Table 1 Clinical characteristics and magnetic resonance imaging features of patients
Characteristics | Training set (n = 311) | Internal testing set (n = 169) | External testing set (n = 163) | P value |
|---|---|---|---|---|
Age, years* | 47.32 [23.00–76.00] | 48.59 [27.00–80.00] | 49.90 [30.00–77.00] | 0.040 |
Menopausal status | Â | Â | Â | 0.062 |
 Pre-menopause | 218 (70.10%) | 109 (64.50%) | 97 (59.51%) |  |
 Post-menopause | 93 (29.90%) | 60 (35.50%) | 66 (40.49%) |  |
Risk factors | Â | Â | Â | 0.037 |
 No | 285 (91.64%) | 155 (91.72%) | 159 (97.55%) |  |
 Yes | 26 (8.36%) | 14 (8.28%) | 4 (2.45%) |  |
Pathologic tumor size (cm) * | 2.09 [0.30–7.00] | 2.27 [0.40–6.60] | 2.35 [0.60–6.00] | 0.008 |
ER | Â | Â | Â | 0.998 |
 Negative | 67 (21.54%) | 36 (21.30%) | 35 (21.47%) |  |
 Positive | 244 (78.46%) | 133 (78.70%) | 128 (78.53%) |  |
PR | Â | Â | Â | 0.825 |
 Negative | 93 (29.90%) | 46 (27.22%) | 47 (28.83%) |  |
 Positive | 218 (70.10%) | 123 (72.78%) | 116 (71.17%) |  |
HER2 | Â | Â | Â | 0.927 |
 Negative | 232 (74.60%) | 128 (75.74%) | 124 (76.07%) |  |
 Positive | 79 (25.40%) | 41 (24.26%) | 39 (23.93%) |  |
Ki-67 | Â | Â | Â | 0.353 |
 Low | 81 (26.05%) | 43 (25.44%) | 33 (20.25%) |  |
 High | 230 (73.95%) | 126 (74.56%) | 130 (79.75%) |  |
Molecular subtype | Â | Â | Â | 0.761 |
 Luminal A | 69 (22.19%) | 39 (23.08%) | 30 (18.40%) |  |
 Luminal B | 180 (57.88%) | 98 (57.99%) | 99 (60.74%) |  |
 HER2-enriched | 27 (8.68%) | 9 (5.33%) | 13 (7.98%) |  |
 Triple-negative | 35 (11.25%) | 23 (13.61%) | 21 (12.88%) |  |
T stage | Â | Â | Â | 0.563 |
 1 | 183 (58.84%) | 94 (55.62%) | 88 (53.99%) |  |
 2 | 120 (38.59%) | 71 (42.01%) | 72 (44.17%) |  |
 3 or 4 | 8 (2.57%) | 4 (2.37%) | 3 (1.84%) |  |
N stage | Â | Â | Â | 0.456 |
 0 | 193 (62.06%) | 113 (66.86%) | 101 (61.96%) |  |
 1 | 76 (24.44%) | 37 (21.89%) | 42 (25.77%) |  |
 2 | 29 (9.32%) | 14 (8.28%) | 9 (5.52%) |  |
 3 | 13 (4.18%) | 5 (2.96%) | 11 (6.75%) |  |
TNM stage | Â | Â | Â | 0.627 |
 I | 133 (42.77%) | 64 (37.87%) | 62 (38.04%) |  |
 II | 133 (42.77%) | 84 (49.70%) | 78 (47.85%) |  |
 III | 45 (14.47%) | 21 (12.43%) | 23 (14.11%) |  |
Lymphovascular invasion | Â | Â | Â | 0.022 |
 Absent | 211 (67.85%) | 119 (70.41%) | 130 (79.75%) |  |
 Present | 100 (32.15%) | 50 (29.59%) | 33 (20.25%) |  |
Associated ductal carcinoma in situ |  |  |  | < 0.0001 |
 Absent | 200 (64.31%) | 118 (69.82%) | 136 (83.44%) |  |
