Table 1.
Baseline characteristics of patients in each of the cohorts.
| Characteristic | Intraductal Breast Cancer (N = 50,705) | Metastatic Breast Cancer (N = 5142) | P value |
|---|---|---|---|
| Age | |||
| ≤50 | 14,184 (28%) | 1153 (22.4%) | <0.001 |
| 51-64 | 19,729 (38.9%) | 1760 (34.2%) | |
| ≥65 | 16,792 (33.1%) | 2229 (43.3%) | |
| Race | |||
| White | 39,586 (78.1%) | 4198 (81.6%) | <0.001 |
| Black | 8677 (17.1%) | 709 (13.8%) | |
| Other | 2442 (4.8%) | 235 (4.6%) | |
| Charlson Deyo Score | |||
| 0 | 41,785 (82.4%) | 4186 (81.4%) | 0.102 |
| 1 | 7191 (14.2%) | 756 (14.7%) | |
| ≥2 | 1729 (3.4%) | 200 (3.9%) | |
| Insurance Status | |||
| Medicaid | 4450 (8.8%) | 359 (7.0%) | <0.001 |
| Private | 27,421 (54.1%) | 2427 (47.2%) | |
| Medicare | 16,302 (32.2%) | 2078 (40.4%) | |
| Not Insured | 1362 (2.7%) | 115 (2.2%) | |
| Other | 1170 (2.3%) | 163 (3.2%) | |
| Median Income | |||
| ≤ $62999 | 34,192 (67.4%) | 3421 (66.5%) | <0.001 |
| ≥ $63000 | 16,303 (32.2%) | 1659 (32.3%) | |
| Not recorded | 210 (0.4%) | 62 (1.2%) | |
| Facility Type | |||
| Academic | 20,410 (40.3%) | 2134 (41.5%) | 0.009 |
| Nonacademic | 27,371 (53.6%) | 2742 (53.3%) | |
| Not recorded | 3122 (6.2%) | 266 (5.2%) | |
| Year of Diagnosis | |||
| 2004–2008 | 1308 (2.6%) | 2077 (40.4%) | <0.001 |
| 2009–2013 | 49,397 (97.4%) | 3065 (59.6%) | |
| T stage | |||
| T1 | 28,839 (56.9%) | 1639 (31.9%) | <0.001 |
| T2 | 18,355 (3.62%) | 2490 (48.4%) | |
| T3 | 2530 (5.0%) | 736 (14.3%) | |
| T4 | 981 (1.9%) | 277 (5.4%) | |
| N stage | |||
| N0 | 35,750 (70.5%) | 4143 (80.6%) | <0.001 |
| N1 | 10,084 (19.9%) | 709 (13.7%) | |
| N2 | 3171 (6.3%) | 207 (4.0%) | |
| N3 | 1700 (3.4%) | 86 (1.7%) | |
| Grade | |||
| Well differentiated | 2476 (4.9%) | 698 (13.6%) | <0.001 |
| Moderately differentiated | 8006 (15.8%) | 600 (11.7%) | |
| Poorly differentiated/anaplastic | 39,426 (77.8%) | 3602 (70.1%) | |
| Not recorded | 797 (1.6%) | 242 (4.7%) | |
| Chemotherapy use | |||
| Yes | 44,365 (87.5%) | 4054 (78.8%) | <0.001 |
| No | 6340 (12.5%) | 1088 (21.2%) | |
| Hormonal therapy use | |||
| Yes | 2809 (5.5%) | 828 (16.1%) | <0.001 |
| No | 47,896 (94.5%) | 4314 (83.9%) | |
| Radiation therapy | |||
| Yes | 30,812 (60.8%) | 2698 (52.5%) | <0.001 |
| No | 19,893 (39.2%) | 2444 (47.5%) | |
| Surgery | |||
| Lumpectomy | 263,373 (52.0%) | 2247 (43.7%) | <0.001 |
| Mastectomy | 24,332 (48.0%) | 2895 (56.3%) | |
| ER status | |||
| Positive | 0 (0.0%) | 750 (14.6%) | <0.001 |
| Negative | 50,667 (99.9%) | 4187 (81.4%) | |
| Not reported | 38 (0.1%) | 205 (4.0%) | |
| PR status | |||
| Positive | 0 (0.0%) | 536 (10.4%) | <0.001 |
| Negative | 50,669 (99.9%) | 4389 (85.4%) | |
| Not reported | 36 (0.1%) | 217 (4.2%) | |
| HER2 status | |||
| Positive | 0 (0.0%) | 124 (2.4%) | <0.001 |
| Negative | 49,541 (97.7%) | 2349 (45.7%) | |
| Not reported | 1164 (2.3%) | 2669 (51.9%) | |