Table 1 Clinicopathologic characteristics of all patients
|  | Low risk (N = 8614) | High risk (N = 4493) | p value |
|---|---|---|---|
Age | 52.0 [47.0;60.0] | 41.0 [37.0;51.0] | < 0.001 |
Location | Â | Â | 0.306 |
 Right | 4212 (48.9%) | 2240 (49.9%) |  |
 Left | 4402 (51.1%) | 2253 (50.1%) |  |
Breast surgery |  |  | < 0.001 |
 Breast conserving surgery | 5297 (61.5%) | 3002 (66.8%) |  |
 Mastectomy | 3317 (38.5%) | 1491 (33.2%) |  |
Axilla surgery |  |  | < 0.001 |
 Sentinel LN biopsy | 5255 (61.0%) | 2576 (57.3%) |  |
 Axilla LN dissection | 3111 (36.1%) | 1820 (40.5%) |  |
 Not done | 49 (0.6%) | 12 (0.3%) |  |
 Unknown | 199 (2.3%) | 85 (1.9%) |  |
T stage |  |  | < 0.001 |
 T1 | 4477 (52.0%) | 1898 (42.2%) |  |
 T2 | 3447 (40.0%) | 2138 (47.6%) |  |
 T3 | 485 (5.6%) | 321 (7.1%) |  |
 T4 | 198 (2.3%) | 126 (2.8%) |  |
N stage |  |  | < 0.001 |
 N0 | 5100 (59.2%) | 2478 (55.2%) |  |
 N1 | 2245 (26.1%) | 1236 (27.5%) |  |
 N2 | 834 (9.7%) | 511 (11.4%) |  |
 N3 | 391 (4.5%) | 247 (5.5%) |  |
Subtype |  |  | < 0.001 |
 Hormone receptor+/HER2− | 6181 (71.8%) | 2020 (45.0%) |  |
 Hormone receptor+/HER2+ | 965 (11.2%) | 406 (9.0%) |  |
 Hormone receptor−/HER2+ | 1114 (12.9%) | 263 (5.9%) |  |
 Hormone receptor−/HER2− | 354 (4.1%) | 1804 (40.2%) |  |
Histologic grade |  |  | < 0.001 |
 1 | 936 (10.9%) | 253 (5.6%) |  |
 2 | 4477 (52.0%) | 1712 (38.1%) |  |
 3 | 2745 (31.9%) | 2239 (49.8%) |  |
 Unknown | 456 (5.3%) | 289 (6.4%) |  |
Lymphovascular invasion |  |  | < 0.001 |
 Present | 2388 (27.7%) | 1409 (31.4%) |  |
 None | 5933 (68.9%) | 2886 (64.2%) |  |
 Unknown | 293 (3.4%) | 198 (4.4%) |  |