Table 1 Characteristics of patients with or without surgical axillary staging
Characteristic | Whole cohort [cases (%)] | Matched cohort [cases (%)] | ||||
|---|---|---|---|---|---|---|
Non-staging group | Staging group | P | Non-staging group | Staging group | P | |
Total | 6474 | 160,141 | Â | 5561 | 5561 | Â |
Diagnosis year |  |  | < 0.001 |  |  | 0.871 |
 2000–2003 | 2779 (42.9) | 47,508 (29.7) |  | 2362 (42.5) | 2364 (42.5) |  |
 2004–2008 | 2054 (31.7) | 61,515 (38.4) | 1759 (31.6) | 1737 (31.2) | ||
 2009–2012 | 1641 (25.3) | 51,118 (31.9) | 1440 (25.9) | 1460 (26.3) | ||
Race |  |  | < 0.001 |  |  | 0.423 |
 NHW | 5130 (79.2) | 124,187 (77.5) |  | 4669 (84.0) | 4601 (82.7) |  |
 NHB | 528 (8.2) | 11,880 (7.4) | 353 (6.3) | 353 (6.3) | ||
 NHAIAN | 22 (0.3) | 681 (0.4) | 7 (0.1) | 9 (0.2) | ||
 NHAPI | 342 (5.3) | 10,660 (6.7) | 227 (4.1) | 260 (4.7) | ||
 Hispanic | 430 (6.6) | 12,286 (7.7) | 301 (5.4) | 335 (6.0) | ||
 Unknown | 22 (0.3) | 447 (0.3) | 4 (0.1) | 3 (0.1) | ||
Marital status |  |  | < 0.001 |  |  | 0.236 |
 Married | 3089 (47.7) | 99,060 (61.9) |  | 2823 (50.8) | 2738 (49.2) |  |
 Never married | 639 (9.9) | 17,685 (11.0) | 474 (8.5) | 491 (8.8) | ||
 Widowed | 1856 (28.7) | 19,817 (12.4) | 1617 (29.1) | 1612 (29.0) | ||
 Divorced | 630 (9.7) | 18,539 (11.6) | 480 (8.6) | 531 (9.5) | ||
 Unknown | 260 (4.0) | 5040 (3.1) | 167 (3.0) | 189 (3.4) | ||
Age (years) |  |  | < 0.001 |  |  | 0.525 |
 18–49 | 530 (8.2) | 31,434 (19.6) |  | 435 (7.8) | 478 (8.6) |  |
 50–64 | 1623 (25.1) | 69,378 (43.3) | 1432 (25.8) | 1394 (25.1) | ||
 65–79 | 2596 (40.1) | 51,559 (32.2) | 2299 (41.3) | 2285 (41.1) | ||
 80– | 1725 (26.6) | 7770 (4.9) | 1395 (25.1) | 1404 (25.2) | ||
T stage | Â | Â | <0.001 | Â | Â | 0.905 |
 T1mic | 667 (10.3) | 3778 (2.4) |  | 423 (7.6) | 420 (7.6) |  |
 T1a | 1328 (20.5) | 16,354 (10.2) | 1105 (19.9) | 1121 (20.2) | ||
 T1b | 2020 (31.2) | 50,343 (31.4) | 1804 (32.4) | 1827 (32.9) | ||
 T1c | 2459 (38.0) | 89,666 (56.0) | 2229 (40.1) | 2193 (39.4) | ||
N stage | Â | Â | NA | Â | Â | NA |
 N0 | NA | 134,137 (83.8) |  | NA | 4977 (89.5) |  |
 N1 | NA | 22,617 (14.1) | NA | 527 (9.5) | ||
 N2 | NA | 2552 (1.6) | NA | 44 (0.8) | ||
 N3 | NA | 835 (0.5) | NA | 13 (0.2) | ||
Histological type | Â | Â | <0.001 | Â | Â | 0.330 |
 Ductal | 4616 (71.3) | 122,938 (76.8) |  | 4149 (74.6) | 4079 (73.4) |  |
 Lobular | 1030 (15.9) | 26,723 (16.7) | 850 (15.3) | 919 (16.5) | ||
 Favorable | 676 (10.4) | 8284 (5.2) | 504 (9.1) | 501 (9.0) | ||
 Others | 152 (2.3) | 2196 (1.4) | 58 (1.0) | 62 (1.1) | ||
Grade |  |  | < 0.001 |  |  | 0.911 |
 I | 2180 (33.7) | 48,713 (30.4) |  | 1934 (34.8) | 1965 (35.3) |  |
 II | 2505 (38.7) | 68,905 (43.0) | 2270 (40.8) | 2263 (40.7) | ||
 III | 1048 (16.2) | 35,381 (22.1) | 863 (15.5) | 853 (15.4) | ||
 Unknown | 741 (11.4) | 7142 (4.5) | 494 (8.9) | 480 (8.6) | ||
ER |  |  | < 0.001 |  |  | 0.776 |
 Negative | 678 (10.5) | 20,623 (12.9) |  | 518 (9.3) | 540 (9.7) |  |
 Positive | 5006 (77.3) | 132,246 (82.6) | 4511 (81.1) | 4492 (80.8) | ||
 Unknown | 790 (12.2) | 7272 (4.5) | 532 (9.6) | 529 (9.5) | ||
PR |  |  | < 0.001 |  |  | 0.861 |
 Negative | 1357 (21.0) | 36,191 (22.6) |  | 1087 (19.5) | 1107 (19.9) |  |
 Positive | 4211 (65.0) | 114,492 (71.5) | 3881 (69.8) | 3855 (69.3) | ||
 Unknown | 906 (14.0) | 9458 (5.9) | 593 (10.7) | 599 (10.8) | ||
Chemotherapy |  |  | < 0.001 |  |  | 0.246 |
 No | 5947 (91.9) | 112,270 (70.1) |  | 5109 (91.9) | 5075 (91.3) |  |
 Yes | 527 (8.1) | 47,871 (29.9) | 452 (8.1) | 486 (8.7) | ||