Cancers of the Nasopharynx
Table of Contents
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General
- Highest incidence in China and Eskimos.
- Peak years in the 4th and 5th decades.
- Etiology includes viral (EBV), genetic (HLA A2 and HLA BSIN2), and environment (dust and diet due salted fish).
- 2.4 male:: 1 female
Pathology
WHO classification | Prevalence | Former Terminology | Risk Factors | Radiosensitivity and control |
Type 1. keratinizing Squamous cell carcinoma | 20% US | Squamous cell | Associated with EtOH and Tob but not EBV | Same as other H&N cancers |
Type 2. Nonkeratinizing Squamous cell carcinoma +/- lymphoid stroma | 30-40% US | Transitional cell, Intermediate cell, Lymphoepithelial (Regaud) | Positive for anti-EBV | See note |
Type 3. Undifferentiated carcinoma +/- lymphoid stroma | 40-50% US; 99% in endemic areas (eg. SE China) | Anaplastic Clear cell Lymphoepithelial (Schminke) |
Positive for anti-EBV | see note |
Note: Lymphoepithelioma may be radiosensitive and have better LRC but same OS due to distant failures; Lymphoepithelial more often small, submucosal, and sometimes difficult to detect; indeed, they may be clinically occult.
- Rare tumors are lymphoma, adenocarcinoma, plasmacytoma, melanoma, and sarcoma.
Juvenile Nasopharyngeal Fibroma (Non-malignant)
- also called angiofiromas
- benign, strongly vascularized tumors in H&N region
- intracranial spread occurs in 25% of cases
- JNF require several months after RT to remit
- sometimes complete remission does not occur after years, although there is no further growth.
Anatomy
- Cuboid area from the base of skull behind the nasal cavity.
- begins anteriorly at the posterior choana
- soft palate
- lateral walls (vault)
Clinical Presentation
- epitaxis, decreased hearing, and nasal obstruction.
Routes of Spread
- Inferior: orophaynx
- Anterior: nasal cavity
- Posterior: clivus
Superior
- superiorly the spinoid sinus (CN VI and V2 are most commonly involved).
- Petrosphenoidal Syndrome: all the of the cavernous sinuses are involved. CN III, IV, VI ,V1, & V2.
Lateral
- The lateral walls, which is the most common site for NPX CA, contain the Eustachian tube and the fossa of Rosenmuller.
- The upper lateral walls only have 2 layers the pharyngeal aponeurosis and the mucous membrane.
Parapharyngeal space
- contains the lateral retropharyngeal nodes,
- internal jugular vein, internal carotid artery,
- CN IX, X, XI, XII
- and the cervical sympathetic chain.
Nodal Risk
- 90% ipsilateral with 50% bilateral at presentation and typically the retropharyngeal nodes are affected. Subclinical disease is about 70%.
- elective irradiation of the level II-V nodes and retrophrengeal nodes bilaterally, regardless of the status of the neck.
Distant metastasis
- 3% to bones, lung, and liver.
Definitive Surgery
* small tumors that are restricted to postrior nasal cavity and the nasopharynx
* 100% local control
Definitive Radiation
- Radiotherapy is the mainstay of treatment and chemotherapy is added as an adjuvant in advanced cases.
Early Stage (T1, T2a and N0) | RT alone |
---|---|
Advanced Stage (T3, T4 or N1+) Intergroup (Al-Sarraf JCO 1998) |
Chemoradiation followed by adjuvant Cisplatin and 5-FU for 3 cycles. |
Altered fraction/Post-operative RT | No role |
Radiation Dose
- ≥ 70 Gy to tumor and gross LN
- Lymphoepithelioma may be give 500 cGy less.
- ≥ 50 Gy to nodal regions.
