Table 1.
Overall distribution of risk factors according to breast cancer case and control status
| Characteristic | No. (%) of controls (N = 4,531) | No. (%) of cases (N = 4,911) |
|---|---|---|
| State | ||
| Wisconsin | 2,217 (48.9) | 2,884 (58.7) |
| Massachusetts | 1,665 (36.8) | 1,429 (29.1) |
| New Hampshire | 649 (14.3) | 598 (12.2) |
| Education | ||
| < High school diploma | 320 (7.1) | 293 (6.0) |
| High school diploma | 1,735 (38.3) | 1,882 (38.3) |
| Some college | 1,217 (26.9) | 1,238 (25.2) |
| ≥ College degree | 1,242 (27.4) | 1,475 (30.0) |
| Missing | 17 (0.4) | 23 (0.5) |
| Religion/Ethnicity | ||
| Not Jewish | 4,405 (97.2) | 4,777 (97.3) |
| Jewish | 77 (1.7) | 95 (1.9) |
| Missing | 49 (1.1) | 39 (0.8) |
| Body mass index (kg/m2) | ||
| < 20 | 305 (6.7) | 317 (6.5) |
| 20–24 | 1,836 (40.5) | 2,097 (42.7) |
| 25–29 | 1,436 (31.7) | 1,515 (30.8) |
| ≥ 30 | 916 (20.2) | 942 (19.2) |
| Missing | 38 (0.9) | 40 (0.8) |
| Family history of breast cancer in mother and/or sister | ||
| No | 3,870 (85.4) | 3,783 (77.0) |
| Yes | 584 (12.9) | 1,024 (20.9) |
| Unknown | 77 (1.7) | 104 (2.1) |
| Age at menarche, years | ||
| < 12 | 876 (19.3) | 1,033 (21.0) |
| 12 | 1,018 (22.5) | 1,207 (24.6) |
| 13 | 1,312 (29.0) | 1,385 (28.2) |
| 14 | 707 (15.6) | 717 (14.6) |
| ≥ 15 | 580 (12.8) | 515 (10.5) |
| Missing | 38 (0.8) | 54 (1.1) |
| Parity | ||
| 0 | 504 (11.1) | 661 (13.4) |
| 1 | 505 (11.2) | 578 (11.8) |
| 2 | 1,360 (30.0) | 1,649 (33.6) |
| 3 | 1,041 (23.0) | 1,070 (21.8) |
| ≥ 4 | 1,121 (24.7) | 953 (19.4) |
| Age at first term pregnancy, years | ||
| < 20 | 786 (19.5) | 706 (16.6) |
| 20–24 | 1,943 (48.2) | 1,893 (44.5) |
| 25–29 | 920 (22.9) | 1,121 (26.4) |
| ≥ 30 | 378 (9.4) | 530 (12.5) |
| Menopausal status | ||
| Premenopausal | 1,760 (38.8) | 1,986 (40.4) |
| Postmenopausal | 2,493 (55.1) | 2,600 (53.0) |
| Age at menopause: | ||
| < 45 | 499 (11.0) | 386 (7.9) |
| 45–49 | 512 (11.3) | 542 (11.0) |
| 50–54 | 760 (16.8) | 824 (16.8) |
| ≥ 55 | 202 (4.5) | 303 (6.2) |
| Unknown/missing | 520 (11.5) | 545 (11.1) |
| Unknown | 278 (6.1) | 325 (6.6) |
| Use of menopausal hormones | ||
| Never | 2,943 (65.0) | 3,083 (62.8) |
| Former | 241 (5.3) | 262 (5.3) |
| Current | 1,323 (29.2) | 1,535 (31.3) |
| Missing | 24 (0.5) | 31 (0.6) |
| Mammography use (previous 5 yrs) | ||
| Never | 637 (12.8) | 739 (15.0) |
| 1–2 | 1,026 (22.6) | 756 (15.4) |
| 3–4 | 551 (12.2) | 518 (10.5) |
| 5 | 1,971 (43.5) | 2,430 (49.5) |
| ≥ 6 | 315 (7.0) | 421 (8.6) |
| Missing | 41 (0.9) | 47 (1.0) |