Anatomy
Risk Factors
Signs and Symptoms
Diagnostic Tests
Prognosis
Follow-up

Anatomy

The nasopharynx has a cuboidal shape. The lateral walls are formed by the eustachian tube and the fossa of Rosenmuller. The roof, sloping downward from anterior to posterior, is bordered by the pharyngeal hypophysis, pharyngeal tonsil, and pharyngeal bursa with the base of the skull above. Anteriorly, the nasopharynx abuts the posterior choanae and nasal cavity, and the posterior boundary is formed by the muscles of the posterior pharyngeal wall. Inferiorly, the nasopharynx ends at an imaginary horizontal line formed by the upper surface of the soft palate and the posterior pharyngeal wall.

Unlike other squamous cell cancers of the head and neck, nasopharyngeal cancer does not appear to be linked to excess use of tobacco and alcohol. Factors thought to predispose to this tumor include:

• Chinese (or Asian) ancestry.[1]
• Epstein-Barr virus (EBV) exposure.
• Unknown factors that result in very rare familial clusters.[2]

Symptoms and signs at presentation include:

• Painless, enlarged lymph nodes in the neck (present in approximately 75% of patients and often bilateral and posterior).
• Nasal obstruction.
• Epistaxis.
• Diminished hearing.
• Tinnitus.
• Recurrent otitis media.
• Cranial nerve dysfunction (usually II–VI or IX–XII).
• Sore throat.
• Headache.

In the patient who presents with only cervical adenopathy, the finding of EBV genomic material in the tissue after amplification of DNA with the polymerase chain reaction lends strong evidence for a nasopharyngeal primary tumor, and a concerted search should be conducted in that area.[3]

Diagnosis is made by biopsy of the nasopharyngeal mass. Workup includes: [4]

• Careful visual examination (by mirror or endoscopic examination).
• Documentation of the size and location of the tumor and neck nodes.
• Evaluation of cranial nerve function and hearing.
• Skull films (especially base-of-skull views) evaluating neural foramina.
• Complete computed tomographic (CT) scan or magnetic resonance imaging (MRI) with views delineating the upper and lower extent of the lesion.
• Chest x-ray.
• Hemogram.
• Chemistry panel.

Any clinical or laboratory suggestion of distant metastasis may prompt further evaluation of other sites. Careful dental and oral hygiene evaluation and therapy is particularly important prior to initiation of radiation treatment. MRI is often more helpful than CT scans in detecting abnormalities and in defining their extent.[4-6]

Major prognostic factors adversely influencing outcome of treatment include:[7]

• Large tumor size.
• A higher tumor (T) stage.
• The presence of involved neck nodes.

Other factors linked to diminished survival that were present in some, but not all, studies include:

• Age.
• Nonlymphoepithelial histology.
• Long interval between biopsy and initiation of radiation therapy.
• Diminished immune function at diagnosis.
• Incomplete excision of involved neck nodes.
• Pregnancy during treatment.
• Locoregional relapse.
• Certain EBV antibody titer patterns.

Small cancers of the nasopharynx are highly curable by radiation therapy, and patients with these small cancers have shown survival rates of 80% to 90%.[8]

Moderately advanced lesions without clinical evidence of spread to cervical lymph nodes are often curable, and patients with these lesions have shown survival rates of 50% to 70%.

Patients with advanced lesions, especially those associated with clinically positive cervical lymph nodes, cranial nerve involvement, and bone destruction have disease that is poorly controlled locally by radiation therapy with or without surgery, and the lesions often develop distant metastases despite local control.[9,10]

Follow-up for patients includes:

• Routine periodic examination of the original tumor site and neck.
• Chest x-ray.
• MRI or CT scan.
• Blood work.

Positron emission tomography scans may be useful in planning treatment for patients with suspected recurrence.[11] Monitoring of patients should include:

• Surveillance of thyroid and pituitary function.
• Dental and oral hygiene.
• Jaw exercises to avoid trismus.
• Evaluation of cranial nerve function, especially as it relates to vision and hearing.
• Evaluation of systemic complaints to identify distant metastasis.