Radiation Field
- Areas to Cover: CTV56-59.4 (RTOG 0615)
- entire nasopharynx
- anterior 1/2 to 2/3 of the clivus (entire clivus, if involved),
- skull base (foramen ovale and rotundum bilaterally must be included for all cases),
- pterygoid fossae,
- parapharyngeal space,
- inferior sphenoid sinus (in T3-T4 disease, the entires phenoid sinus)
- and posterior fourth to third of the nasal cavity and maxillary sinuses (to ensure pterygopalatine fossae coverage).
- The cavernous sinus should be included in highrisk patients (T3, T4, bulky disease involving the roof of the nasopharynx).
- Lymph nodes groups to cover
- bilateral submandibular Ib if LN+.
- bilateral II-V
- retropharyngeal LN
Complications
- xerostomia, otitis media, trismus, neck fibrosis, STS, CN dysfunction, myelitis, retinopathy, and optic nerve - increases with increasing fraction size).
Results
T stage | LC | OS-5 |
---|---|---|
T1 | 95% | 75% |
T2 | 80% | 65% |
T3 | 70% | 55% |
T4 | 70% | 30% |
- Patients who do better Lymphoepithelioma (LC about 90-100%) and undifferentiated carcinoma, younger, females.
OS with RT is about 60%. For early lesions, the LC is about 80%
Reirradiation
Brachytherapy
- Superfical persitence or recurrence (MGH)
- 40 Gy EBRT in 20 fractions
- 20 Gy in 2 applications to mucosal surface
EBRT
- Deep persistence or recurrence
- EBRT > 60 Gy (0% OS-5 < 60 Gy vs 45% for > 60 Gy)
- total mucosal dose ~ 125 Gy.
- Complications worse for total doses > 100 Gy
SBRT
- SRT effective, lower risk than reported SRS [2]
- 15-20 Gy with < 8 Gy to optic chiasm, brainstem and cavernous sinus
IMRT Re-irradiation DVH criteria[4]
- 10 Gy and 10% for brainstem
- 4 Gy & 5% for spinal cord
- 8 Gy & 5% for optic nere and chiasm
- 10 Gy and 5% for orbit
- 10 Gy & 10% for temporal lobe
Toxicities
- ototoxicity 10%
- crainal neuropathy 10%
- brain necrosis 7%
- soft-tissue necrosis/fibrosis 3%
Studies
Study | Pts, N | LCR, % | 5-Yr OS | Complication, % |
---|---|---|---|---|
Hwang, 98 | 74 | 49 | 37 | 23 |
Yan, 83 | 162 | 14 | 23 | 34 |
Vikram, 86 | 15 | 61 | 55 | 20 |
Wang, 87 | 51 | 45 | 4 | |
Pryzant, 92 | 53 | 35 | 21 | 15 |
Wei, 93 | 34 | 63 | 33 | 20 |
Metastatic (M1) NPC
- Cisplatin based chemotherapy (20% CR rates)
- For patients with CR some institutions give definitive RT alone to H&N as 20% have long term survival.
Bibliography
1. Italian, 1988 (1979-83): PMID 3047335 — "Adjuvant chemotherapy with vincristine, cyclophosphamide, and doxorubicin after radiotherapy in local-regional nasopharyngeal cancer: results of a 4-year multicenter randomized study." Rossi A et al. J Clin Oncol. 1988 Sep;6(9):1401-10.
2. Guangzhou; 2007 (China)(1999-2005) PMID 17601682 — "Outcome of fractionated stereotactic radiotherapy for 90 patients with locally persistent and recurrent nasopharyngeal carcinoma." (Wu SX, Int J Radiat Oncol Biol Phys. 2007 Nov 1;69(3):761-9.)
3. Harvard; 1987 PMID 3597157 — "Re-irradiation of recurrent nasopharyngeal carcinoma—treatment techniques and results." Wang CC et al. Int J Radiat Oncol Biol Phys. 1987 Jul;13(7):953-6.
4. Chua; Reirradiation of nasopharyngeal carcinoma with intensity-modulated radiotherapy. Radiotherapy and Oncology 77 (2005): 290-294.
page revision: 70, last edited: 18 May 2009 22:56