Table 1.
Characteristics of the total study population and by Tyrer–Cuzick 10‐year breast cancer risk
| Characteristics | All women | TC 10‐year breast cancer risk | ||
|---|---|---|---|---|
| <3.0% | 3.0–4.9% | ≥5.0% | ||
| Participants (n) | 57,6541 | 27,901 | 18,054 | 7,233 |
| Breast cancer cases (n) | 957 | 352 | 321 | 226 |
| Age (years), mean (SD) | 54.0 (9.7) | 51.3 (9.9) | 57.1 (8.6) | 58.2 (7.8) |
| BMI, mean (SD) | 25.2 (4.2) | 24.9 (4.3) | 25.5 (4.2) | 25.7 (4.2) |
| Age at menarche (years), mean (SD) | 13.1 (1.5) | 13.2 (1.5) | 13.0 (1.4) | 12.9 (1.4) |
| Nulliparous (%) | 12.6 | 9.6 | 15.7 | 16.4 |
| Parous women only | ||||
| Age at first birth (years), mean (SD) | 27.2 (5.3) | 26.3 (5.2) | 28.2 (5.1) | 28.5 (5.3) |
| Number of childbirths, mean (SD) | 2.2 (0.8) | 2.3 (0.8) | 2.1 (0.8) | 2.1 (0.8) |
| Family history of breast cancer (% yes) | 12.9 | 0.6 | 10.0 | 64.7 |
| Education level (%) | ||||
| Secondary school | 12.5 | 12.4 | 12.7 | 12.1 |
| Gymnasium | 30.9 | 34.2 | 28.0 | 25.8 |
| University or higher | 53.0 | 50.2 | 55.4 | 58.3 |
| Other | 3.6 | 3.2 | 3.9 | 3.8 |
| Oral contraceptive use, ever (%) | 85.3 | 86.6 | 83.9 | 83.7 |
| Premenopausal (%) | 44.1 | 57.9 | 29.2 | 24.4 |
| Postmenopausal women only | ||||
| Age at menopause (years), mean (SD) | 50.0 (5.1) | 47.7 (5.7) | 51.1 (4.3) | 51.7 (4.3) |
| MHT use (% ever) | 42.1 | 39.8 | 43.3 | 43.3 |
| Smoking status (%) | ||||
| Never | 48.6 | 50.5 | 47.0 | 45.2 |
| Past | 39.8 | 37.1 | 42.5 | 43.8 |
| Current | 11.6 | 12.5 | 10.5 | 10.9 |
| Alcohol consumption (g/day, %) | ||||
| None | 19.2 | 20.8 | 17.3 | 17.3 |
| 0.1–9.9 | 61.9 | 62.1 | 61.9 | 61.0 |
| ≥10.0 | 19.0 | 17.1 | 20.8 | 21.7 |
| Total physical activity (MET‐hr/day, %) | ||||
| <40.0 | 36.2 | 34.6 | 37.7 | 38.4 |
| 40.0–44.9 | 35.6 | 34.5 | 36.9 | 36.8 |
| ≥45.0 | 28.2 | 30.9 | 25.4 | 24.8 |
1
For 4,466 participants, of which 58 are cases, a TC risk score could not be computed.