Nasopharyngeal Carcinoma

Nasopharyngeal Carcinoma

The nasopharynx is the uppermost part of the pharynx (upper throat) that lies behind the nose. The most common form of cancer in the nasopharynx is nasopharyngeal carcinoma (NPC). In most cases, NPC is poorly differentiated and may emerge at any site in the upper respiratory tract. Cancer in NPC begins in the epithelial cells that line the surface of nasopharynx.

Epidemiology

Although NPC is rare in the United States and UK, its frequency is high in Asia and Northern Africa. The disease develops much more in males than in females. Children can develop NPC.

The sub-types of NPC

The classification of NPC given by the World Health Organization is as follows:

1) Squamous cell carcinoma (keratinizing carcinoma) – this is the most common type in the United States

2) Non-keratinizing carcinoma

3) Undifferentiated carcinoma

Etiology or Risk factors

The risk factors associated with NPC are the following:

Epstein-Barr virus (EBV) infection: EBV infection is associated with NPC.

Ethnic background: Chinese Americans are most prone to this disease in United States. Others who are also affected are Asian-American groups, African Americans, Hispanics/Latinos and whites.

Smoking: Studies have shown that smoking may be a cause for developing NPC.

Genetic factors: Certain inherited tissue types can increase the risk of developing NPC.  The percentage of NPC patients who have one or more family members who suffered from the same disease ranges between 6 and 15.5.  Although, this is one of the highest risks of having NPC, close to 90 percent cases are spontaneous and are unrelated to family history.

Diet: An increased risk of NPC is associated with consumption of salted fish containing carcinogenic volatile nitrosamines.

Symptoms

Symptoms at initial stages:

  • Trismus (inability to normally open the mouth)
  • Blood-stained nasal draining
  • Pain
  • Otitis media (inflammation of the middle ear)
  • Nasal regurgitation
  • Hearing loss and cranial nerve palsies
  • Nasal obstruction
  • Loss of appetite and loss of weight

Symptoms at advanced stages:

  • Masses in the neck (lymph nodes with cancer)
  • Bone pain or organ dysfunction
  • Loss of appetite and loss of weight

 

Diagnosis

Clinical examination of the throat: The doctor examines the swollen lymph nodes in the neck simply by touching the area. A mirror is sometimes used to have a better view inside the throat.

Nasopharyngoscopy: A nasopharyngoscope is light and lens bearing tube-like instrument for viewing the nasal passage. It is inserted inside the nose for having a look inside. It may also be used to obtain tissue samples for microscopic examinations.

Biopsy: Cells and tissues removed from the affected part can be visualized under microscope to examine whether the tumor is malignant or not. Biopsy can be of the two types: FNA (fine needle aspiration of a lymph node) biopsy and endoscopic biopsy via the nasopharynoscope.

Chest X ray: It is done to see whether the cancer has spread to lungs or not.

CT scanning of the nasopharynx and neck: CT scan takes the help of X-rays to generate images that can be seen on a computer screen.

MRI of the nasopharynx and neck: This procedure uses a magnet and radio waves to generate images of the head and neck region. Images can be visualized on a computer screen.

These imaging studies can be used to see if cancer has spread.

Treatment

Radiotherapy

Radiotherapy is the mainstay therapy for NPC. Although treatment with radiotherapy controls the primary tumor, it does not prevent the appearance of distant metastases. Radiation therapy dose and field margins are planned according to the location and size of the primary tumor and lymph nodes. External-beam radiation therapy (EBRT) is used in most cases, but intracavitary or interstitial implants may be used to boost the radiation therapy.

Intensity-modulated radiation therapy (IMRT) may also be used to reduce incidence of xerostomia (dry mouth) and provide a better quality of life than conventional radiation therapy. IMRT showed less acute toxicity (skin, mucous membrane and pharynx) compared with conventional radiotherapy.

Chemotherapy

Chemotherapy in combination with radiotherapy is the best treatment available. It reduces the dose of radiotherapy and hence related side effects. Chemotherapy prior to radiation is used to make the tumor smaller and therefore more susceptible to curative radiation therapy. The common chemotherapeutic agents used are  cisplatin and 5-FU. Chemotherapy after radiotherapy or a combination of radiotherapy and chemotherapy is used to kill the cancer cells left after the main treatment.

In children, the Mertens protocol NPC-91-GPOH (Society of Pediatric Oncology and Hematology) has given the best results. This protocol uses interferon-beta based immunotherapy after the application of chemotherapy and radiotherapy.

Surgery

Surgery is not a usual practice for the treatment of NPC patients. Surgery may be done to get rid of affected lymph nodes in the neck or a tumor from the nasopharynx.

Prognostic factors

The prognosis depends on the following factors:

  • The stage of NPC
  • The kind of NPC
  • The size of tumor
  • Age and health of patients

Several staging methods have been developed. The TNM staging developed by American Joint Committee for Cancer Staging is mostly used.

The five-year survival rate when the tumor has metastasized is 38%, although survival rates are rising with new methods of treatment.

References:

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  4. Wei WI, Sham JS. (1996) Cancer of the Nasopharynx. In: Myers EN, Suen JY eds. Cancer of the Head and Neck. Philadelphia: W.B. Saunders,:277-93.
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  8. This article was originally published on September 3, 2012 and last revision and update was 9/4/2015.