Salivary gland cancer: symptoms and treatment

Saliva keeps the mouth and throat moist, helps us swallow and digest food, protects the teeth and guards against infection. Cancer Research UK says there are three main pairs of major salivary glands and more than 600 minor glands in the lining of the mouth and throat.

The major glands are the parotids, just under the lobes of the ears, the submandibular glands, under each side of the jawbone, and the sublingual glands, under the tongue. Most cancers start in the parotid glands, with the rest in the submandibular, sublingual or minor glands.

Because the glands contain several kinds of cell, many different cancers can arise. The type of cancer is named after the type of cell it started in.

Cancer Research UK states that most salivary gland tumours are not cancer. For the parotid gland, 3 in 4 are benign. NHS Greater Glasgow and Clyde guidance, written for GPs, gives similar figures: 80% of parotid tumours and 50% of submandibular tumours are benign.

The commonest benign type is pleomorphic adenoma, usually slow growing. Cancer Research UK says doctors are likely to suggest surgery to remove these because there is a small risk of cancer developing within the tumour, and radiotherapy may be offered if one is likely to return.

The practical point is that a lump cannot be classed by feel alone. Examination, imaging and a sample of cells are needed.

Cancer Research UK lists the possible symptoms as a painless lump or swelling in the jaw, cheek, mouth or neck, numbness in part of the face, drooping on one side of the face from facial palsy, pain in the area of the lump, problems swallowing, difficulty opening the mouth fully, and swelling on one side of the face.

Many of these can be caused by benign tumours or other conditions, but it is important to have unusual symptoms checked. The GP guidance describes how a lump is separated from generalised swelling of a gland: a discrete lump suggests a tumour, while swelling of the whole gland suggests infection or a blocked duct.

Cancer Research UK says the causes are not known, but several factors raise risk. Age is the main one, and most people who develop it are in their 50s or 60s, although the overall risk remains small because the cancer is rare.

Radiation exposure is another. This may be radiotherapy to the head or neck for another cancer such as Hodgkin lymphoma or thyroid cancer, or contact with radioactive substances at work. There is some evidence of risk from radioiodine treatment for thyroid cancer, and radiotherapy for a childhood cancer may increase risk for at least 20 years afterwards.

Family history may play a part, but the charity says the evidence is unclear and it may reflect shared lifestyle rather than inherited genes. There is no national screening programme for salivary gland cancer in the UK.

Most people start with a GP, who asks about symptoms, examines the area and may arrange tests. Cancer Research UK says a GP might feel around the jaw and neck, arrange blood tests and a chest X-ray, and then refer to a head and neck specialist. The NHS Greater Glasgow and Clyde guidance advises referral to ENT as urgent if a neck lump persists beyond 3 weeks, and to maxillofacial services for a floor of mouth lesion lasting more than 3 weeks.

Specialists usually arrange a neck ultrasound and a fine needle aspiration, which uses a fine needle and syringe to take cells from the lump for examination under a microscope. The charity says ultrasound or CT may guide the needle for deeper lumps, and a local anaesthetic injection can be used.

Further tests may include CT, PET or MRI scans, and testing for gene and protein changes. A biopsy of tissue is not a common test but may be used for minor salivary gland cancers, and panendoscopy under general anaesthetic may be used for areas that are hard to reach.

A pathologist identifies the cell type from the sample, and the doctor then explains which gland is affected and the cell type.

Cancer Research UK says treatment depends on where the cancer is, its size, whether it has spread and your general health. Surgery, radiotherapy and chemotherapy are the main treatments, and targeted drugs or immunotherapy may also be used. You might have one or more of these.

Surgery is the most common treatment, and the operation depends on which gland is involved and how far the cancer has grown. If cancer has spread to lymph nodes, a neck dissection may remove some of them. Possible problems after surgery include changes in eating, talking and appearance, plus infection, blood clots and bleeding.

Chemotherapy may be used for advanced cancer or when surgery or radiotherapy is not possible. After treatment you have regular check-ups, which may include blood tests or scans. Support is available from Cancer Research UK, and a charity, Salivary Gland Cancer UK, supports people with rarer types.