Table 1.
Clinicopathologic characteristics between axillary lymph node positive and negative groups in the training, prospective-retrospective validation and external validation cohorts.
| Training cohort | Prospective-retrospective validation cohort | External validation cohort | ||||
|---|---|---|---|---|---|---|
| (No. of patients[n] = 803) | (n =106) | (n =179) | ||||
| Axillary lymph node status | Axillary lymph node status | Axillary lymph node status | ||||
| Characteristic | Negative | Positive | Negative | Positive | Negative | Positive |
| (n = 475) | (n = 328) | (n = 28) | (n = 78) | (n = 94) | (n = 85) | |
| Age, years (median [IQR]) | 48 [43,56] | 48 [41,56] | 42 [39,46] | 41 [38,45] | 49 [43,56] | 46 [42,56] |
| Number of tumors (%) | ||||||
| 1 | 421 (88·6) | 284 (86·9) | 21 (75·0) | 62 (79·5) | 76 (80·9) | 72 (84·7) |
| >1 | 54 (11·4) | 43 (13·1) | 7 (25·0) | 16 (20·5) | 18 (19·1) | 13 (15·3) |
| Tumor size, cm (median [IQR]) | 2·0 [1·6, 2·7] | 2·5 [2·0, 3·2] | 3·6 [2·6, 5·0] | 3·1 [2·5, 5·1] | 2·3 [1·7, 2·8] | 2·8 [2·1, 3·7] |
| Clinical T stage (%) | ||||||
| T1 | 241 (50·7) | 97 (29·6) | 0 (0·0) | 12 (15·4) | 39 (41·5) | 18 (21·2) |
| T2 | 213 (44·8) | 209 (63·7) | 22 (78·6) | 44 (56·4) | 50 (53·2) | 58 (68·2) |
| T3 | 16 (3·4) | 15 (4·6) | 4 (14·3) | 18 (23·1) | 3 (3·2) | 7 (8·2) |
| T4 | 5 (1·1) | 7 (2·1) | 2 (7·1) | 4 (5·1) | 2 (2·1) | 2 (2·4) |
| Clinical N stage (%) | ||||||
| N0 | 382 (80·4) | 132 (40·2) | 15 (60·0) | 21 (29·6) | 85 (96·6) | 37 (50·0) |
| N1 | 90 (18·9) | 178 (54·3) | 10 (40·0) | 45 (63·4) | 3 (3·4) | 20 (27·0) |
| N2 | 2 (0·4) | 18 (5·5) | 0 (0·0) | 4 (5·6) | 0 (0·0) | 16 (21·6) |
| N3 | 1 (0·2) | 0 (0·0) | 0 (0·0) | 1 (1·4) | 0 (0·0) | 1 (1·4) |
| Clinical TNM stage (%) | ||||||
| I | 207 (43·6) | 51 (15·5) | 0 (0·0) | 4 (5·6) | 37 (42·0) | 12 (16·2) |
| II | 253 (53·3) | 241 (73·5) | 22 (88·0) | 51 (71·8) | 48 (54·5) | 42 (56·8) |
| III | 15 (3·2) | 36 (11·0) | 3 (12·0) | 16 (22·5) | 3 (3·4) | 20 (27·0) |
| Histological grade (%) | ||||||
| Grade 1 (low) | 22 (5·0) | 2 (0·6) | 0 (0·0) | 0 (0·0) | 4 (4·9) | 5 (6·7) |
| Grade 2 (intermediate) | 235 (53·0) | 149 (46·1) | 10 (50·0) | 43 (72·9) | 46 (56·1) | 33 (44·0) |
| Grade 3 (high) | 186 (42·0) | 172 (53·3) | 10 (50·0) | 16 (27·1) | 32 (39·0) | 37 (49·3) |
