Characteristics | Training Cohort (n = 501) | Validation cohort (n = 303) | P value | ||
---|---|---|---|---|---|
Age (years) | |||||
 Median (IQR) | 52 | (45–64) | 52 | (45–63) | 0.971 |
Clinical tumor size, n (%) | 0.086 | ||||
 ≦1 cm | 40 | (8.0) | 20 | (6.6) | |
 1–2 cm | 184 | (36.7) | 109 | (36.0) | |
 2–3 cm | 177 | (35.3) | 106 | (35.0) | |
 3–4 cm | 48 | (9.6) | 33 | (10.9) | |
 4–5 cm | 37 | (7.4) | 14 | (4.6) | |
 > 5 cm | 15 | (3.0) | 21 | (6.9) | |
Histologic grade, n (%) | 0.577 | ||||
 1 | 107 | (21.4) | 66 | (21.8) | |
 2 | 254 | (50.7) | 143 | (47.2) | |
 3 | 140 | (27.9) | 94 | (31.0) | |
Histologic type, n (%) | 0.615 | ||||
 IC-NST | 420 | (83.8) | 254 | (83.8) | |
 ILC | 53 | (10.6) | 30 | (9.9) | |
 IMPC | 15 | (3.0) | 6 | (2.0) | |
 Others | 13 | (2.6) | 13 | (4.3) | |
Ki-67, n (%) | 0.721 | ||||
 ≤ 10% | 80 | (16.0) | 46 | (15.2) | |
 10–30% | 214 | (42.7) | 121 | (39.9) | |
 ≥ 30% | 145 | (28.9) | 94 | (31.0) | |
 Unknown | 62 | (12.4) | 42 | (13.9) | |
Subtype, n (%) | 0.465 | ||||
 HR+/HER2− | 407 | (81.2) | 237 | (78.2) | |
 HR+/HER2+ | 45 | (9.0) | 32 | (10.6) | |
 HR−/HER2+ | 14 | (2.8) | 14 | (4.6) | |
 HR−/HER2- | 35 | (7.0) | 20 | (6.6) | |
Breast surgery, n (%) | 0.794 | ||||
 Total mastectomy | 299 | (59.7) | 178 | (58.8) | |
 Breast-conserving surgery | 202 | (40.3) | 125 | (41.3) | |
No. of suspicious ALNs on US imaginga, n (%) | 0.213 | ||||
 0 | 375 | (74.9) | 222 | (73.3) | |
 1 (solitary) | 86 | (17.2) | 46 | (15.2) | |
 ≥ 2 (multiple) | 40 | (8.0) | 35 | (11.6) | |
Size of SLN metastasis, n (%) | 0.301 | ||||
 ITC | 86 | (17.2) | 41 | (13.5) | |
 Micrometastasis | 97 | (19.4) | 55 | (18.2) | |
 Macrometastasis | 318 | (63.5) | 207 | (68.3) | |
Ratio of no. of positive SLNs to total no. of SLNs, n (%) | 0.254 | ||||
 < 0.5 | 244 | (48.7) | 135 | (44.6) | |
 ≥ 0.5 | 257 | (51.3) | 168 | (55.5) | |
Total no. of dissected SLNs | |||||
 Median (IQR) | 3 | (2–4) | 3 | (2–4) | 0.908 |
No. of metastatic SLNs | 0.380 | ||||
 0 (ITC) | 86 | (17.2) | 41 | (13.5) | |
 1 | 297 | (59.3) | 180 | (59.4) | |
 2 | 89 | (17.8) | 58 | (19.1) | |
 3 | 29 | (5.8) | 24 | (7.9) | |
Total no. of dissected ALNs | |||||
 Median (IQR) | 17 | (13–21) | 17 | (13–20) | 0.967 |
Nodal status, n (%) | 0.513 | ||||
 pN0i+ | 78 | (15.6) | 37 | (12.4) | |
 pN1 | 348 | (69.5) | 217 | (71.2) | |
 pN2 | 62 | (12.4) | 38 | (13.0) | |
 pN3 | 13 | (2.6) | 11 | (3.3) |