Table 2.
Treatment characteristics
| Characteristic | Initial RT | Re-RT |
|---|---|---|
| RT modality | ||
| 2D-RT | 11 (18.3) | 0 |
| 3D-CRT | 20 (33.3) | 20 (33.3) |
| IMRT | 29 (48.3) | 33a) (55.0) |
| IMPTb) | 0 | 7 (11.7) |
| RT fraction size (range) | ||
| 1.8 Gy | 24 (40.0) | 0 |
| 2.0 Gy | 18 (30.0) | 0 |
| 2.15–2.46 Gy | 18 (30.0) | 4 (6.7) |
| 2.5 Gy | 0 | 24 (40.0) |
| 3.0 Gy | 0 | 29 (48.3) |
| 3.2–4.0 Gy | 0 | 3 (5.0) |
| Median (range, Gy) | 2.0 (1.8–2.5) | 3.0 (2.3–4.0) |
| Total RT dose | ||
| BED10 (Gy) | 84.0 (57.6–107.2) | 78.0 (56.0–87.5) |
| BED3 (Gy) | 116.7 (80.0–156.5) | 120.0 (91.7–132.3) |
| Median (Gy) | 70.0 (48.0–86.0) | 60.0 (40.0–70.0) |
| Cumulated RT dose | ||
| BED10 (Gy) | 160.2 (135.6–194.7) | |
| BED3 (Gy) | 230.1 (200.0–284.9) | |
| Additional chemotherapy | ||
| Not done | 7 (11.7) | 47 (78.4) |
| Induction chemotherapy | 12 (20.0) | 5 (8.3) |
| Concurrent chemotherapy | 41 (68.3) | 8 (13.3) |
Values are presented as number (%) or median (range). 2D/3D, 2-/3-dimensional; BED3, biologically equivalent dose, α/β ratio=3; BED10, biologically equivalent dose, α/β ratio=10; CRT, conformal radiation therapy; IMPT, intensity modulated proton therapy; IMRT, intensitymodulated radiation therapy; RT, radiation therapy.
a)
Five patients were treated with proton boost following IMRT,
b)
Relative biologic effectiveness (RBE) of 1.1 for proton therapy.