What is the function of a salivary gland?
The salivary glands make saliva and release it into the mouth. Saliva has enzymes that help digest food and antibodies that help protect against infections of the mouth and throat. It is important for healthy teeth and gums but, of course, is most important in chewing and lubricating food so that it can be swallowed easily. Saliva also facilitates speech by keeping the tongue and lips moist and enables a large range of movement.
How many salivary glands do we have?
There are three pairs of major salivary glands:
- Parotid glands: These are the largest salivary glands and are found in front of and just below each ear in the neck. Most major salivary gland tumours begin in this gland.
- Sublingual glands: These glands are found under the tongue in the floor of the mouth.
- Submandibular glands: These glands are found below the lower jaw.
There are also thousands of small (minor) or microscopic salivary glands in the lining of the mouth, nose, and throat.
Where is the most common place to develop a salivary gland tumour?
The most common place to develop a salivary gland tumour is in one of the parotid glands.
Most salivary gland tumours are benign (not cancerous) and do not spread to other parts of the body. These benign tumours are very unlikely to cause a facial palsy, although their removal carries a small risk of this.
How common is cancer of the salivary gland?
Salivary gland cancer is rare, with around 550 cases per year in the UK, more commonly developing in patients over 60 years old. Benign (non-cancerous) tumours of the salivary gland are 200 times more common than cancerous tumours. Benign tumours do have a small risk of becoming cancerous if ignored or untreated for a very long time, usually in the region of fifteen to twenty years.
The exact causes of salivary gland cancer are unknown, but we do know that it is not infectious and cannot be transferred to another person. We also know that it is not caused by a faulty gene, so is not an inherited cancer.
What are the symptoms and signs of salivary gland cancer?
Salivary gland cancer may not cause any symptoms. It is sometimes found during a regular dental check-up or physical exam. Symptoms caused by salivary gland cancer also may be caused by other conditions. A doctor should be consulted if any of the following problems occur:
- By far the most common is a lump (usually painless) in front of or behind and beneath the ear, in the cheek, jaw, lip, or inside the mouth.
- Pain developing in a facial lump that had previously been painless.
- A change in growth pattern of a long-standing facial lump. In other words, a lump that has been present for some time and getting slowly bigger, begins to enlarge faster.
- Progressive facial weakness that develops over several days and perhaps weeks.
- Much less commonly, difficulty opening the mouth widely and facial numbness.
- These may be symptoms of something other than cancer, but early consultation with your doctor is essential, if you do notice these symptoms.
What exams and tests are used to detect and diagnose salivary gland cancer?
Your GP will refer you to an ENT or Head and Neck Cancer specialist who may carry out some of the following tests and examinations. These tests will show whether the tumour is cancer or not. The tests will also show what sort of cancer it is and, depending on the type of investigation you have, will also determine if the cancer has spread to any other parts of your body.
- Physical examination and history taking of your symptoms: An examination of the body to check general signs of health. The head, neck, mouth, and throat will be checked for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).
- CT scan: A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an X-ray machine. A dye may be injected into a vein to make the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
- PET scan (positron emission tomography scan): A procedure to find cancer cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Cancer cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
- Ultrasound examination: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. The picture can be printed to be looked at later.
- Endoscopy: A procedure to look at organs and tissues inside the body to check for abnormal areas. For salivary gland cancer, an endoscope is inserted into the mouth to look at the mouth, throat, and larynx. An endoscope is a thin, tube-like instrument with a light and a lens for viewing.
- Fine needle aspiration (FNA) biopsy: The removal of tissue or fluid from the tumour using a fine/thin needle. A specialist doctor called a cytologist views the tissue or fluid under a microscope to look for cancer cells.
Because salivary gland cancer is rare and can be hard to diagnose, patients should ask to have biopsy samples checked by a cytologist who has a special interest or experience in diagnosing salivary gland cancer.
What is the treatment for salivary gland cancer?
Once a diagnosis has been made, the specialist will, in consultation with a Multi-Disciplinary Team (MDT) of other health care professionals, decide on a treatment strategy.
Surgery (removing the cancer in an operation) is a common treatment for salivary gland cancer. A surgeon may remove the cancer and some of the healthy tissue around the cancer. In some cases, a lymphadenectomy (surgery in which lymph nodes are removed) will also be done.
Even if the doctor removes all the cancer that can be seen at the time of the surgery, some patients may be given radiation therapy afterwards to kill any cancer cells that remain.
Radiation therapy is a cancer treatment that uses high-energy X-rays or other types of radiation to kill cancer cells or stop them from growing. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Interstitial radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type and stage of the cancer being treated.
Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing.
What will happen once treatment is finished?
You may need to have follow-up tests. Some of the tests that were done to diagnose the cancer or to find out the stage of the cancer may be repeated. This is to see how well the treatment is working and whether to continue, change or stop treatment. This is sometimes called “re-staging”.
Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your condition has changed or if the cancer has recurred (come back). These tests are sometimes called follow-up tests or check-ups.
Last reviewed: 16-02-2020 || Next review due: 01-08-2020