Nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC), also known as nasopharynx cancer, is the most common type of cancer originating in the nasopharynx. The nasopharynx is located at the upper part of the throat, behind the nasal cavity and above the soft palate. NPC most frequently arises in the fossa of Rosenmüller, accounting for over 50% of cases. Unlike other head and neck cancers, NPC exhibits unique epidemiology, pathogenesis, and treatment patterns. It is especially prevalent in certain regions of East Asia and Africa, with a multifactorial etiology involving Epstein-Barr virus (EBV), genetic predisposition, and environmental factors.

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  Diagram showing stage T2 nasopharyngeal cancer.

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  Micrograph showing nasopharyngeal carcinoma positive for Epstein-Barr virus.

Anatomy of the nasopharynx

The nasopharynx is a key anatomical region where air from the nasal passages enters the pharynx. It contains important structures such as:

• The eustachian tube openings, which connect the middle ear to the pharynx.
• Adenoids, part of the immune system.
• Pharyngeal recess, the most common site of NPC development.

The proximity of the nasopharynx to critical structures, including the skull base, cranial nerves, and lymph nodes, contributes to the complexity of NPC diagnosis and treatment.

Signs and symptoms

NPC often presents with non-specific symptoms that can delay diagnosis. Common signs and symptoms include:

Lymph node involvement

• Swelling or lumps in the neck due to metastatic spread to regional lymph nodes. These nodes are typically painless and firm.

Local symptoms

• Nasal obstruction or epistaxis (nosebleeds).
• Persistent nasal discharge.
• Otitis media or hearing loss, often unilateral, due to eustachian tube blockage.
• Headache, facial pain, or trismus (difficulty opening the mouth).

Advanced symptoms

• Cranial nerve palsies: Weakness or paralysis caused by tumor invasion.
• Diplopia (double vision) or blurred vision.
• Numbness in the face due to nerve involvement.

Causes and risk factors

NPC is a multifactorial disease, with contributing factors including viral infections, environmental exposures, and genetic predisposition.

Epstein-Barr virus (EBV)

EBV is a major cause of NPC, especially in types II and III (non-keratinizing and undifferentiated subtypes). EBV DNA is detectable in the majority of NPC tumors. High levels of anti-EBV antibodies are often found in patients and can serve as a diagnostic marker.

Diet

• Salted fish: High consumption of Cantonese-style salted fish and preserved foods containing nitrosamines is strongly associated with NPC in endemic regions.

Smoking and alcohol

• Tobacco use increases the risk of type I (keratinizing) NPC.
• Heavy alcohol consumption may also contribute to risk.

Genetic factors

• Family history of NPC suggests a hereditary component.
• Certain HLA alleles have been linked to increased susceptibility.

Diagnosis

NPC diagnosis involves a combination of clinical evaluation, imaging studies, and histological confirmation.

Clinical evaluation

A detailed history and physical examination are essential. Common findings include:

• Neck masses or lymphadenopathy.
• Nasal or auditory symptoms.

Imaging studies

• MRI: Preferred for assessing local tumor invasion.
• CT scan: Useful for staging.
• PET-CT: Detects distant metastases and guides treatment planning.

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  PET-CT scan showing FDG uptake in nasopharyngeal cancer.

Biopsy

Definitive diagnosis requires biopsy of the primary tumor or involved lymph nodes. Histopathology often reveals undifferentiated carcinoma cells.

Classification and staging

WHO classification

NPC is classified by the World Health Organization into three subtypes:

• 1. Keratinizing squamous cell carcinoma (Type I): Least common and associated with smoking.
• 2. Non-keratinizing carcinoma (Type II)
• 3. Undifferentiated carcinoma (Type III): Most common in endemic regions.

Staging

Staging follows the TNM staging system:

• Stage I: Tumor confined to the nasopharynx.
• Stage II: Extension into nearby tissues or lymph nodes.
• Stage III: Larger tumors or bilateral lymph node involvement.
• Stage IV: Distant metastases or extensive local invasion.

Treatment

Treatment varies based on stage and includes radiation therapy, chemotherapy, or a combination.

Radiation therapy

• External beam radiation: Primary treatment for NPC. Intensity-modulated radiation therapy (IMRT) minimizes damage to surrounding tissues.
• Brachytherapy: May be used for localized disease.

Chemotherapy

• Often combined with radiation in advanced stages.
• Common agents include cisplatin and 5-fluorouracil.

Surgery

• Rarely used due to anatomical constraints but may be considered for residual or recurrent disease.

Prognosis

The prognosis depends on stage at diagnosis and response to treatment:

• Early-stage disease: 5-year survival rates exceed 80%.
• Advanced-stage disease: Lower survival rates due to metastases.

Epidemiology

NPC is rare in most populations (<1 case per 100,000 people) but highly prevalent in:

• Southern China: Endemic areas like Guangdong have rates 25 times higher than the global average.
• North Africa and Southeast Asia: Significant burden in these regions.

Prevention

Preventative measures include:

• Reducing consumption of salted or preserved foods.
• Early detection programs in high-risk populations.
• Vaccination and EBV-related therapies under investigation.

See also

• Head and neck cancer
• Epstein-Barr virus
• Radiation therapy

External links

Classification	ICD-10: C11 MeSH: D009303 DiseasesDB: 8814
External resources