Table 1 Clinical and pathological characteristics of patients from the training and validation sets
| Â | Training | Validation |
|---|---|---|
Characteristics | n = 142 | n = 279 |
| Â | n (%) | n (%) |
Age | Â | Â |
   <40 | 9 (6.4) | 20 (7.2) |
   40 – 49 | 18 (12.8) | 74 (26.5) |
   50 – 59 | 28 (19.9) | 77 (27.6) |
   60 – 69 | 48 (34.0) | 73 (26.2) |
   ≥ 70 | 38 (27.0) | 35 (12.5) |
   Missing | 1 | 0 |
   Median | 64 yrs (SD 12.6) | 55 yrs (SD 11.7) |
   Min. – Max. | 31 – 89 yrs | 29 – 87 yrs |
Tumor diameter | Â | Â |
   ≤ 2 cm | 126 (94.0) | 168 (60.2) |
   > 2 cm | 8 (6.0) | 111 (39.8) |
   Missing | 8 | 0 |
   Median | 1.2 cm (SD 0.50) | 2 cm (SD 0.85) |
   Min. – Max. | 0.3 – 2.9 cm | 0.0* – 3.0 cm |
Tumor grade | Â | Â |
   Grade 1 | 74 (53.2) | 60 (21.5) |
   Grade 2 | 61 (43.9) | 166 (59.5) |
   Grade 3 | 4 (2.9) | 53 (19.0) |
   Missing | 3 | 0 |
Stage | Â | Â |
   I | 126 (94.0) | 168 (60.2) |
   IIA | 8 (6.0) | 111 (39.8) |
   Missing | 8 | 0 |
HER2 | Â | Â |
   Negative | na | 251 (93.0) |
   Positive | na | 19 (7.0) |
   Missing |  | 9 |
Surgery | Â | Â |
   Breast conserving | na | 112 (40.1) |
   Mastectomy | na | 167 (59.9) |
Radiotherapy | Â | Â |
   Yes | na | 115 (39.7) |
   No | na | 175 (60.3) |
Distant recurrence | Â | Â |
   Yes | 31 (21.8) | 71 (25.5) |
   No | 111 (78.2) | 208 (74.6) |
Death of all cause | Â | Â |
   Yes | 56 (39.4) | 134 (48.0) |
   No | 86 (60.6) | 145 (52.0) |
Median follow up | 8.7 yrs | 15.6 yrs |