 Present | 111 (35.69%) | 51 (30.18%) | 27 (16.56%) |  |
Histological type | Â | Â | Â | 0.584 |
 invasive ductal carcinoma | 284 (91.32%) | 154 (91.12%) | 154 (94.48%) |  |
 invasive lobular carcinoma | 12 (3.86%) | 6 (3.55%) | 2 (1.23%) |  |
 Others invasive breast cancer | 15 (4.82%) | 9 (5.33%) | 7 (4.29%) |  |
Histological grade | Â | Â | Â | 0.0002 |
 I or II | 175 (56.27%) | 94 (55.62%) | 123 (75.46%) |  |
 III | 112 (36.01%) | 60 (35.50%) | 27 (16.56%) |  |
 Missing | 24 (7.72%) | 15 (8.88%) | 13 (7.98%) |  |
Surgery type | Â | Â | Â | 0.795 |
 Mastectomy | 192 (61.74%) | 100 (59.17%) | 102 (62.58%) |  |
 Breast conservation | 119 (38.26%) | 69 (40.83%) | 61 (37.42%) |  |
Adjuvant endocrine therapy | Â | Â | Â | 0.828 |
 No | 85 (27.33%) | 42 (24.82%) | 42 (25.77%) |  |
 Yes | 226 (72.67%) | 127 (75.15%) | 121 (74.23%) |  |
Adjuvant chemotherapy | Â | Â | Â | 0.0002 |
 No | 72 (23.15%) | 44 (26.04%) | 15 (9.20%) |  |
 Yes | 239 (76.85%) | 125 (73.96%) | 148 (90.80%) |  |
Adjuvant radiotherapy | Â | Â | Â | 0.823 |
 No | 149 (47.91%) | 86 (50.89%) | 80 (49.08%) |  |
 Yes | 162 (52.09%) | 83 (49.11%) | 83 (50.92%) |  |
Adjuvant targeted therapy | Â | Â | Â | 0.096 |
 No | 256 (82.32%) | 146 (86.39%) | 126 (77.30%) |  |
 Yes | 55 (17.68%) | 23 (13.61%) | 37 (22.70%) |  |
MR tumor size (cm) * | 2.18 [0.70–6.00] | 2.36 [0.70–7.20] | 2.31 [0.90–5.90] | 0.119 |
Time-signal intensity curve | Â | Â | Â | 0.132 |
 Persistent | 17 (5.47%) | 4 (2.37%) | 6 (3.68%) |  |
 Plateau | 181 (58.20%) | 106 (62.72%) | 112 (68.71%) |  |
 Washout | 113 (36.33%) | 59 (34.91%) | 45 (27.61%) |  |
Shape | Â | Â | Â | 0.008 |
 Oval or Round | 86 (27.65%) | 55 (32.54%) | 29 (17.79%) |  |
 Irregular | 225 (72.35%) | 114 (67.46%) | 134 (82.21%) |  |
Margin | Â | Â | Â | 0.717 |
 Circumscribed | 36 (11.58%) | 21 (12.43%) | 24 (14.72%) |  |
 Irregular | 154 (49.52%) | 77 (45.56%) | 71 (43.56%) |  |
 Spiculated | 121 (38.91%) | 71 (42.01%) | 68 (41.72%) |  |
Internal enhancement | Â | Â | Â | 0.061 |
 Homogeneous | 6 (1.93%) | 4 (2.37%) | 2 (1.23%) |  |
 Heterogeneous | 218 (70.10%) | 108 (63.91%) | 125 (76.69%) |  |
 Rim enhancement | 87 (27.97%) | 57 (33.73%) | 36 (22.09%) |  |
Disease-free survival events | Â | Â | Â | 0.974 |
 No | 275 (88.42%) | 149 (88.17%) | 145 (88.96%) |  |
 Yes | 36 (11.58%) | 20 (11.83%) | 18 (11.04%) |  |
Follow-up time (months) * | 61.48 [1.57-138.27] | 61.36 [5.47–138.10] | 47.63 [7.97–75.97] | < 0.0001 |