Table 1.
Participant characteristics, including factors in the BWHS risk prediction model, by case–control status
| Cases (n = 922) (%) | Controls (n = 1844) (%) | |
|---|---|---|
| First-degree family history of breast cancer | ||
| Age < 50 years | ||
| No | 275 (79.3) | 575 (82.9) |
| Relative diagnosed age ≥ 50 years | 46 (13.3) | 100 (14.4) |
| Relative diagnosed age < 50 years or two relatives | 26 (7.5) | 19 (2.7) |
| Age ≥ 50 years | ||
| No | 416 (72.3) | 924 (80.3) |
| Relative diagnosed age ≥ 50 years | 109 (19.0) | 185 (16.1) |
| Relative diagnosed age < 50 years or two relatives | 50 (8.7) | 41 (3.6) |
| First-degree family history of prostate cancer | ||
| No | 728 (79.0) | 1509 (81.8) |
| Yes | 194 (21.0) | 335 (18.2) |
| Age < 50 years | ||
| Age at menarche < 14 years | 295 (85.3) | 551 (80.1) |
| Age at menarche ≥ 14 years | 51 (14.7) | 137 (19.9) |
| Age ≥ 50 years | ||
| Age at menarche < 14 years | 483 (84.0) | 887 (77.6) |
| Age at menarche ≥ 14 years | 92 (16.0) | 256 (22.4) |
| Breastfeeding (parous women only) | ||
| Never | 382 (53.1) | 840 (57.3) |
| Ever | 337 (46.9) | 625 (42.7) |
| Oral contraceptive use | ||
| Never or < 5 years | 547 (59.3) | 1266 (68.7) |
| ≥ 5 years | 375 (40.7) | 578 (31.3) |
| Bilateral oophorectomy | ||
| No | 818 (88.7) | 1625 (88.1) |
| Yes | 104 (11.3) | 219 (11.9) |
| BMI at age 18 years, kg/m2 | ||
| < 25 | 830 (91.3) | 1562 (86.3) |
| ≥ 25 | 79 (8.7) | 247 (13.7) |
| Premenopausal | ||
| BMI < 30 | 206 (64.2) | 423 (62.9) |
| BMI ≥ 30 | 115 (35.8) | 249 (37.1) |
| Postmenopausal | ||
| BMI < 30 | 214 (57.1) | 487 (58.7) |
| BMI ≥ 30 | 161 (42.9) | 342 (41.3) |
| Age < 50 years | ||
| Never biopsy or benign breast disease | 247 (71.2) | 534 (76.9) |
| Ever biopsy or benign breast disease | 100 (28.8) | 160 (23.1) |
| Age ≥ 50 years | ||
| Never biopsy or benign breast disease | 300 (52.2) | 702 (61.0) |
| Ever biopsy or benign breast disease | 275 (47.8) | 448 (39.0) |
| Mean age (SD) | 52.7 (9.3) | 52.7 (9.3) |
| Polygenic risk score, mean (SD) | 0.23 (1.00) | − 0.12 (0.98) |
| BWHS 5-year breast cancer risk percent, mean (SD) | 1.46 (0.67) | 1.32 (0.57) |