Table 1.
Baseline Characteristics of breast cancer cases and controls
| Characteristic | Case (n=191) | Control (n=194) |
|---|---|---|
| n (%)1 | n (%)1 | |
| At Baseline | ||
| Age, mean (SD) | 63.0 (7.0) | 62.9 (7.0) |
| Gail 5 year risk* | ||
| <1.26 | 66 (34.6) | 69 (35.6) |
| 1.27 – 1.80 | 54 (28.3) | 64 (33.0) |
| >1.80 | 71 (37.2) | 61 (31.4) |
| Ethnicity | ||
| White | 154 (80.6) | 157 (80.9) |
| Black | 24 (12.6) | 24 (12.4) |
| Hispanic | 9 (4.7) | 9 (4.6) |
| American Indian | 3 (1.6) | 3 (1.6) |
| Unknown | 1 (0.5) | 1 (0.5) |
| BMI, mean (SD) | 28.4 (6.0) | 28.6 (6.5) |
| Percent fat from whole body scan, mean (SD) | 44.0 (6.7) | 44.3 (7.7) |
| Smoking | ||
| Never | 92 (48.4) | 100 (52.9) |
| Past | 85 (44.7) | 70 (37.0) |
| Current | 13 (6.8) | 19 (10.0) |
| Estrogen + progestin menopausal hormone therapy | ||
| Never used | 131 (68.6) | 151 (77.8) |
| Past user | 18 (9.4) | 10 (5.2) |
| Current user | 42 (22.0) | 33 (17.0) |
| Unopposed estrogen menopausal hormone therapy | ||
| Never used | 127 (66.5) | 126 (65.3) |
| Past user | 27 (14.1) | 27 (14.0) |
| Current user | 37 (19.4) | 40 (20.7) |
| Age at menopause, mean (SD) | 48.7 (6.4) | 47.8 (6.9) |
| Age at first birth | ||
| Never pregnant /No term pregnancy | 19 (10.8) | 21 (12.4) |
| <20 | 29 (16.5) | 27 (16.0) |
| 20 – 29 | 116 (65.9) | 110 (65.1) |
| 30+ | 12 (6.8) | 11 (6.5) |
| Parity (among those with term pregnancy) | ||
| 1–2 | 63 (36.6) | 65 (37.6) |
| 3–4 | 75 (43.6) | 77 (44.5) |
| 5+ | 34 (19.8) | 31 (17.9) |
| Percent Calories from Fat, mean (SD) | 33.7 (8.1) | 33.7 (8.2) |
| WHI study | ||
| Observational | 119 (62.3) | 121 (62.4) |
| Clinical Trial | 72 (37.7) | 73 (37.6) |
| Outcomes/Exposures | ||
| Age at diagnosis,2 mean (SD) | 71.4 (7.8) | 78.1 (7.4) |
| Estrogen receptor | ||
| Positive | 148 (77.5) | - |
| Negative | 26 (13.6) | - |
| Unknown/Borderline | 17 (8.9) | - |
| Progesterone receptor | ||
| Positive | 130 (68.1) | - |
| Negative | 41 (21.5) | - |
| Unknown/Borderline | 20 (10.5) | - |
| Her2 receptor | ||
| Positive | 21 (11.0) | - |
| Negative | 107 (56.0) | - |
| Unknown/Borderline | 14 (33.0) | - |
*
tertiled
1.
Mean (SD) where indicated
2.
For controls, age at diagnosis was calculated as age at last known follow-up date