Introduction

Head and neck oncology is challenging. It demands a thorough knowledge of head and neck anatomy to guide multi-modality treatment and the treatment itself can lead to significant impairment in important functions such as swallowing, facial expression and speech. Tumours arising within various head and neck subsites can differ in presentation, clinical course and therapeutic options.

Cancers of the head and neck account for around 6% of malignancies worldwide. It is more common among men, with a male-female ratio of 2–3 : 1. Squamous head and neck cancers tend to affect patients between the ages of 40–70 years. The incidence varies geographically – for instance, nasopharyngeal carcinoma is most frequent in the Far East.

Aetiology

The important aetiological factors in squamous cell carcinomas of the head and neck include:

Pathogenesis and pathology

SCC is thought to develop in a stepwise progression from squamous metaplasia to dysplasia, through carcinoma-in-situ to invasive squamous cell carcinoma. These histological changes are accompanied by molecular alterations which disrupt the regulation of cell proliferation, by inactivating tumour suppressor genes and activating oncogenes.

The majority (90%) of malignant tumours of the head and neck are squamous cell carcinomas. The WHO classification of head and neck cancers is outlined in Box 8.1.

Anatomy

Figure 8.1 shows the anatomical sites in the head and neck. Figure 8.2 demonstrates the anatomical levels of neck nodes and the typical regional lymphatic drainage for head and neck subsites, which are important in planning surgery and radiotherapy. In the unoperated neck, the pattern of lymph node drainage is relatively predictable for different tumour subsites. The risk of occult lymph node metastasis varies according to the primary site and the size of the primary tumour. Clinical assessment of this risk of cervical nodal metastasis dictates subsequent decisions on inclusion of lymph node groups within a neck dissection or radiotherapy target volume during the definitive treatment.

Figure 8.1 Anatomy of the head and neck region.

Figure 8.2 Anatomical levels of neck nodes.

Presentation

Most patients with head and neck cancer present with local symptoms due to the growth and depend on the site of tumour (see later).

Evaluation of patients with head and neck cancer

Important features in the history for head and neck cancer patients are:

Investigations and staging

The objectives of the clinical assessment of a patient with a suspected head and neck cancer are:

Imaging

• Suspicious cervical nodes may be further characterized by ultrasound examination of the neck.

• CT and/or MRI of the head and neck region are used to assess the extent of the primary tumour and the regional lymph nodes (Figure 8.3). MRI is superior for assessing soft tissue infiltration, cartilage invasion and perineural spread. CT is useful for assessing bone involvement and has the advantage of being better tolerated by patients with swallowing difficulties because of its faster speed of acquisition. USS of the neck also has a role in neck staging.

• CT chest (or chest X-ray) may be needed to rule out pulmonary metastases in locally advanced disease. Chest X-ray, however, may not detect small volume metastatic disease.

• ¹⁸FDG PET-CT has a role in assessing suspected tumour recurrence and in detecting occult primary tumours.

Figure 8.3 MRI of nasopharyngeal cancer.

Management of head and neck cancers

Radiotherapy in head and neck cancer (Box 8.4)

Conventional fractionation involves delivering a total dose of 66–70 Gy in 2 Gy daily fraction, 5 days a week. Elective irradiation of the clinically node-negative neck requires a dose of 44–50 Gy in 22–25 fractions.

Box 8.4
Radical radiotherapy in head and neck cancer

Radical radiotherapy

• Position – All patients supine with the head in the neutral position, except nasopharyngeal cancer and parotid tumours and tumours of the ear (neck extended). Mouth bite for oral cavity, nasal cavity and sinus tumours will facilitate normal tissue sparing.

• Immobilization – customized shell

• Localization – CT planning

• Target volume definition:

• GTV – all radiologically visible tumour

• CTV – with 1–2 cm margin depending on the anatomic area. CTV may need editing in the areas of anatomical barriers to spread

• CTV – Figure 8.2 shows anatomical boundaries of nodes and Box 8.2 shows nodes need to be treated for N0 disease. For node positive disease, patients generally receive radiotherapy to bilateral level I–V nodes; the exceptions beings well lateralised T2N1 tongue tumours and T1–2N1 tonsil tumours when just the ipsilateral level I–V nodes may be treated

• PTV – depends on the method of immobilization and ranges from 3–5 mm

• Radiation dose:

• Phase I (see Figure 8.4)

– Photons – 44 Gy in 2 Gy per fraction with a lateral parallel opposed beam to the primary tumour and upper neck nodes

– Photons – 44 Gy in 2 Gy per fraction to anterior neck split with cord and lung shielding

• Phase II

– Photons – 22–26 Gy in Gy per fraction with lateral opposed beam moved anterior to spinal cord

– Photons – 0–6 Gy in 3 fractions to anterior neck split

– Electrons – if posterior neck nodes, need treatment. A total dose of 44–50 Gy to elective nodes and 66–70 Gy to involved nodes is delivered

• Bolus is indicated if:

– there is skin involvement

– close superficial margin

– primary electron treatments e.g. pinna

– postoperative tracheostome site

• Monitoring

• Follow-up to assess and treat toxicity

• Haemoglobin should be maintained above 12 g/dl

• Tolerance dose of organs at risk in Gy (at 2 Gy per fraction)

• Lens 8–10 Gy, cornea 40 Gy, retina 50 Gy, optic nerve 50 Gy, optic chiasm 50 Gy, spinal cord and brain stem 44–48 Gy, hypothalamus 44 Gy

Postoperative radiotherapy

• CTV – surgical bed and areas at risk+1–2 cm

• PTV – dependent on set up error

• Dose – 60–64 Gy in 30–32 fractions to areas at risk 44–50 Gy in 25 fractions to elective nodes

Figure 8.4 Illustration of phases of radiotherapy in locally advanced laryngeal cancer: Phase I treatment volume (green rectagle) includes posterior triangle nodes and during phase II, spinal cord is shielded (red shade). Note shielding of oral mucosa (yellow shade) to minimise mucositis.

