ACR Codes: 2.3
Nasopharyngeal Carcinoma
• Incidence 0.5-2/100,000 in US
• Endemic in southern China where incidence is 15-20/100,000.
• Additional populations with intermediate risk include SE Asia, northern Africa and North American Eskimos.
• More common in males (3:1), bimodal age distribution
• EBV is almost always present in NPC, indicating that this virus plays an oncogenic role. The viral titer can be used to monitor therapy or possibly as a diagnostic tool in the evaluation of patients who present with a metastasis from an unknown primary.
• Exposure to environmental carcinogens, especially high levels of volatile nitrosamines (specifically, those in Cantonese-style salted fish), has been implicated in this complicated disorder; carcinogens related to smoking, formaldehyde exposure, and radiation have also been implicated.
• Diets of salted fish, nitrates, preserved vegetables, Chinese herbs have been implicated in this disease. The cooking of salt-cured foods releases volatile nitrosamines which distribute over the nasopharyngeal mucosa when carried by steam.
• Having a first degree relative with NPC incrses odds of NPC 7.6-fold; this has led to recommended screening of all first degree relatives of pt with NPC.
• NPC classic clinical triad consists of a neck mass, nasal obstruction with epistaxis, and serous otitis media.
• The most common presenting complaints in patients with NPC are headache and a mass in the neck.
• Nasopharyngeal carcinoma produces few symptoms early in its course, with the result that most cases are quite advanced when detected.
• Once the tumor has expanded from its site of origin in the lateral wall of the nasopharynx, it may obstruct the nasal passages and cause nasal discharge or nosebleed.
• Obstruction of the auditory tubes may cause chronic ear infections, and patients may experience referred pain to the ear.
• Metastasis of cancer to the lymph nodes of the neck may also be the first noticeable sign of the disease.
• Characteristic radiology findings include the early triad of nasopharyngeal mucosal asymmetry, ipsilateral
retropharyngeal LAD, mastoid opacification.
• Invades superiorly > inferiorly
• Anatomical sites of tumor invasion (>30% in one study):
Lateral/Posterior: levator/tensor pallatini, pharyngobasilar fascia, parapharyngeal fat space, pre-vertebral muscle
Anterior: nasal cavity
Superior: skull base (pterygoid process, clivus, spenoid body, and petrous), foramens lacerum > ovale > rotundum, sinuses cavernous > sphenoid > ethmoid, orbit
• Compared to other head/neck cancers has tendency for early metastatic spread.
-Lymph node metastases occur in 75 to 90 percent and bilateral neck nodes are present in over 50 percent of patients .
-Distant metastases are detected at initial diagnosis in approximately 5 to 11 percent of patients, and 38 to 87 percent have evidence of distant dissemination at autopsy.
-The most frequent sites of distant metastases are bone (70 to 80 percent of metastases), lung, and liver.
• External beam radiation therapy is the primary mode of management of NPC, both at the primary site and in the neck
• Chemotherapy adjunctive to radiotherapy in advanced NPC has been controversial with conflicting literature reports.
• Nasopharyngectomy is reserved only for treatment of recurrent NPC with limited disease
• Prognosis for NPC is based on multiple factors: primary tumor extension, disease level in the neck, histologic subtype, and patient's sex (increased survival rate for women).
Reference(s): Brant, WE, Helms HA. Fundamentals of Diagnostic Radiology. Lippincott Williams & Wilkins. 2007. 241-270.
King, AD, Lam, WW, Leung ST, et al. MRI of local disease in nasopharyngeal carcinoma: tumor extent versus tumor stage. Br J Radiol 1999; 72:734.
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