Table 3. Subgroup analyses of locoregional control and overall survival.
| Characteristics | Locoregional control (%) | P value | Overall survival (%) | P value | ||||
|---|---|---|---|---|---|---|---|---|
| 1 year | 2 years | 3 years | 1 year | 2 years | 3 years | |||
| Cervical/upper esophagus | 0.421 | |||||||
| C-IMRT | 85.2 | 56.3 | 56.3 | 0.160 | 82.5 | 53.2 | 53.2 | |
| SIR-IMRT | 75.9 | 52.9 | 40.8 | 85.4 | 56.7 | 28.8 | ||
| Middle/lower esophagus | 0.586 | |||||||
| C-IMRT | 75.2 | 46.5 | 46.5 | 0.710 | 62.8 | 35.7 | 35.7 | |
| SIR-IMRT | 82.4 | 57.0 | 42.3 | 74.4 | 48.4 | 31.4 | ||
| Early stage (II) | 0.941 | |||||||
| C-IMRT | 86.7 | 74.8 | 49.9 | 0.768 | 76.0 | 61.9 | 61.9 | |
| SIR-IMRT | 95.5 | 53.0 | 39.8 | 95.5 | 44.7 | 33.6 | ||
| Advanced stage (III–IV) | 0.751 | |||||||
| C-IMRT | 79.3 | 56.4 | 56.4 | 0.213 | 70.2 | 40.0 | 40.0 | |
| SIR-IMRT | 75.6 | 57.0 | 42.1 | 72.7 | 53.9 | 32.0 | ||
| AJCC T2 stage | 0.189 | |||||||
| C-IMRT | 87.5 | 70.0 | 70.0 | 0.991 | 70.0 | 56.0 | 56.0 | |
| SIR-IMRT | 100.0 | 83.3 | 66.7 | 100.0 | 83.3 | 66.7 | ||
| AJCC T3–T4 stage | 0.386 | |||||||
| C-IMRT | 80.2 | 59.4 | 54.5 | 0.191 | 71.6 | 43.4 | 43.4 | |
| SIR-IMRT | 77.8 | 52.6 | 37.5 | 74.9 | 47.5 | 26.5 | ||
| AJCC N0 stage | 0.596 | |||||||
| C-IMRT | 75.6 | 64.6 | 55.6 | 0.910 | 66.2 | 55.0 | 55.0 | |
| SIR-IMRT | 87.9 | 61.2 | 43.7 | 86.5 | 53.9 | 38.5 | ||
| AJCC N1 stage | 0.556 | |||||||
| C-IMRT | 85.2 | 56.3 | 56.3 | 0.160 | 75.8 | 36.9 | 36.9 | |
| SIR-IMRT | 75.9 | 52.9 | 40.8 | 72.7 | 51.0 | 29.2 | ||
| Tumor length ≤5 cm | 0.421 | |||||||
| C-IMRT | 85.2 | 56.3 | 56.3 | 0.160 | 82.5 | 53.2 | 53.2 | |
| SIR-IMRT | 75.9 | 52.9 | 40.8 | 85.4 | 56.7 | 28.8 | ||
| Tumor length >5 cm | 0.922 | |||||||
| C-IMRT | 73.5 | 48.4 | 45.9 | 0.981 | 63.4 | 38.1 | 38.1 | |
| SIR-IMRT | 73.6 | 49.1 | 49.1 | 70.6 | 46.0 | 34.5 | ||
| GTV volume ≤40 cm3 | 0.275 | |||||||
| C-IMRT | 79.4 | 62.9 | 52.6 | 0.431 | 71.4 | 43.8 | 43.8 | |
| SIR-IMRT | 88.4 | 57.3 | 37.0 | 89.8 | 58.7 | 38.1 | ||
| GTV volume >40 cm3 | 0.069 | |||||||
| C-IMRT | 82.6 | 58.5 | 58.5 | 0.317 | 71.6 | 45.0 | 45.0 | |
| SIR-IMRT | 66.5 | 58.2 | 58.2 | 59.7 | 43.5 | 26.1 | ||
| No chemotherapy | 0.056 | |||||||
| C-IMRT | 76.8 | 70.4 | 70.4 | 0.087 | 66.9 | 44.6 | 44.6 | |
| SIR-IMRT | 76.6 | 34.5 | 23.0 | 51.3 | 33.0 | 11.0 | ||
| Chemotherapy | 0.473 | |||||||
| C-IMRT | 82.7 | 58.8 | 53.5 | 0.566 | 72.3 | 44.4 | 44.4 | |
| SIR-IMRT | 83.3 | 60.6 | 46.0 | 83.1 | 55.4 | 39.0 | ||
| No CCRT | 0.051 | |||||||
| C-IMRT | 78.1 | 64.7 | 64.7 | 0.066 | 70.0 | 40.4 | 40.4 | |
| SIR-IMRT | 67.5 | 36.0 | 24.0 | 60.5 | 37.0 | 9.3 | ||
| CCRT | 0.261 | |||||||
| C-IMRT | 83.7 | 58.3 | 52.6 | 0.692 | 72.1 | 45.7 | 45.7 | |
| SIR-IMRT | 84.7 | 63.7 | 48.4 | 85.7 | 58.8 | 44.9 | ||
SIR-IMRT, simultaneous integrated dose reduction in clinical target volume with intensity-modulated radiotherapy; C-IMRT, conventional-IMRT; AJCC, American Joint Committee Cancer; GTV, gross tumor volume; CCRT, concurrent chemoradiotherapy.