Table 1. Patient characteristics.
| Characteristic | n (%) | No surgery (%) | Surgery (%) | P value |
|---|---|---|---|---|
| Age (years) | ||||
| <35 | 336 (3.6) | 189 (3.1) | 147 (4.7) | < 0.001 |
| 35-50 | 1926 (20.8) | 1129 (18.4) | 797 (25.5) | |
| >50 | 6994 (75.6) | 4808 (78.5) | 2186 (69.8) | |
| Race (n = 9,217) | ||||
| White | 6936 (75.3) | 4603 (75.5) | 2333 (74.7) | 0.134 |
| Black | 1570 (17.0) | 1046 (17.2) | 524 (16.8) | |
| Other | 711 (7.7) | 446 (7.3) | 265 (8.5) | |
| Grade (n = 7,665) | ||||
| Well differentiated | 569 (7.4) | 386 (8.2) | 183 (6.2) | < 0.001 |
| Moderately differentiated | 3169 (41.3) | 2145 (45.4) | 1024 (34.8) | |
| Poorly/undifferentiated | 3927 (51.2) | 2195 (46.4) | 1732 (58.9) | |
| Tumor size (cm) (n = 7,504) | ||||
| ≤2 | 1264 (16.8) | 810 (17.6) | 454 (15.6) | 0.017 |
| >2-5 | 3567 (47.5) | 2193 (47.8) | 1374 (47.2) | |
| >5 | 2673 (35.6) | 1588 (34.6) | 1085 (37.2) | |
| Nodal stage (n = 8,431) | ||||
| N0 | 1893 (22.5) | 1365 (25.4) | 528 (17.3) | < 0.001 |
| N1 | 4006 (47.5) | 2831 (52.7) | 1175 (38.5) | |
| N2 | 1094 (13.0) | 496 (9.2) | 598 (19.6) | |
| N3 | 1438 (17.1) | 684 (12.7) | 754 (24.7) | |
| Breast cancer subtype | ||||
| HR+/HER2- | 5566 (60.1) | 3837 (62.6) | 1729 (55.2) | < 0.001 |
| HR+/HER2+ | 1532 (16.6) | 995 (16.2) | 537 (17.2) | |
| HR-/HER2+ | 847 (9.2) | 527 (8.6) | 320 (10.2) | |
| HR-/HER2- | 1311 (14.2) | 767 (12.5) | 544 (17.4) | |
| Marital status (n = 8,751) | ||||
| Unmarried | 4751 (54.3) | 3292 (56.9) | 1459 (49.1) | < 0.001 |
| Married | 4000 (45.7) | 2490 (43.1) | 1510 (50.9) |
HER2, human epidermal growth factor receptor; HR, hormone receptor.