Nasopharyngeal Cancer

Definition/diagnostic criteria

Nasopharyngeal cancer (NPC) is a malignant tumour arising from the epithelial cells of the nasopharynx, located behind the nose and above the back of the throat. It is distinct from other head and neck cancers due to its unique epidemiology, aetiology, and clinical behaviour.

Epidemiology

NPC is relatively rare in the UK, with an incidence of approximately 1 per 100,000 people annually. It is more prevalent in Southeast Asia, North Africa, and the Arctic region. In the UK, it predominantly affects males more than females, typically presenting between the ages of 50 and 60. Risk factors include genetic predisposition, Epstein-Barr virus (EBV) infection, and exposure to certain environmental factors such as consumption of salt-cured foods and smoking.

Diagnosis

Clinical features: The symptoms of NPC can be non-specific and often mimic other less serious conditions, leading to delayed diagnosis. Common clinical features include:

• Painless neck lumps (due to lymph node metastasis)
• Nasal obstruction or congestion
• Epistaxis (nosebleeds)
• Hearing loss or ear fullness (often unilateral and due to eustachian tube obstruction)
• Headaches
• Cranial nerve palsies in advanced cases

Investigations and typical abnormalities: Diagnosis of NPC involves a combination of clinical examination and imaging, followed by histopathological confirmation.

• Nasopharyngoscopy: Direct visualisation of the nasopharynx using a flexible nasoendoscope to identify any suspicious lesions.
• Imaging: MRI of the nasopharynx and skull base is preferred for assessing the extent of the primary tumour and involvement of adjacent structures. CT scans are useful for evaluating bony involvement. PET-CT scans may be employed for staging and detecting distant metastases.
• Biopsy: Histological examination of biopsy samples from the nasopharynx confirms the diagnosis.

Treatment

The primary treatment modalities for NPC are radiotherapy and chemotherapy, with the approach depending on the stage of the disease.

• Early-Stage NPC (I and II): Radiotherapy alone is often curative for early-stage NPC. Intensity-modulated radiotherapy (IMRT) is the standard, as it allows precise targeting of the tumour while sparing adjacent normal tissues.
• Locally advanced NPC (III and IV): Concurrent chemoradiotherapy (CRT) is the standard of care for locally advanced disease. Cisplatin-based chemotherapy is commonly used. Adjuvant chemotherapy may be considered in certain cases.
• Recurrent or metastatic NPC: Palliative chemotherapy is used to control symptoms and prolong survival.

Prognosis

The prognosis for NPC varies based on the stage at diagnosis, with earlier stages having better outcomes. The 5-year survival rate for stage I NPC exceeds 90%, but drops significantly for advanced stages. Factors influencing prognosis include tumour size, extent of local invasion and presence of metastases. Advances in radiotherapy techniques and the integration of chemotherapy have improved survival rates over recent decades. Regular follow-up is essential for detecting recurrence and managing late effects of treatment.