Table 2.
Characteristics at Baseline and Treatment Modalities (N = 206)
| Characteristics | No. of Patients |
|---|---|
| Age, y | |
| Median (range) | 49 (17‐73) |
| <60 | 170 (82.52%) |
| ≥60 | 36 (17.48%) |
| Sex | |
| Female | 53 (25.73%) |
| Male | 153 (74.27%) |
| DFI, mo | |
| Median (range) | 28.6 (4.4‐393.5) |
| <12 | 22 (10.68%) |
| ≥12 | 184 (89.32%) |
| Initial RT technique | |
| IMRT + CIRT a | 1 (0.49%) |
| IMRT | 194 (94.17%) |
| Non‐IMRT | 8 (3.88%) |
| Unknown | 3 (1.46%) |
| Histological classification b | |
| Nonkeratinizing undifferentiated carcinoma | 148 (71.85%) |
| Nonkeratinizing differentiated carcinoma | 26 (12.62%) |
| Squamous cell carcinoma, NOS | 32 (15.53%) |
| Recurrent tumor classification | |
| T0 | 20 (9.71%) |
| T1 | 24 (11.65%) |
| T2 | 26 (12.62%) |
| T3 | 60 (29.13%) |
| T4 | 76 (36.89%) |
| Recurrent lymph node classification | |
| N0 | 140 (67.96%) |
| N1 | 53 (25.73%) |
| N2 | 8 (3.88%) |
| N3 | 5 (2.43%) |
| Recurrent AJCC disease stage | |
| I | 17 (8.25%) |
| II | 50 (24.27%) |
| III | 60 (29.13%) |
| IV c | 79 (38.35%) |
| Median GTV (range), mL | 22.46 (1.72‐201.49) |
| Baseline necrosis | |
| Absent | 153 (74.27%) |
| Present | 53 (25.73%) |
| Salvage CIRT dose to GTV, GyE | |
| Median (range) | 63 (50‐69) |
| <63 | 63 (30.58%) |
| ≥63 | 143 (69.42%) |
| Fractionation, GyE | |
| Median (range) | 3 (2‐3) |
| <3 | 31 (15.05%) |
| 3 | 175 (84.95%) |
| Median BED, GyE | 81.9 (60‐89.7) |
| Chemotherapy | |
| Chemotherapy prior to CIRT | 126 (61.17%) |
| Chemotherapy concurrent with CIRT | 38 (18.45%) |
Abbreviations: AJCC, American Joint Committee on Cancer; BED, biological equivalent dose; CIRT, carbon‐ion radiotherapy; DFI, disease‐free interval; GTV, gross tumor volume; GyE, gray equivalent; IMRT, intensity‐modulated radiotherapy; NOS, not otherwise specified; RT, radiotherapy.
One patient previously was treated with a combination of IMRT and CIRT. This patient underwent IMRT of 56 Gy and 50.4 Gy, respectively, to a high‐risk area and low‐risk area in 28 fractions, followed by a CIRT boost of 15 GyE in 5 fractions to the GTV.
Of the 206 patients, 82 patients were diagnosed with disease recurrence on imaging study only. For those patients, the histology of the primary disease was used.
No patient was found to have distant metastasis.