The indications for postoperative radiotherapy are based on risk factors (Table 8.1). The treatment target is generally the tumour bed and involved neck to a dose of 60–66 Gy in 30–33 fractions (Box 8.4). Consideration may be given to prophylactic nodal irradiation to a lower dose depending on risk.

Table 8.1 Risk factors for predicting locoregional recurrence in the postoperative setting

	Primary site	Neck nodes
Major risk factors	Positive resection margins	Extracapsular spread
Minor risk factors	Close resection margins (<5 mm)	2 or more involved nodes
	Invasion of soft tissues	More than one lymph node level involved
	Multifocal primary	Involved node >3 cm in diameter
	Perineural invasion
	Vascular invasion
	Poorly differentiated
	T3 or T4 disease

High risk of recurrence is associated with the presence of one major risk factor or two minor risk factors.

Intermediate risk of recurrence is associated with the presence of one minor risk factor.

Factors of less importance in predicting risk of recurrence include: oral cavity primary site; presence of carcinoma-in-situ or dysplasia at the resection margin; and uncertain surgical or pathological findings.

Alternate fractionation schedule studied in head and neck cancer include hyperfractionation (80.5 Gy in 70 fractions over 7 weeks using two 1.15 Gy fractions per day), accelerated fractionation (68 Gy in 34 fractions giving six fractions per week). The CHART trial failed to improve local control in locally advanced head and neck cancer. Though generally hyperfractionation and acceleration improve local control by a modest amount compared with conventional fractionation, these are not universally adopted in clinical practice because of practicality of delivery and the advent of chemoradiotherapy.

Role of primary chemoradiation (Box 8.5)

A meta-analysis showed that concurrent cisplatin with conventional radiotherapy fractionation results in an absolute 5-year survival improvement of approximately 10% compared with radiotherapy alone. This potential survival benefit needs to be carefully weighed against its increased acute toxicity of adding concurrent chemotherapy to radiotherapy for each individual patient.

Box 8.5
Systemic treatment in head and neck cancer

Cisplatin with concurrent radiotherapy

• Cisplatin 100 mg/m² IV 3-weekly on days 1, 22 and 43 (if GFR is >50 ml/min). This is the regimen employed in the EORTC and RTOG trial of postoperative chemoradiotherapy.

• Cisplatin 40 mg/m² (max 70 mg) IV weekly for 6 courses (if GFR is <55 and >40 substitute with carboplatin AUC 5 and no platinum if GFR <40). This regimen is also used in some UK centres.

Cetuximab (when concurrent cisplatin is contraindicated).

The initial dose is 400 mg/m² IV followed by weekly doses are 250 mg/m² for 2–8 weeks.

Neoadjuvant chemotherapy

• Docetaxel 75 mg/m² IV day 1

• Cisplatin 100 mg/m² day 2

• 5-Fluorouracil 1000 mg/m²/day days 1–4

Cycle duration 3 weeks.

Maximum 3 courses, assessment after 2 courses.

Role of postoperative chemoradiation

Two randomized studies (one North American and another European) showed differing benefit and hence its role is not clear.

New treatment approaches

Intensity modulated radiotherapy (IMRT) (Figure 8.5) – the role of IMRT in head and neck cancer is evolving, whereby radiation dose can be reduced to critical structures e.g. spinal cord and side effects can be modified, e.g. minimizing salivary gland toxicity with additional scope for increasing the dose to gross disease.

Figure 8.5 An axial CT slice of the neck shows an IMRT plan with (A) concave isodose patterns around the spinal cord, sparing it from the high-dose region and (B) another plan shows sparing of parotid.

Role of brachytherapy

Brachytherapy using low-dose rate iridium implantation or high-dose rate after loading may be used in a few head and neck subsites at specialist centres. Brachytherapy may be considered for some early tumours of the lip, base of tongue, floor of mouth and anterior tongue, as well as certain small volume tumour recurrences within a previously irradiated site.

Care during and after treatment

Radiotherapy toxicity is discussed on p. 348. Rehabilitation of the patient after completion of treatment involves input from a multidisciplinary team including clinical nurse specialists, speech and language therapists, dietitians, physiotherapists, occupational therapists, dental surgeons, dental hygienists and prosthetic specialists.

Treatment of recurrent disease

The common pattern of recurrence is locoregional. The options for managing recurrent disease depend on the initial treatment. Patients who were treated initially with surgery, may be considered for salvage surgery, radiotherapy or palliative chemotherapy or best supportive care. Patients who developed recurrent disease following previous radical radiotherapy or chemoradiation would be considered for salvage surgery.

The management options for advanced, recurrent or metastatic head and neck cancer depend on factors such as co-morbid conditions, previous treatment, performance status, patient preferences and the nature of their symptoms. Advanced head and neck cancer can have a devastating impact on personal appearance and vital functions such as speech and swallowing. Quality of life is of paramount importance when deciding management in recurrent disease.

Prognosis

The overall 5-year survival for head and neck cancer is around 50%. Prognosis is adversely affected by cervical node involvement. The number of involved lymph nodes, the extent of involved nodal levels and the presence of extracapsular spread all impact overall survival.

Follow-up

Ninety percent of recurrences occur in the first 2 years. A second primary tumour is the leading cause of death of patients successfully treated for early cancers of the head and neck, e.g. lung cancer or other head and neck cancers. Patients are followed up for 5 years to detect recurrent disease and second primary tumours, and in order to manage late morbidity following treatment.

Management of specific cancers