Epidemiology
Head and neck cancer is the sixth most common cancer worldwide and accounts for 4% of all cancer in the UK. It is more common in men (65–90% of cases) than women and incidence increases with age, particularly over 50 years. It can be classified into oral cavity (44%), larynx (31%) and pharynx (25%). These patients have particular problems due to the close proximity of the tumours to important structures in the head and there can be severe social consequences to treatment, e.g. the loss of voice in laryngeal cancer.
Aetiology
The most significant risk factors are smoking (sixfold increased risk), chewing tobacco or betel nuts, and alcohol consumption, particularly spirits which act synergistically with tobacco. Other factors include UV light exposure (lip cancer), viral infections (EBV, HPV), environmental exposure (wood dust, nickel) and radiation (thyroid and salivary gland cancer).
Nasopharyngeal cancer is most common in Southeast Asia and is seen in Arabs and Inuits, but worldwide it is rare. There is a strong association with the major histocompatibility complexes H2B, BW46 and B17. Case-controlled studies in Chinese patients have suggested a link between salted fish consumption and the incidence of nasopharyngeal cancer. Mutations in the TP53 tumour suppressor gene are recognised and associated with a worse outcome.
Pathophysiology
The majority of head and neck cancers are squamous cell carcinoma (90%), except in nasopharyngeal tumours, which tend to be anaplastic. Other rare forms include adenoid cystic carcinoma, plasmacytoma, melanoma, sarcoma and lymphoma. Up to 20% of patients can have multiple primary sites at presentation
Clinical examination
Physical examination is the best means for detecting a cancer of the head and neck region. The teeth, gingivae and entire mucosal surface should be inspected. The lymphoid tissue of the tonsillar pillars should be inspected and any asymmetry noted. Tongue mobility should be evaluated. The floor of the mouth, tongue and cheeks should be palpated using a bimanual technique (one gloved finger inside the mouth and the second hand under the mandible). Palpation should be the last step of the examination due to stimulation of the gag reflex. Any suspicious lesions require biopsy.
The neck should be examined, documenting the location of any mass and noting the relationship to major structures, such as the salivary gland, thyroid and carotid sheath. The thyroid should be palpated.
Cancers of the oral cavity
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