Cancers of the head and neck occur when cancerous cells develop and grow in an uncontrolled way forming tumours. Not all tumours in the head and neck are cancerous.⁴

Most head and neck cancers begin in the squamous cells (thin, flat cells that form the surface of the skin, or lining of the throat).⁵

Cancers of the head and neck include the following areas: ^4,5

• Mouth (oral cavity) – including lips, cheeks, hard palate and the first two thirds of the tongue, as well as the gums and tonsils.
• Larynx – is also known as the voice box, and contains the vocal cords used for making sound. The larynx connects the windpipe (tube that connects to the lungs) with the lower part of the throat.
• Pharynx – also known as the throat. Cancer can affect any three areas that make up the pharynx including:
  • Nasopharynx – this is the upper part of the throat, behind the nose
  • Oropharynx – include the base of the tongue to the tonsils in the back of the throat
  • Hypopharynx – is the lower region of the throat, including behind the voice box.
• Nasal cavity and sinuses – the nasal cavity is the area inside the nose. The area behind the nose consists of four sinuses which impact on the sound and tone of speech.
• Salivary glands – is where saliva is produced to help digest food and protect against infections. Most of the tumours found here are typically benign (non-cancerous).

Cancers of the brain, thyroid gland, eye and oesophagus are not included in the classification under ‘head and neck’ cancer.⁵

People who have a first degree relative (such as a sibling or parent) have an increased risk for developing some head and neck cancers.⁴

Some genetic conditions such as Fanconi anaemia and Dyskeratosis congenita (disorders of blood) have an increased risk of developing cancers of the throat and mouth. ⁶

The TNM system is used to classify cancers of the head and neck. Based on this system, specialists can work out the stage (I-IV) of cancer; Stage I and II represent early stage head and neck cancer and Stage III and IV represent advanced stage cancer.⁷

• Tumour (T) – describes the size of the tumour and the extent the cancer has spread.
• Nodes (N) – describes whether the tumour has spread to nearby lymph nodes. Nodes can be graded from N0, where there has been no spread, through to N3, where the cancer has spread to other lymph nodes.
• Metastasis (M) – describes whether the cancer has spread to other areas of the body outside of the lung. Metastasis can be graded from M0, where there has been no spread through to M1c, where the cancer has spread to other organs of the body and produced additional tumours.