Table 1.
Patient characteristics of the training and validation cohorts
| Variable | Total (n = 457) | Training (n = 285) | Validation (n = 172) | P Value |
|---|---|---|---|---|
| Age (years) | 63 (39–80) | 61 (391–76) | 64 (44–80) | <0.001 |
| Sex | 0.582 | |||
| Male | 425 (93.0%) | 267 (93.7%) | 158 (91.9%) | – |
| Female | 32 (7.0%) | 18 (6.3%) | 14 (8.1%) | – |
| ECOG PS | 0.059 | |||
| 0 | 97 (21.2%) | 69 (24.2%) | 28 (16.3%) | – |
| 1 | 360 (78.8%) | 216 (75.8%) | 144 (83.7%) | – |
| Charlson–Deyo score | 0.277 | |||
| 0 | 352 (77.0%) | 211 (74.0%) | 141 (82.0%) | – |
| 1 | 84 (18.4%) | 59 (20.7%) | 25 (14.5%) | – |
| 2 | 17 (3.7%) | 12 (4.2%) | 5 (2.9%) | – |
| 3 | 4 (0.9%) | 3 (1.1%) | 1 (0.6%) | – |
| Alcohol consumption | 0.953 | |||
| No | 55 (12.0%) | 35 (12.3%) | 20 (11.6%) | – |
| Yes | 402 (88.0%) | 250 (87.7%) | 152 (88.4%) | – |
| Smoking history | 0.879 | |||
| No | 88 (19.3%) | 56 (19.6%) | 32 (18.6%) | – |
| Yes | 369 (80.7%) | 229 (80.4%) | 140 (81.4%) | – |
| Histologic grade | 0.576 | |||
| Well-differentiated | 57 (12.9%) | 35 (12.8%) | 22 (13.2%) | |
| Moderately differentiated | 337 (76.4%) | 213 (77.7%) | 124 (74.3%) | |
| Poorly differentiated | 47 (10.7%) | 26 (9.5%) | 21 (12.6%) | |
| Clinical T stage | 0.103 | |||
| 1–2 | 180 (39.4%) | 77 (27.0%) | 24 (14.0%) | – |
| 3–4 | 277 (60.6%) | 208 (73.0%) | 148 (86.0%) | – |
| Clinical N stage | <0.001 | |||
| N0 | 176 (38.5%) | 137 (48.1%) | 39 (22.7%) | – |
| N+ | 281 (61.5%) | 148 (51.9%) | 133 (77.3%) | – |
| Initial mSUV | 12.5 (1.3–38.0) | 11.0 (1.3–34.9) | 14.3 (1.3–38.0) | <0.001 |
| Induction chemotherapy | <0.001 | |||
| None | 82 (17.9%) | 34 (11.9%) | 48 (27.9%) | – |
| Yes | 375 (82.1%) | 251 (88.1%) | 124 (72.1%) | – |
| Chemotherapy regimen | 0.044 | |||
| XP/FP | 376 (82.3%) | 226 (79.3%) | 150 (87.2%) | |
| Others | 81 (17.7%) | 59 (20.7%) | 22 (12.8%) | |
| RT dose (Gy) | 46.0 (38.0–50.4) | 46.0 (38.0–50.4) | 50.0 (40.0–50.4) | <0.001 |
| Post-PCRT endoscopy | 0.262 | |||
| CR | 138 (30.3%) | 80 (28.3%) | 58 (33.7%) | – |
| Non-CR | 317 (69.7%) | 203 (71.7%) | 114 (66.3%) | – |
| Post-PCRT biopsy | 0.969 | |||
| CR | 380 (83.5%) | 237 (83.7%) | 143 (83.1%) | – |
| Non-CR | 75 (16.5%) | 46 (16.3%) | 29 (16.9%) | – |
| Post-CCRT mSUV | 3.4 (1.2–22.0) | 3.1 (1.3–22.0) | 4.3 (1.2–18.2) | <0.001 |
| ΔmSUV (%) | 68.2 (−607–94.4) | 68.8 (−607–94.4) | 67.5 (−453–93.8) | 0.719 |
| Pathologic response | 0.457 | |||
| CR | 209 (45.7%) | 126 (44.2%) | 83 (48.3%) | – |
| Non-CR | 248 (54.3%) | 159 (55.8%) | 89 (51.7%) | – |
ECOG PS = Eastern Cooperative Oncology Group performance status, mSUV = maximum standardized uptake value, XP = capecitabine plus cisplatin, FP = 5-fluorouracil plus cisplatin, RT = radiotherapy, PCRT = preoperative chemoradiotherapy, CR = complete response.