Definition
The term “Head and Neck Cancers” refers to a heterogeneous group of malignant tumours that have arisen from anatomical sites that include upper aero-digestive tract and neck. The most common head and neck cancer seen in Singapore is the undifferentiated nasopharyngeal carcinoma (NPC). This is the 6th most common cancer in Singaporean males and nearly 300 new cases are diagnosed every year.

The larynx is the next most common site of disease followed by tumours in the oral cavity and oropharynx. Histologically, 95% of these tumours are squamous cell carcinomas (HNSCC). The other 5% consists of a variety of different tumours, each with its distinct clinical behaviour and presentation requiring different management approaches.

The other head and neck cancers are categorised as follows: oral cavity, oropharynx, hypopharynx, salivary glands, nose and paranasal sinuses. Thyroid cancers are yet another important cancer in this anatomical region, constituting about 5% of all head and neck cancers.

Etiology
Two main etiological agents are tobacco smoking and alcohol. A variety of hereditary, environmental, occupational and hygienic factors also contribute to the disease. Epstein Barr Virus infection is one of the known etiological agents for nasopharyngeal cancer in endemic areas like Singapore, Southern China and the Mediterranean basins.

Head and neck cancers are more prevalent in male than female (3:1) and the patients are generally of poorer nutritional status and overall state of health. More than 40% of the patients have regional lymph nodes involvement at the time of diagnosis and 10% of the patients have distant metastasis. Moreover, due to the effects of alcohol and tobacco smoking, approximately 5% of head and neck cancer patients present with a second primary cancer in the upper aero-digestive tract at the time of diagnosis.

Eventually, 20% of the patients will develop a second cancer. This is especially true for patients who continue to smoke and consume alcohol. This phenomenon is due to a “field cancerisation effect” as the entire respiratory mucosa is at risk of neoplastic changes. They may also develop lung cancer.

Signs and symptoms
Although head and neck cancers are a heterogeneous group of malignant tumours they have some common signs and symptoms that should alert physicians to look out for them.

One of the most common presentations of head and neck cancers is the neck lump. This is especially so for cancers of the nasopharynx, tonsils, tongue base, supraglottis and pyriform sinus where the incidence of nodal metastases is high. Cancers of the submandibular or parotid gland can also present as neck swellings. It is imperative that patients with neck lumps go for a complete ENT examination before any attempt is made to excise them.

Beware of non-healing ulcers in the oral cavity and oropharynx, as they can be malignant. The most common oral ulcers, also known as apthous ulcers, are superficial and often painful. These ulcers should heal or show signs of healing within 1 - 2 weeks. Ulcers that fail to heal or are obviously invasive and should be biopsied without delay.

Patients with persistent hoarseness should have a laryngoscopy to exclude laryngeal cancers. This is especially so for smokers and those with significant alcohol consumption. The most common cause of hoarseness is laryngitis, but the hoarseness rarely persists for more than 2 weeks if given appropriate medical care.

Blood stained nasal discharge or phlegm is a presenting symptom in a significant number of patients with NPC. It is a more ominous symptom than frank epistaxis that is commonly caused by bleeding from Little’s area. However, tumours such as nasopharyngeal angiofibromas, haemangiomas as well as NPC can present as recurrent epistaxis and should not be ignored.

Ear symptoms such as tinnitus or a blocked ear can sometimes occur because of Eustachian tube obstruction from NPC. This is especially so if the symptoms are unilateral. Anyone with effusion in the middle ear, but with no obvious cause such as an upper respiratory tract infection should have an ENT evaluation and nasal endoscopy.

Oropharyngeal and hypopharyngeal tumours usually present with odynophagia and dysphagia.

Maxillary tumours can present to the dentist with toothache or facial swelling. If the pterygoid muscles are invaded with cancer, patients can present with trismus. Visual impairment and other cranial nerve palsies are often signs of locally advanced nasopharyngeal cancer.

Sometimes, if early symptoms are ignored, patients may be brought to medical attention due to systemic signs of weight loss, anaemia and lethargy due to metastatic disease.

Diagnosis and staging
Most early premalignant changes or in situ carcinomas of the oral mucosa occur as red (erythroplasia) or white (leukoplakia) patches that should be immediately apparent on visual examination. In areas less easily visualised directly, such as the larynx and hypopharynx, early lesions cause symptoms such as chronic hoarseness, chronic sore throat, referred otalgia, or dysphagia. These symptoms demand examination of the involved structures by direct or indirect laryngoscopy.

In patients presenting with a suspicious neck mass, a complete head and neck examination usually reveals primary malignant tumour. If it does not, a thorough search for occult primary cancers both above and below the clavicles is warranted. Technologic advances in fiberoptics and in flexible and rigid endoscopes now provide excellent upper airway visualisation that previously required special skills in indirect mirror examination. Endoscopic evaluation should include the nasopharynx, oropharynx, hypopharynx, larynx, and oesophagus. Pathologic biopsy could be obtained from primary site or the lymph nodes.

Three-dimensional imaging with computed tomography (CT) and magnetic resonance imaging (MRI) is often used to supplement clinical evaluation and staging of primary tumours and regional lymph nodes. A chest radiograph should be done to exclude any lung metastases or second primary in lung.

The American Joint Committee on Cancer (AJCC) has developed staging criteria for cancers arising in the head and neck region. The criteria undergo regular re-evaluation and modification. The stage groupings used for head and neck cancers are based on T (primary tumour), N (regional node), and M (distant metastasis) designations. Because of variations in the growth, behaviour, and prognosis of head and neck cancers according to site of origin and extent, differences exist in the staging criteria for each anatomic site and region in the head and neck.

Staging criteria for the primary lesion are site specific. However, except for tumours arising in the nasopharynx, there is uniformity in the nodal staging criteria and stage grouping. Hence, for NPC the modified UICC staging is used commonly.

6th AJCC clinical tumour stage and groupings for Head and Neck cancer

Clinical tumour staging characteristics for regional lymph nodes and distant metastases