Table 2.
Risk classification of local recurrence at various anatomic sites and recommended delineation of clinical target volume
| T1-2(N = 33) | T3-4(N = 19) | ||||||
|---|---|---|---|---|---|---|---|
| Anatomic sites | No | Percentage | Risk of recurrence | Anatomic sites | No | Percentage | Risk of recurrence |
| Levator veli palatine muscle | 26 | 78.8% | High | Levator veli palatine muscle | 14 | 73.7% | High |
| Nasopharynx | 25 | 75.8% | Nasopharynx | 14 | 73.7% | ||
| Prevertebral muscle | 24 | 72.7% | Prevertebral muscle | 11 | 57.9% | ||
| Tensor veli palatine muscle | 20 | 60.6% | Tensor veli palatine muscle | 11 | 57.9% | ||
| Retropharyngeal lymph node | 20 | 60.6% | Foramen lacerum | 11 | 57.9% | ||
| Foramen lacerum | 17 | 51.5% | Posterior Nasal cavity | 10 | 52.6% | ||
| Bottom of sphenoid sinus | 17 | 51.5% | Great wing of sphenoid bone | 9 | 47.4% | ||
| Pterygoid process | 14 | 42.4% | Bottom of sphenoid sinus | 9 | 47.4% | ||
| Great wing of sphenoid bone | 11 | 33.3% | Pterygoid process | 8 | 42.1% | ||
| Parapharyngeal space | 11 | 33.3% | Petrous apex | 8 | 42.1% | ||
| Sphenoid sinus | 10 | 30.3% | Clivus | 8 | 42.1% | ||
| Petrous apex | 8 | 24.2% | Median | Retropharyngeal lymph node | 7 | 36.8% | |
| Posterior Nasal cavity | 7 | 21.2% | Pterygopalatine fossa | 7 | 36.8% | ||
| Jugular Foramen | 7 | 21.2% | Parapharyngeal Space | 6 | 31.6% | ||
| Clivus | 6 | 18.2% | Sphenoid sinus | 6 | 31.6% | ||
| Pterygopalatine fossa | 6 | 18.2% | Jugular Foramen | 5 | 26.3% | Median | |
| Medial pterygoid muscle | 6 | 18.2% | Posterior ethmoid sinusa | 4 | 21.1% | ||
| Foramen ovale | 6 | 18.2% | Hypoglossal canala | 4 | 21.1% | ||
| Foramen rotundum | 4 | 12.1% | Low | Lateral pterygoid musclea | 4 | 21.1% | |
| Posterior ethmoid sinus | 3 | 9.1% | Foramen rotunduma | 3 | 15.8% | ||
| Inferior orbital fissure | 3 | 9.1% | Inferior orbital fissurea | 3 | 15.8% | ||
| Anterior ethmoid sinus | 3 | 9.1% | Cavernous sinusa | 3 | 15.8% | ||
| Oropharynx | 2 | 6.1% | Medial pterygoid muscleb | 2 | 10.5% | Low | |
| Anterior Nasal cavity | 2 | 6.1% | Orbit | 2 | 10.5% | ||
| Frontal sinus | 2 | 6.1% | Foramen ovaleb | 1 | 5.3% | ||
| Hypoglossal canal | 1 | 3.0% | Anterior ethmoid sinus | 1 | 5.3% | ||
| Lateral pterygoid muscle | 1 | 3.0% | Oropharynx | 1 | 5.3% | ||
| Cavernous sinus | 1 | 3.0% | Anterior Nasal cavity | 1 | 5.3% | ||
| Orbit | 1 | 3.0% | Maxillary sinus | 1 | 5.3% | ||
| Maxillary sinus | 1 | 3.0% | Cervical vertebrae | 1 | 5.3% | ||
| Cervical vertebrae | 0 | 0.0% | Frontal sinus | 0 | 0.0% | ||
| Infratemporal fossa | 0 | 0.0% | Infratemporal fossa | 0 | 0.0% | ||
| Hypopharynx | 0 | 0.0% | Hypopharynx | 0 | 0.0% | ||
The anatomic sties with median or high risk should be included in the contouring of CTV
aThe possibility of invasion of these structures was higher in cases with T3-4 (≥ 15%) than cases with T1-2 (< 15%). These anatomic structures were recommended to be included in CTV in locally advanced cases (T3-4)
bAlthough the possibility of invasion of these structures was low in T3-4 cases (< 15%), they were recommended to be included due to median risk of involvement in early-stage diseases (T1-2)