| Pathologic T stage (%) | ||||||
| T1 | 272 (57·3) | 140 (42·7) | 19 (67·9) | 30 (40·0) | 45 (47·9) | 23 (27·1) |
| T2 | 188 (39·6) | 171 (52·1) | 7 (25·0) | 32 (42·7) | 45 (47·9) | 55 (64·7) |
| T3 | 13 (2·7) | 16 (4·9) | 1 (3·6) | 7 (9·3) | 2 (2·1) | 6 (7·1) |
| T4 | 2 (0·4) | 1 (0·3) | 1 (3·6) | 6 (8·0) | 2 (2·1) | 1 (1·2) |
| Pathologic TNM stage (%) | ||||||
| I | 271 (57·1) | 0 (0·0) | 19 (67·9) | 0 (0·0) | 45 (47·9) | 0 (0·0) |
| II | 202 (42·5) | 206 (62·8) | 8 (28·6) | 28 (37·3) | 47 (50·0) | 44 (51·8) |
| III | 2 (0·4) | 122 (37·2) | 1 (3·6) | 47 (62·7) | 2 (2·1) | 41 (48·2) |
| ER status (%) | ||||||
| Negative | 64 (13·6) | 51 (15·5) | 5 (17·9) | 8 (10·3) | 20 (21·3) | 25 (29·8) |
| Positive | 407 (86·4) | 277 (84·5) | 23 (82·1) | 70 (89·7) | 74 (78·7) | 59 (70·2) |
| PR status (%) | ||||||
| Negative | 128 (27·2) | 91 (27·7) | 14 (50·0) | 23 (29·5) | 31 (33·0) | 29 (34·5) |
| Positive | 343 (72·8) | 237 (72·3) | 14 (50·0) | 55 (70·5) | 63 (67·0) | 55 (65·5) |
| HER2 status (%) | ||||||
| Negative | 326 (72·0) | 208 (65·4) | 15 (68·2) | 43 (65·2) | 59 (71·1) | 44 (62·9) |
| Positive | 127 (28·0) | 110 (34·6) | 7 (31·8) | 23 (34·8) | 24 (28·9) | 26 (37·1) |
| Ki67 status (%) | ||||||
| <30 | 259 (55·0) | 150 (45·7) | 12 (42·9) | 63 (80·8) | 52 (57·1) | 49 (59·8) |
| ≥30 | 212 (45·0) | 178 (54·3) | 16 (57·1) | 15 (19·2) | 39 (42·9) | 33 (40·2) |
| Molecular subtypes (%) | ||||||
| Luminal A | 92 (20·0) | 30 (9·2) | 4 (16·0) | 21 (30·0) | 20 (23·0) | 15 (19·7) |
| Luminal B | 306 (66·7) | 249 (76·6) | 16 (64·0) | 42 (60·0) | 50 (57·5) | 40 (52·6) |
| HER2-positive | 31 (6·8) | 28 (8·6) | 1 (4·0) | 3 (4·3) | 6 (6·9) | 12 (15·8) |
| Triple negative | 30 (6·5) | 18 (5·5) | 4 (16·0) | 4 (5·7) | 11 (12·6) | 9 (11·8) |
| Type of surgery (%) | ||||||
| Breast-conserving surgery | 250 (52·7) | 127 (38·7) | 14 (50·0) | 28 (35·9) | 22 (23·4) | 18 (21·2) |
| Others | 224 (47·3) | 201 (61·3) | 14 (50·0) | 50 (64·1) | 72 (76·6) | 67 (78·8) |
| Follow-up time, months (median [IQR]) | 23·4 [15·8, 35·6] | 21·7 [15·3, 35·1] | 45·5 [21·5, 65·2] | 44·6 [25·5, 57·1] | 22·6 [10·6, 41·5] | 24·3 [9·4, 55·1] |
IQR=interquartile range. TNM=tumor–node–metastasis. ER=estrogen receptor. PR=progesterone receptor. HER2=human epidermal growth factor receptor 2. Ki67=proliferation marker protein Ki67.