Patient Population
| Characteristic | Main dataset (n = 301) | Auxiliary dataset (n = 200) |
| Age (y) | ||
| ≤50 | 196 (65) | 125 (63) |
| >50 | 105 (35) | 75 (37) |
| Type of surgery | ||
| Lumpectomy | 255 (85) | 182 (91) |
| Mastectomy | 46 (15) | 18 (9) |
| Pathologic type | ||
| Infiltrating ductal carcinoma | 283 (94) | 192 (97) |
| Infiltrating lobular carcinoma | 3 (1) | 5 (2) |
| Others* | 15 (5) | 3 (1) |
| Primary tumor size (mm) | ||
| ≤5 (pT1mic – pT1a) | 13 (4) | 26 (13) |
| 6–10 (pT1b) | 18 (6) | 35 (17) |
| 11–20 (pT1c) | 106 (35) | 71 (36) |
| 21–50 (pT2) | 158 (53) | 62 (31) |
| >50 (pT3) | 6 (2) | 6 (3) |
| Histologic grade | ||
| I | 12 (4) | 28 (14) |
| II | 173 (57) | 73 (36) |
| III | 116 (39) | 99 (50) |
| No. of negative SLNs | ||
| 0 | 112 (38) | 10 (5) |
| 1 | 95 (32) | 55 (28) |
| 2 | 60 (20) | 76 (38) |
| 3 | 21 (7) | 41 (20) |
| 4 | 4 (1) | 14 (7) |
| 5 | 4 (1) | 3 (2) |
| 6 | 3 (1) | 0 (0) |
| 7 | 1 (0) | 0 (0) |
| 8 | 1 (0) | 1 (0) |
| No. of positive SLNs | Not applicable | |
| 1 | 196 (65) | |
| 2 | 75 (25) | |
| 3 | 21 (7) | |
| 4 | 5 (2) | |
| 5 | 1 (0) | |
| 6 | 2 (1) | |
| 7 | 1 (0) | |
| Size of LN metastasis (mm) | Not applicable | |
| ≤0.2 | 5 (2) | |
| 0.2–2 | 33 (11) | |
| 2–10 | 189 (63) | |
| 10–20 | 62 (21) | |
| >20 | 12 (4) | |
| Lymphovascular invasion | ||
| Present | 10 (3) | 132 (66) |
| Absent | 291 (97) | 68 (34) |
| Multifocality | ||
| Yes | 31 (10) | 25 (12) |
| No | 270 (90) | 175 (88) |
| Estrogen receptor status | ||
| Positive | 244 (81) | 139 (70) |
| Negative | 57 (19) | 61 (30) |
| Progesterone receptor status | ||
| Positive | 239 (79) | 156 (78) |
| Negative | 62 (21) | 44 (22) |
| HER2/neu status | ||
| Positive | 39 (13) | 25 (13) |
| Negative | 191 (63) | 95 (47) |
| Unknown† | 71 (24) | 80 (40) |