Although most recurrences occur within 5 years of diagnosis, relapse can be seen at longer intervals. The incidence of second primary malignancies is less than after treatment of tumors at other head and neck sites.[12]

Poorly differentiated squamous cell cancer has been associated with EBV antibodies.[3,13] High-titer antibodies to virus capsid antigen and early antigen, especially of high IgA class, or high titers that persist after therapy, have been associated with a poorer prognosis.[14] This finding remains under evaluation.

Tumors of many histologies can occur in the nasopharynx, but this discussion, like the American Joint Committee on Cancer nasopharynx staging, refers exclusively to squamous cell types of tumors.

References

1. Chien YC, Chen JY, Liu MY, et al.: Serologic markers of Epstein-Barr virus infection and nasopharyngeal carcinoma in Taiwanese men. N Engl J Med 345 (26): 1877-82, 2001.  [PUBMED Abstract]
   
   
2. Decker J, Goldstein JC: Risk factors in head and neck cancer. N Engl J Med 306 (19): 1151-5, 1982.  [PUBMED Abstract]
   
   
3. Feinmesser R, Miyazaki I, Cheung R, et al.: Diagnosis of nasopharyngeal carcinoma by DNA amplification of tissue obtained by fine-needle aspiration. N Engl J Med 326 (1): 17-21, 1992.  [PUBMED Abstract]
   
   
4. Cummings CW, Fredrickson JM, Harker LA, et al.: Otolaryngology - Head and Neck Surgery. Saint Louis, Mo: Mosby-Year Book, Inc., 1998. 
   
   
5. Mendenhall WM, Riggs CE Jr, Cassisi NJ: Treatment of head and neck cancers. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds.: Cancer: Principles and Practice of Oncology. 7th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2005, pp 662-732. 
   
   
6. Laramore GE, ed.: Radiation Therapy of Head and Neck Cancer. Berlin: Springer-Verlag, 1989. 
   
   
7. Sanguineti G, Geara FB, Garden AS, et al.: Carcinoma of the nasopharynx treated by radiotherapy alone: determinants of local and regional control. Int J Radiat Oncol Biol Phys 37 (5): 985-96, 1997.  [PUBMED Abstract]
   
   
8. Bailet JW, Mark RJ, Abemayor E, et al.: Nasopharyngeal carcinoma: treatment results with primary radiation therapy. Laryngoscope 102 (9): 965-72, 1992.  [PUBMED Abstract]
   
   
9. Fandi A, Altun M, Azli N, et al.: Nasopharyngeal cancer: epidemiology, staging, and treatment. Semin Oncol 21 (3): 382-97, 1994.  [PUBMED Abstract]
   
   
10. Teo PM, Chan AT, Lee WY, et al.: Enhancement of local control in locally advanced node-positive nasopharyngeal carcinoma by adjunctive chemotherapy. Int J Radiat Oncol Biol Phys 43 (2): 261-71, 1999.  [PUBMED Abstract]
    
    
11. Zheng XK, Chen LH, Wang QS, et al.: Influence of [18F] fluorodeoxyglucose positron emission tomography on salvage treatment decision making for locally persistent nasopharyngeal carcinoma. Int J Radiat Oncol Biol Phys 65 (4): 1020-5, 2006.  [PUBMED Abstract]
    
    
12. Cooper JS, Scott C, Marcial V, et al.: The relationship of nasopharyngeal carcinomas and second independent malignancies based on the Radiation Therapy Oncology Group experience. Cancer 67 (6): 1673-7, 1991.  [PUBMED Abstract]
    
    
13. Neel HB 3rd, Pearson GR, Taylor WF: Antibodies to Epstein-Barr virus in patients with nasopharyngeal carcinoma and in comparison groups. Ann Otol Rhinol Laryngol 93 (5 Pt 1): 477-82, 1984 Sep-Oct.  [PUBMED Abstract]
    
    
14. Lin JC, Chen KY, Wang WY, et al.: Detection of Epstein-Barr virus DNA the peripheral-blood cells of patients with nasopharyngeal carcinoma: relationship to distant metastasis and survival. J Clin Oncol 19 (10): 2607-15, 2001.  [PUBMED Abstract]
    
    

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