Categories: Radiation Oncology

Radiation in Head and Neck Cancer

Head and neck cancer are tumors of the upper aerodigestive tract. In India, around 30% of all cancers are HNCs. Head and Neck cancer comprises oral cancers, oropharynx, larynx, nasopharynx and hypopharynx, paranasal sinuses, salivary glands and ear. In India, 60% of patients present with advanced disease. The average age of onset of Head and neck cancer is 60 years. Cancers of the head and neck are more commonly found in people with higher incidences of smoking, alcoholism and poor oral hygiene. The most important risk factor in the development of head and neck cancers is tobacco and smoking. Smoking or chewing tobacco is associated with 80-85% of head and neck malignancies. There is a synergistic effect of combining alcohol and tobacco for developing cancers to head and neck sites. There is an increase in the incidence of second malignancy of the head and neck and other sites (lung, oesophagus) in heavy and persistent smokers. Dental disease, sharp teeth and trauma from ill-fitted dentures are also risk factors for cancer. Epstein-Barr virus infection is found in nasopharyngeal cancer. Human papillomavirus (HPV) associated is with oropharyngeal and oral tumours.

When diagnosed early, head and neck cancer has good chances for cure, but at present, there is no established screening programme. For the prevention of head and neck cancer tobacco cessation is essential. The majority (85- 90%) of cancers of the head and neck are squamous cell carcinomas (SCC) arising from mucosal cells. Histological diagnosis is necessary to confirm the diagnosis before treatment to ensure the correct management.

The symptoms depend on the primary site and the adjacent structures involved. Non-healing ulcer, hoarseness, difficulty in swallowing, discomfort or pain on eating, referred aural pain, trismus or cranial nerve palsies. More non-specific symptoms of weight loss, anorexia or generalized discomfort can also be seen in the patients.

The most common prognostic marker at the time of diagnosis is the stage. The work-up requires the histological diagnosis and full examination under anaesthetic of the aerodigestive tract for accurate staging. Cross-sectional imaging with computed tomography (CT) or magnetic resonance imaging (MRI) with contrast enhancement is for detailing the anatomical extent of the primary lesion and any nodal involvement. Imaging of the chest with a chest x-ray or CT is required for metastatic workup.

The treatment is usually between radical surgery postoperative radiotherapy (or chemoradiotherapy) or primary radical radiotherapy (or concurrent chemoradiation) with possible neck dissection for residual disease. The decision is usually determined by the site of the primary tumour, the size of the primary tumour, evidence of lymph node involvement and patients co-morbidity or individual preference.

The chief aim of radiotherapy in head and neck cancer is organ preservation. In early laryngeal cancer, equivalent cure rates are with radical radiotherapy and laryngectomy, but radiotherapy has the advantage of normal voice preservation. The purpose of postoperative radiotherapy is to improve locoregional control. It has been estimated that cancer-specific and overall survival at 5 years might be improved by about 10% with postoperative radiotherapy. Postoperative radiotherapy should commence within 6 weeks of surgery. Indications for postoperative radiotherapy are positive (involved) resection margins, extracapsular lymph node spread, close resection margins, perineural invasion, stage III/IV multicentric primary oral cavity tumours with involved nodes.

All head and neck cancer patients should have an assessment by a dietician prior to any treatment. Patients receiving radical radiotherapy will have a course of treatment over many weeks and will develop mucositis and dysphagia in the acute phase. Nasogastric tube or percutaneous gastrostomy should be actively considered in patients, especially those with large treatment fields and are essential for patients being considered for concurrent chemoradiation where the acute toxicity is usually increased. Patients need to have a full dental assessment prior to radiotherapy. Dental extractions should be done a minimum of 1- 2 weeks before starting radiotherapy. Patients need to be encouraged to use fluoride toothpaste or gel.

Once radiotherapy has been decided as the treatment, Patients need to be informed of all possible side effects. The next step is immobilization. It is essential for accurate treatment delivery that patients have good quality reproducible immobilization. These shells are commonly thermoplastic cast and created specifically for the patient during the planning phase. The patient then has a subsequent CT scan in the mask.

The conventional schedule for radiotherapy to head and neck cancer involves the delivery of 66–70 Gy in 2 Gy fractions over 6.5 to 7 weeks treating 5 days per week. Concurrent cisplatin chemotherapy and definitive radiotherapy is the standard treatment for radical therapy. IMRT is the technique to treat tumour tissue while minimizing the exposure of healthy adjacent normal tissue. IGRT has its purpose to correct for motion and set-up errors by imaging the treatment area on a daily basis. IGRT is more valuable than IMRT in view of the high degree of conformality. Patients require a satisfactory full blood count and adequate renal function. Nutritional support is essential and a feeding tube is advised in patients undergoing combination treatment.

In radiotherapy, the side effects (apart from fatigue) relate to structures within the radiation field. They can be divided into acute (early) or late side effects. Mucositis will develop in the treatment field for all patients with head and neck cancer. It may be mild (grade 1/2), and grade 3 and 4, dysphasia secondary to mucositis, loss of taste, loss of appetite and thickened secretions that lead to weight loss in head and neck cancer patients. Skincare should include washing with lukewarm water and unperfumed soap, avoiding shaving until treatment is completed. Once the skin is broken then a barrier product should be used. Patients should be reviewed regularly post-treatment to monitor the resolution of skin and mucosal reactions. Fatigue is seen in many patients receiving radical radiotherapy.

Dry mouth is a common late side effect of radiotherapy to the head and neck. After radiotherapy, these patients are often left with xerostomia. The 5-year survival rate for stage I patients is more than 70- 80%, the 5-year survival rate for stages III and IV patients is less than 40 to 50%.

Dr. Pooja Khullar, Consultant – Oncology, Radiation Oncology, Dharamshila Narayana Superspeciality Hospital, Delhi

Narayana Health

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