Nasopharyngeal carcinoma is the type of cancer that originates in the head and neck region. Its location of occurrence is behind the nose in the throat and near to the skull base. Nasopharynx acts as a passageway for the passage of air into the lungs through the throat from the nose. The nasopharynx is the topmost part of the pharynx or the throat. It looks visually like a box-like chamber. Nasopharyngeal carcinoma is a rare kind of cancer. Its incidence rate is almost about 1 or fewer cases reported for every 1,00,000 people. It is linked with the Epstein-Barr virus as the cause of cancer. Other factors like diet, family history, and environmental factors altogether also play an important role in the causation of the disease. (1)
Classification/Types Of Nasopharyngeal Carcinoma
Nasopharyngeal cancer arises from the epithelial cells that are lining the nasopharynx. According to the type of cells that cancer might contain, nasopharyngeal carcinoma is divided into three types:
- Non-keratinizing undifferentiated carcinoma (WHO type 3)
- Non-keratinizing differentiated carcinoma (WHO type 2)
- Keratinizing squamous cell carcinoma (WHO type 1)
Non-Keratinizing Undifferentiated Type: This is the most common type of nasopharyngeal carcinoma and its percentage is almost 60% amongst the cases diagnosed with nasopharyngeal carcinoma. The highest incidence of this type is seen in Hong Kong. It has a gender predisposition; men being more often affected than women. The age range at which it is seen to be most common is the age between 40-60 years. The commonest site for this type to originate is the nasopharyngeal recess. This type is said to be strongly linked to the Epstein-Barr virus.
Non-Keratinizing Differentiated Type: It is less commonly seen than the undifferentiated type of nasopharyngeal carcinoma. Its incidence rate is approximately 12% amongst all the cases detected with nasopharyngeal cancer. This is the least common type of nasopharyngeal cancer. It has a gender predisposition; men being more commonly affected than women. The most common site for this type of carcinoma originates in the lateral wall of the nasopharynx. This type is also said to be associated with the Epstein-Barr virus.
Keratinizing Squamous Cell Carcinoma: There is a presence of keratinization of cells in this type when seen microscopically. Amongst all the cases detected with nasopharyngeal carcinoma, this type accounts for around 25% of those cases. The men are more commonly affected than women. This type of cancer appears at the lateral wall of the nasopharynx. The incidence of metastasis to cervical lymph nodes is quite common. This subtype of nasopharyngeal cancer is said to be weakly linked to the Epstein-Barr virus. Patients who get this type of nasopharyngeal cancer have a very less five-year survival rate. The cause of death in such patients is usually due to metastasis to lymph nodes and as a result of some other local disease. (2)
Usually, surgery is not preferred in nasopharyngeal carcinoma because the location of the tumor is odd and not easily accessible. The surgery is mainly done to excise the lymph nodes that have been involved in the disease and when these lymph nodes cannot respond to other treatment modalities.
In order to excise the tumor mass, endoscopy is done. In this procedure, fiberoptic scopes that are flexible are used. This procedure is not done everywhere; it is done only at selected places.
Usually, the doctors try to control cancer growth with the help of chemotherapy and radiotherapy, but when none of these treatment options work then the lymph nodes in the neck are dissected out. This process is called neck dissection. There different types of neck dissection surgeries.
Partial Type Neck Dissection: In this only those lymph nodes are excised that are present close to the tumor mass and are susceptible to getting involved.
Modified Radical Type Of Neck Dissection: The lymph nodes that are located between the collarbone (clavicle) and the jawbone (mandible) are excised out. Along with the lymph nodes, few nerve tissues and few muscles are also excised. The most important nerve that supplies the shoulder muscles is not harmed.
Radical Type Of Neck Dissection: In this type, all the lymph nodes that are present on one side of the neck are excised out. Along with the nodes, veins, nerves and few muscles are also excised out.
There is three types of nasopharyngeal carcinomas and they are non-keratinizing undifferentiated type; non-keratinizing differentiated type and keratinizing squamous cell carcinoma. Amongst these three, the keratinizing squamous cell carcinoma is said to be weakly linked to the Epstein-Barr virus as the cause. Rest two are said to be linked to the Epstein-Barr virus.
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