Nasopharyngeal Carcinoma and Head and Neck Cancer: A Hong Kong-Specific Context
Nasopharyngeal carcinoma (NPC) has an exceptionally high incidence in Hong Kong — one of the highest globally, with rates of approximately 20–30 per 100,000 population in men, roughly 20–30 times higher than in Western countries. This reflects a convergence of genetic susceptibility in Cantonese populations, Epstein-Barr virus infection and dietary factors associated with traditional preserved foods.
Beyond NPC, other head and neck malignancies — laryngeal, hypopharyngeal, oral cavity and thyroid cancers — share a common treatment-related complication: long-term swallowing dysfunction arising from the effects of radiotherapy on the structures of deglutition.
Radiotherapy is Both the Definitive Treatment and the Primary Source of Injury
Because of the anatomical depth of NPC, surgery is technically challenging and radiotherapy (typically combined with chemotherapy) is the definitive curative treatment. However, the radiation field for NPC and other head and neck cancers frequently encompasses the posterior pharyngeal wall, tongue base, larynx, salivary glands and cervical musculature — all structures critical to swallowing. Both acute and late radiation toxicity can profoundly and permanently impair swallowing function.
Important notice: This guide provides general caregiver information and does not replace individualised assessment by a speech-language pathologist and oncology team. Head and neck cancer patients should receive a baseline swallowing assessment before treatment begins, with regular follow-up during and after treatment.
Specific Swallowing Complications of Radiotherapy
Trismus
Trismus is the progressive restriction of mouth opening caused by radiation-induced fibrosis and contracture of the masticatory muscles and temporomandibular joint.
Effects on eating:
- Severely limited mouth opening makes it difficult to fit food into the oral cavity
- Large food items (whole fruits, large pieces of meat) become impossible to eat
- A toothbrush cannot reach the back teeth, compromising oral hygiene
Management:
- Jaw-stretching exercises (facilitated by devices such as the TheraBite) under the guidance of an SLP or physiotherapist
- Choose flat, thin foods that can be bitten with the front teeth, or transition to soft and puréed diets
- Begin jaw-opening exercises as early as possible — during radiotherapy, not only after it ends
Pharyngeal Fibrosis
Radiation-induced fibrosis of the soft tissues of the posterior pharyngeal wall and upper oesophagus progressively reduces tissue elasticity, weakens the pharyngeal constrictor muscles and narrows the food passage.
Presenting symptoms:
- A sensation of food “sticking” in the throat when swallowing solids
- Frequent need to wash food down with fluid
- Substantially prolonged mealtimes
- Persistent residue sensation after swallowing
Pharyngeal fibrosis is a “late toxicity” — it can develop or worsen months to years after the completion of radiotherapy. Even patients whose swallowing recovered well in the acute phase may experience progressive deterioration years later, making ongoing monitoring essential.
Xerostomia (Dry Mouth)
Head and neck radiotherapy almost inevitably damages the salivary glands, particularly the parotid glands, leading to a dramatic reduction in saliva production. Saliva is critical for swallowing: it lubricates food, helps form the food bolus and contributes to triggering the swallowing reflex.
Effects on eating:
- Dry foods (bread, biscuits, loose fried rice) become almost impossible to eat
- Large quantities of gravy, sauce or soup are needed with virtually every food
- Each swallow requires substantially greater effort
- Chronic xerostomia significantly increases the risk of dental caries and oral infections
Management:
- Carry a water bottle at all times; take frequent small sips to keep the mouth moist
- Use artificial saliva sprays (available from hospital pharmacies)
- Choose high-water-content foods
- Avoid alcohol and caffeine, which exacerbate dry mouth
Acute Toxicity Phase: Dietary Management During and Immediately After Treatment
The period during radiotherapy (typically 6–7 weeks) and the 2–4 weeks immediately after treatment completion represents the peak of acute toxicity.
Typical Acute Phase Symptoms
- Oral mucositis: Widespread ulceration of the oral and pharyngeal mucosa; eating is extremely painful
- Dysgeusia (taste changes): Food may taste metallic, bitter or have no taste; severely impacts appetite
- Odynophagia (painful swallowing): Severe pain with every swallow
- Thick, sticky secretions: Increased viscous oral secretions that are difficult to clear
Acute Phase Dietary Recommendations
| Situation | Recommendation |
|---|---|
| Severe mucositis | Cold or room-temperature liquids and purées (cold food provides mild pain relief) |
| Odynophagia | Take prescribed analgesics and time meals to coincide with peak medication effect |
| Taste changes | Experiment with different temperatures and flavours; prioritise foods the patient can tolerate |
| Thick secretions | Increase fluid intake; some patients find dairy products worsen thick secretions and prefer to avoid them |
If oral intake cannot maintain adequate energy and protein, temporary nasogastric tube feeding may be required to ensure nutritional support throughout the treatment course.
Late Toxicity and Swallowing Rehabilitation
After treatment completion, swallowing rehabilitation is a long-term process requiring sustained SLP follow-up and the patient’s active commitment.
