Table 1.
Descriptive characteristics of breast cancer cases and controls by race
| Variable | All women |
Whites |
African Americans |
|||
|---|---|---|---|---|---|---|
| Cases | Controls | Cases | Controls | Cases | Controls | |
| No of subjects | 491 | 528 | 297 | 324 | 194 | 204 |
| Mean age (CBCS), yearsa | 53.2 (28–74) | 54.0 (31–74) | 53.9 (28–74) | 54.5 (35–74) | 52.0 (30–74) | 53.3 (31–74) |
| Mean age (CMR), yearsb | 53.2 (28–77) | 54.5 (34–76) | 53.9 (28–77) | 54.8 (35–76) | 52.0 (30–74) | 53.9 (34–76) |
| Mean BMIb | 28.6 (15.1, 60.6) | 28.8 (14.6, 60.9) | 26.5 (17.2, 49.5) | 26.8 (16.2, 52.9) | 32.0 (15.1, 60.6) | 32.1 (14.6, 60.9) |
| Mean number of daysc | −21 (−1401, 365) | 149 (−1617, 1095) | −29 (−1401, 365) | 133 (−1526, 1095) | −9 (−1210, 365) | 175 (−1617, 1078) |
| Breast density | ||||||
| Almost entirely fat | 13 (2.7 %) | 25 (4.7 %) | 5 (1.7 %) | 10 (3.1 %) | 8 (4.1 %) | 15 (7.4 %) |
| Scattered fibroglandular densities | 183 (37.3 %) | 197 (37.3 %) | 98 (33.0 %) | 108 (33.3 %) | 85 (43.8 %) | 89 (43.6 %) |
| Heterogeneously dense | 232 (47.3 %) | 253 (47.9 %) | 144 (48.5 %) | 171 (52.8 %) | 88 (45.4 %) | 82 (40.2 %) |
| Extremely dense | 63 (12.8 %) | 53 (10.0 %) | 50 (16.8 %) | 35 (10.8 %) | 13 (6.7 %) | 18 (8.8 %) |
| Menopausal status | ||||||
| Premenopausal | 200 (40.7 %) | 213 (40.3 %) | 120 (40.4 %) | 127 (39.2 %) | 80 (41.2 %) | 86 (42.2 %) |
| Postmenopausal | 291 (59.3 %) | 315 (59.7 %) | 177 (59.6 %) | 197 (60.8 %) | 114(58.8 %) | 118 (57.8 %) |
| Family historyd | ||||||
| No | 386 (81.1 %) | 440 (85.6 %) | 232 (80.1 %) | 263 (83.0 %) | 154 (82.4 %) | 177 (89.9 %) |
| Yes | 90 (18.9 %) | 74 (14.4 %) | 57 (19.7 %) | 54 (17.0 %) | 33 (17.6 %) | 20 (10.2 %) |
| Missingf | 15 | 14 | 8 | 7 | 7 | 7 |
| Age at menarche | ||||||
| <13 | 257 (52.3 %) | 230 (43.6 %) | 148 (49.8 %) | 135 (41.7 %) | 109 (56.2 %) | 95 (46.6 %) |
| ≥13 | 234 (47.7 %) | 298 (56.4 %) | 149 (50.2 %) | 189 (58.3 %) | 85 (43.8 %) | 109 (53.4 %) |
| Parity and age at FFTPe | ||||||
| Nulliparous | 74 (15.1 %) | 67 (12.7 %) | 39 (13.1 %) | 45 (13.9 %) | 35 (18.0 %) | 22 (10.8 %) |
| Parous, <26 | 312 (63.5 %) | 347 (65.7 %) | 178 (59.9 %) | 200 (61.7 %) | 134 (69.1 %) | 147 (72.1 %) |
| Parous 26+ | 105 (21.4 %) | 114 (21.6 %) | 80 (26.9 %) | 79 (24.4 %) | 25 (12.9 %) | 35 (17.2 %) |
| Breastfeeding | ||||||
| Never | 299 (60.9 %) | 324 (61.4 %) | 163 (54.9 %) | 201 (62.0 %) | 136 (70.1 %) | 123 (60.3 %) |
| Ever | 192 (39.1 %) | 204 (38.6 %) | 134 (45.1 %) | 123 (38.0 %) | 58 (29.9 %) | 81 (39.7 %) |
| Lifetime duration lactation | ||||||
| Never | 299 (60.9 %) | 324 (61.4 %) | 163 (54.9 %) | 201 (62.0 %) | 136 (70.1 %) | 123 (60.2 %) |
| >0–3 months | 72 (14.7 %) | 69 (13.1 %) | 58 (19.5 %) | 45 (13.9 %) | 14 (7.2 %) | 24 (11.8 %) |
| 4+ months | 120 (24.4 %) | 135 (25.6 %) | 76 (25.6 %) | 78 (24.1 %) | 44 (22.7 %) | 57 (27.9 %) |
| Current HT use at the time of the mammogram | ||||||
| No | 359 (73.6 %) | 336 (65.0 %) | 193 (65.4 %) | 182 (57.2 %) | 166 (86.1 %) | 154 (77.4 %) |
| Yes | 129 (26.4 %) | 181 (35.1 %) | 102 (34.6 %) | 136 (42.8 %) | 27 (14.0 %) | 45 (22.6 %) |
| Missingf | 3 | 11 | 2 | 6 | 1 | 5 |
| Oral contraceptive use | ||||||
| Never | 170 (34.6 %) | 170 (32.4 %) | 95 (32.0 %) | 89 (27.6 %) | 75 (38.7 %) | 81 (39.9 %) |
| Ever | 321 (65.4 %) | 355 (67.6 %) | 202 (68.0 %) | 233 (72.4 %) | 119 (61.3 %) | 122 (60.1 %) |
| Missingf | 0 | 3 | 0 | 2 | 0 | 1 |
| WHRe | ||||||
| <0.77 | 132 (27.3 %) | 169 (32.3 %) | 110 (37.2%) | 133 (41.3 %) | 22(11.7 %) | 36 (17.8 %) |
| 0.77–0.83 | 171 (35.3 %) | 173 (33.0 %) | 110 (37.2%) | 105 (32.6 %) | 61 (32.5 %) | 68 (33.7 %) |
| ≥0.84 | 181 (37.4 %) | 182 (34.7 %) | 76 (25.7 %) | 84 (26.1 %) | 105 (55.9 %) | 98 (48.5 %) |
| Missingf | 7 | 4 | 1 | 2 | 6 | 2 |
a
Mean (range) age at diagnosis for cases and selection for controls in the CBCS
b
Mean (range) age at the time of the mammogram in the CMR
c
Mean (range) number of days between diagnosis date for cases and selection date for controls in the CBCS and the date of the mammogram chosen to assess breast density
d
First-degree family history of breast cancer
e
FFTP first full-term pregnancy, WHR waist-to-hip ratio
f
Missing values were excluded from percentage calculations