

Age at first birth, mean (SD)

27.1 (5.4)

26.6 (5.2)

0.11

Current use of HRT, %

6.9

4.4

0.05

Postmenopausal, %

65

65

0.78

Breast cancer in family, %

19

13

4.5 × 10⁻⁴