Table 1.
Demographic and clinical characteristics of case patients in Carolina Breast Cancer Study phases I, II, and III by immunohistochemical-defined estrogen receptor category
| Characteristic | ER expression |
||
|---|---|---|---|
| <1% (n = 757; 26.5%) | ≥1–<10% (n = 217; 7.6%) | ≥10% (n = 1885; 65.9%) | |
| Study phase, No. (%) | |||
| 1 | 66 (8.7) | 60 (27.7) | 133 (7.1) |
| 2 | 150 (19.8) | 17 (7.8) | 276 (14.6) |
| 3 | 541 (71.5) | 140 (64.5) | 1476 (78.3) |
| Age at diagnosis, No. (%), y | |||
| <50 (referent) | 432 (57.1) | 127 (58.5) | 857 (45.5) |
| ≥50 | 325 (42.9) | 90 (41.5) | 1028 (54.5) |
| RFD* (95% CI), % | −9.6 (−12.9 to −6.3) | −4.9 (−7.7 to −2.3) | Referent |
| P† | <.001 | <.001 | |
| Menopausal status, No. (%) | |||
| Premenopausal (referent) | 373 (49.3) | 115 (53.0) | 785 (41.6) |
| Postmenopausal | 384 (50.7) | 102 (47.0) | 1100 (58.4) |
| RFD* (95% CI), % | −6.5 (−9.9 to −3.2) | −4.3 (−6.9 to −1.6) | Referent |
| P† | <.001 | .002 | |
| Race, No. (%) | |||
| White (referent) | 288 (38.0) | 118 (54.4) | 1103 (58.5) |
| AA/Black | 469 (62.0) | 99 (46.6) | 782 (41.5) |
| RFD* (95% CI), % | 16.1 (12.6 to 19.4) | 1.4 (−1.1 to 3.9) | Referent |
| P† | <.001 | .26 | |
| PR status, No. (%)‡ | |||
| Positive (referent) | 86 (11) | 96 (44) | 1613 (86) |
| Negative | 665 (89) | 121 (56) | 264 (14) |
| RFD* (95% CI), % | 65.7 (62.5 to 68.9) | 25.6 (20.8 to 30.4) | Referent |
| P† | <.001 | <.001 | |
| HER2 status, No. (%)§ | |||
| Negative | 595 (78.7) | 141 (65.0) | 1427 (75.8) |
| Positive | 123 (16.3) | 47 (21.7) | 273 (14.5) |
| Missing | 38 (5.0) | 29 (13.3) | 183 (9.7) |
| Combined grade, No. (%)|| | |||
| 1 | 13 (2.2) | 30 (18.1) | 448 (29.7) |
| 2 | 84 (14.4) | 45 (27.1) | 711 (47.2) |
| 3 | 485 (83.3) | 91 (54.8) | 349 (23.1) |
| RFD, grade 3 vs grade 1/2* (95% CI), % | 48.6 (44.8 to 52.5) | 13.6 (9.5 to 17.7) | Referent |
| P† | <.001 | <.001 | |
| Tumor size, No. (%), cm|| | |||
| ≤2 | 318 (42.8) | 99 (46.7) | 1130 (60.7) |
| >2–≤5 | 337 (45.4) | 93 (43.9) | 583 (31.3) |
| >5 | 88 (11.8) | 20 (9.4) | 149 (8.0) |
| RFD, >2 vs ≤2 (95% CI), %* | 5.7 (−0.7 to 12.2) | 0.0 (−5.1 to 5.1) | Referent |
| P† | .08 | .99 | |
| Node status, No. (%)|| | |||
| Negative (referent) | 448 (59.4) | 134 (62.0) | 1187 (63.2) |
| Positive | 306 (40.6) | 82 (38.0) | 691 (36.8) |
| RFD* (95% CI), % | 0.8 (−2.6 to 4.2) | −0.3 (−2.9 to 2.3) | Referent |
| P† | .64 | .82 | |
| Stage, No. (%)|| | |||
| I | 232 (31.0) | 88 (41.3) | 904 (48.5) |
| II | 386 (52.5) | 85 (39.9) | 712 (38.2) |
| III | 112 (15.0) | 34 (16.0) | 198 (10.6) |
| IV | 19 (2.5) | 6 (2.8) | 49 (2.6) |
| RFD, III/IV vs I/II* (95% CI), % | 4.9 (0 to 9.9) | 3.3 (−0.9 to 7.4) | Referent |
| P† | .05 | .13 | |
*
Relative frequency differences (RFD) adjusted for age and race (except for race models, which were adjusted for age only, and age and menopausal status models, which were adjusted for race only). AA = African American; CI = confidence interval; ER = estrogen receptor; PR = progesterone receptor.
†
Two-sided χ2 test.
‡
Fourteen case patients had missing PR status.
§
RFD not calculated because of uneven missingness across ER category.
|
A total of 603 case patients had missing grade, 42 had missing size, 11 had missing node status, and 34 had missing stage.