Table 1.
Baseline characteristics of women who had and had not developed breast cancer by date of censoring in UK Biobank. Values are numbers (percentages) unless stated otherwise
| Characteristic | No breast cancer diagnosis (n=149 064) | Breast cancer diagnosis (n=7784) |
|---|---|---|
| Mean (SD) age at recruitment (years); No | 56.2 (7.9); n=149 064 | 58.9 (7.0); n=7784 |
| Mean (SD) body mass index; No | 27.0 (5.1); n=148 617 | 27.2 (4.9); n=7764 |
| Mean (SD) age at menarche; No | 13.0 (1.6); n=144 845 | 12.8 (1.6); n=7576 |
| Mean (SD) days/week strenuous physical activity; No | 1.7 (1.8); n=141 387 | 1.5 (1.8); n=7325 |
| Education: | ||
| Degree | 65 381 (44.3) | 3337 (43.3) |
| No degree | 89 383 (55.8) | 4376 (56.7) |
| Smoking: | ||
| Never | 90 072 (60.6) | 4445 (57.4) |
| Former | 46 374 (31.2) | 2700 (34.8) |
| Current | 12 131 (8.2) | 604 (7.8) |
| Alcohol use: | ||
| Never | 6254 (4.2) | 343 (4.4) |
| Former | 5208 (3.5) | 287 (3.7) |
| Current | 137 465 (92.3) | 7145 (91.9) |
| Family history of breast cancer: | ||
| Yes | 9221 (6.2) | 526 (6.8) |
| No | 139 843 (93.8) | 7258 (93.2) |
| Parity: | ||
| 0 | 27 508 (18.5) | 1489 (19.1) |
| ≥1 | 121 479 (82.5) | 6290 (80.9) |
| Oral contraceptive use: | ||
| Yes | 123 688 (83.1) | 6193 (79.7) |
| No | 25 117 (16.9) | 1580 (20.3) |
| Menopause: | ||
| Yes | 89 397 (60.0) | 5721 (73.6) |
| No | 36 272 (24.4) | 787 (10.1) |
| Not sure | 23 277 (15.6) | 1266 (16.3) |
| Hormone replacement therapy: | ||
| Yes | 57 038 (38.4) | 3142 (40.5) |
| No | 91 682 (61.7) | 4620 (59.5) |
| Shift work: | ||
| Night | 4815 (5.8) | 158 (4.6) |
| Other | 6763 (8.1) | 282 (8.2) |
| None | 71 790 (86.1) | 3014 (87.3) |