Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC), also known as nasopharyngeal cancer or nasopharynx cancer, is the most common cancer originating in the nasopharynx. It predominantly affects the postero-lateral nasopharynx or pharyngeal recess (fossa of Rosenmüller).

NPC is notably more prevalent in certain regions of East Asia and Africa, and it is most common in males. This type of cancer is characterised by undifferentiated squamous cell carcinoma, involving squamous epithelial cells.

Signs and Symptoms

NPC often presents as a lump or mass on both sides towards the back of the neck due to metastatic spread to the lymph nodes, causing them to swell. These lumps are usually not tender or painful.

Additional symptoms include headaches, sore throat, trouble hearing, breathing, or speaking, facial pain or numbness, blurred or double vision, trouble opening the mouth, and recurring ear infections without an upper respiratory tract infection. Larger tumours can cause nasal obstruction, bleeding, and a "nasal twang." Metastatic spread may lead to bone pain or organ dysfunction.

Causes

NPC is caused by a combination of viral, environmental, and genetic factors. The Epstein-Barr virus (EBV) is significantly associated with NPC, particularly in WHO types II and III tumours. Genetic susceptibility and the consumption of preserved meats and salted fish containing carcinogenic volatile nitrosamines are other likely causes. Chronic sinusitis is also being investigated as a potential cause.

Diagnosis

Classification

The World Health Organisation (WHO) classifies nasopharyngeal carcinoma into three subtypes:

• Type 1: Squamous cell carcinoma, typically found in older adults.
• Type 2: Non-keratinizing carcinoma.
• Type 3: Undifferentiated carcinoma, commonly found in younger children and adolescents.

Staging

Staging is based on clinical and radiologic examination. Most patients present with Stage III or IV disease.

• Stage I: Small tumour confined to nasopharynx.
• Stage II: Tumour extending locally or with limited neck (nodal) disease.
• Stage III: Large tumour with or without neck disease, or tumour with bilateral neck disease.
• Stage IV: Large tumour involving intracranial or infratemporal regions, extensive neck disease, and/or distant metastasis.

Risk Factors

Nasopharyngeal carcinoma is not linked to excessive use of tobacco, but certain risk factors increase susceptibility:

• Having Chinese or Asian ancestry.
• Exposure to Epstein-Barr virus (EBV).
• Unknown factors resulting in rare familial clusters.
• Heavy alcohol consumption.

Treatment

Radiation Therapy

Radiation therapy uses high-energy x-rays to target and kill cancer cells. External radiation therapy involves a machine that directs radiation to the cancer site, often using a mesh mask to keep the patient still. Advanced techniques like intensity-modulated radiation therapy (IMRT) and stereotactic radiation therapy minimise damage to healthy cells.

Chemotherapy

Chemotherapy uses drugs to stop cancer cell growth by killing the cells or preventing their division. It can be administered systemically or regionally. Systemic chemotherapy circulates through the bloodstream to reach cancer cells throughout the body, while regional chemotherapy targets specific areas. Adjuvant chemotherapy can be used after radiation to reduce the risk of recurrence.

Immunotherapy

The FDA has approved toripalimab-tpzi (LOQTORZ) for the first-line treatment of metastatic or recurrent, locally advanced NPC, and as a single agent for recurrent unresectable or metastatic NPC with disease progression after platinum-containing chemotherapy.

Surgery

Surgery may be performed to determine the presence of cancer or to remove it from the body. It is typically considered when the tumour does not respond to radiation therapy. If cancer has spread to lymph nodes, these may also need to be removed.

Epidemiology

As of 2010, NPC resulted in 65,000 deaths globally, up from 45,000 in 1990. It is uncommon in the United States and most other nations but highly prevalent in southern China, particularly in Guangdong, where it accounts for 18% of all cancers. It is sometimes referred to as "Cantonese cancer" due to its high incidence in this region.

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Self-assessment MCQs (single best answer)

What is the most common cancer originating in the nasopharynx?

Nasopharyngeal carcinoma is notably more prevalent in which regions?

Which virus is significantly associated with nasopharyngeal carcinoma (NPC)?

What is the World Health Organisation (WHO) Type 3 classification of nasopharyngeal carcinoma?

Which staging of nasopharyngeal carcinoma involves large tumours affecting intracranial regions or distant metastasis?

Which symptom is NOT typically associated with nasopharyngeal carcinoma?

What type of therapy uses high-energy x-rays to target and kill cancer cells in nasopharyngeal carcinoma?

Which FDA-approved drug is used for the first-line treatment of metastatic or recurrent, locally advanced NPC?

Which dietary factor is associated with an increased risk of nasopharyngeal carcinoma?

What stage is characterised by a small tumour confined to the nasopharynx?