Table 2 Characteristics of the study population according to 10-year breast cancer risk estimated by the Tyrer–Cuzick prediction model
Breast cancer risk | |||
|---|---|---|---|
Characteristic | <3.0% | 3.0 to 4.9% | ≥5.0% |
Number of participants (%) | 19,633 (50.5) | 13,785 (35.4) | 5,495 (14.1) |
Age at mammography screening (years), mean (SD) | 52.8 (10.4) | 57.9 (8.5) | 58.8 (7.8) |
Body mass index (kg/m2), mean (SD) | 25.1 (4.2) | 25.7 (4.2) | 25.8 (4.1) |
Age at menarche (years), mean (SD) | 13.2 (1.5) | 13.0 (1.4) | 12.9 (1.4) |
Nulliparous (%) | 8.4 | 16.0 | 16.5 |
Age at first birth (years), mean (SD)a | 26.0 (5.0) | 28.2 (5.0) | 28.4 (5.2) |
Number of childbirths, mean (SD)a | 2.3 (0.8) | 2.1 (0.8) | 2.1 (0.8) |
Family history of breast cancer (%) | 1.2 | 9.9 | 67.2 |
Education level (%) | |||
Secondary school | 14.1 | 13.6 | 12.6 |
High school | 33.9 | 27.5 | 26.7 |
University or higher | 49.0 | 55.5 | 57.5 |
Other | 2.7 | 3.2 | 3.1 |
OC use, ever (%) | 80.9 | 79.9 | 79.8 |
Premenopausal (%) | 56.7 | 30.8 | 27.9 |
Age at menopause (years), mean (SD)b | 49.5 (5.5) | 50.2 (5.2) | 50.3 |
HRT use (%)b | |||
Never | 63.1 | 61.4 | 62.2 |
Past | 22.4 | 22.2 | 22.8 |
Current | 3.8 | 6.0 | 5.9 |
Smoking status (%) | |||
Never | 49.9 | 46.2 | 44.3 |
Past | 36.9 | 42.7 | 43.7 |
Current | 12.9 | 11.0 | 11.9 |
Alcohol consumption (grams/day) | |||
None (%) | 19.3 | 16.4 | 16.3 |
0.1 to 9.9 (%) | 61.6 | 61.3 | 59.5 |
10.0 to 29.9 (%) | 14.7 | 17.5 | 18.8 |
≥ 30.0 (%) | 2.1 | 3.3 | 3.5 |