Swallowing Rehabilitation Exercises
The following exercises are individually prescribed by the speech-language pathologist to strengthen pharyngeal muscles and improve coordination:
- Shaker exercise (isometric and isotonic head lifts): Strengthens the suprahyoid muscles and improves laryngeal elevation
- Masako manoeuvre (tongue-hold swallow): Strengthens posterior pharyngeal wall constriction
- Mendelsohn manoeuvre: Trains prolonged laryngeal elevation to improve upper oesophageal sphincter opening
- EMST (expiratory muscle strength training): Strengthens expiratory muscles to improve throat clearing and airway protection
All exercises should be commenced only after SLP assessment, and should be maintained consistently. Rehabilitation exercises are most effective when started early after treatment — ideally before severe fibrosis develops.
VFSS Monitoring Schedule
Regular videofluoroscopic swallowing studies (VFSS) or fibreoptic endoscopic evaluation (FEES) are recommended to objectively track swallowing function:
- 3–6 months post-treatment: First VFSS assessment to confirm current safe IDDSI levels
- 12 months post-treatment: Routine review, or sooner if symptoms change
- 2–3 years post-treatment: Late fibrosis may manifest in this window; continued monitoring is important
- Any symptom deterioration: Immediate reassessment, without waiting for a scheduled appointment
Hong Kong Oncology Speech-Language Therapy Services
HA Multidisciplinary Oncology Care
Cancer centres at major HA hospitals — including Queen Elizabeth Hospital (QEH) in Kowloon Central, Prince of Wales Hospital (PWH) in the New Territories East cluster, and Tuen Mun Hospital (TMH) in the New Territories West cluster — typically provide multidisciplinary oncology care including SLP input for swallowing assessment and rehabilitation before, during and after treatment. Patients should ask their oncologist for SLP referral at the time of diagnosis, not only after swallowing problems become apparent.
Hong Kong Cancer Fund
The Hong Kong Cancer Fund provides a range of support services for cancer patients, including:
- Cancer nurse counselling services
- Patient support groups
- Patient education and nutritional guidance
- Website: cancer.org.hk
- Cancer information hotline: 3656 0800
High-Calorie, High-Protein Soft Diet: Practical Food Options
The nutritional goals for head and neck cancer patients in rehabilitation are typically 2,000–2,500 kcal/day and 1.2–1.5 g protein per kg body weight, within the constraints of the patient’s current IDDSI texture level.
| Food | Characteristics | IDDSI Level |
|---|---|---|
| Steamed egg custard (fortified with full-cream milk) | High protein, high energy, smooth texture | L4–5 |
| Avocado and yoghurt blended | High energy, healthy fat, cold and smooth | L4 |
| Mashed potato (with butter and full-cream milk) | High energy density, adjustable consistency | L4–5 |
| Silken tofu purée (with sesame oil and stock) | High protein, smooth, Cantonese flavour profile | L4–5 |
| Full-cream yoghurt with honey | High protein, no preparation, cold and smooth | L4 |
| Fortified pumpkin soup (thickened to prescribed level) | High vitamins, high energy, adjustable consistency | L4 (thickened) |
Frequently Asked Questions
Q: Is xerostomia after NPC radiotherapy permanent?
A: Some degree of saliva recovery can occur in the months to one year after treatment, but if the salivary glands received a high radiation dose, xerostomia may be a long-term or permanent condition. Modern radiotherapy techniques such as intensity-modulated radiation therapy (IMRT) are designed to spare the parotid glands, but complete sparing is not always achievable given the anatomy of NPC. Artificial saliva and rigorous oral hygiene can substantially improve quality of life.
Q: When can a head and neck cancer patient return to a normal diet?
A: The timeline varies considerably depending on the individual patient, cancer type and treatment regimen. Some patients are able to gradually resume a near-normal diet within 3–6 months of completing treatment, while those with significant fibrosis or trismus may require long-term modified texture diets. Regular VFSS assessment by the SLP provides objective data to guide diet level progression.
Q: Can trismus (restricted mouth opening) be treated?
A: The primary approach to trismus is early and sustained jaw-stretching exercises, ideally using a purpose-designed device such as TheraBite. With consistent effort, functional improvement is possible in many patients. Surgical intervention is occasionally considered for severe cases. The most important principle is to begin prophylactic jaw exercises during or immediately after radiotherapy — not only after severe contracture has developed.
Q: When should post-NPC treatment VFSS reassessment be arranged?
A: The first VFSS evaluation is recommended 3–6 months after treatment completion to establish the current safe IDDSI level and guide rehabilitation. Thereafter, at minimum annual review is appropriate. Immediate reassessment should be arranged whenever swallowing noticeably worsens, if swallowing becomes painful, if unexplained weight loss occurs, if recurrent fever suggests aspiration pneumonia, or if the patient subjectively feels their swallowing has changed from its previous pattern.
Content reviewed regularly to reflect current clinical guidelines. Enquiries: [email protected].