In the United States, salivary gland cancer is responsible for less than 1 percent of all cancers. It affects 1 in every 100,000 people. There are estimated to be 2,000-2,500 cases each year in the U.S.
Common treatments include surgery, radiation, and chemotherapy. Avoiding risk factors can help reduce the likelihood of diagnosis; however, a genetic cause may play a role.
- It is a very rare form of cancer, making up less than 1 percent of all cancers in the U.S.
- Diagnosis is typically carried out by imaging tests and incisional biopsy.
- Complications include Frey's syndrome and facial drooping.
What is salivary gland cancer?
The salivary glands are located in the mouth, they may be painful if there is cancer.
The mouth contains many salivary glands, some major and some minor. Salivary gland cancer occurs when one of these glands develops a cancerous tumor. There are 3 pairs of major salivary glands:
The parotid glands, positioned just in front of each ear, are the largest salivary glands; they are the most likely to develop a tumor.
The sublingual glands are found under the tongue; they are the smallest of the major salivary glands. The submandibular glands are below the jaw.
There are 450-750 microscopic minor salivary glands all around the mouth. Locations include:
- the sinuses
- the tongue
- inside the cheeks
- the nose
- the larynx
- voice box
Tumors are less likely to occur in these minor glands, but if one does develop, there is a 50-50 chance that it will be cancerous, or malignant. Salivary gland tumors can be benign or malignant, and they include hematolymphoid tumors, such as Hodgkin lymphoma.
A person who has salivary gland cancer may experience:
- Difficulty in opening mouth completely.
- Weak facial muscles on one side of the face.
- Swelling or a lump around jaw, mouth, or neck area.
- Noticeable difference in the shape of one side of the neck or face.
- Part of the face feels numb.
- The salivary gland is in constant pain.
Any painless lump that is not linked to an infection should be investigated.
Salivary gland cancers have not been extensively researched, and the cause remains a mystery. However, a genetic cause is thought likely. Certain genes, called oncogenes, control cell reproduction; another set of genes control cell destruction, these are known as tumor suppressor genes. In the case of cancer, one or both of these cell-controlling gene types have mutated.
This means that the correct production and destruction of cells no longer takes place. Exposure to certain cancer-causing chemicals, or carcinogens, or radiation, can cause genetic mutation.
Research suggests that a reduction in the use of X-rays for dental and other procedures is linked with a reduction in salivary gland cancer.
The following factors can increase the risk of developing salivary gland cancer:
- Radiation therapy for cancers in the head and neck increase the risk of developing salivary gland cancer later.
- Older patients have a higher risk, although salivary gland cancer can happen at any age.
- Genetic factors can increase the risk.
- Workplace exposure to substances such as nickel alloy dust and silica dust may be a factor.
Other potential risks that are being researched include cellular phone use, diet, and tobacco and alcohol consumption.
Diagnosis is aided by imaging tests, including computed tomography (CT) scans.
The physician will ask the patient about their medical history and examine the sides of the face, the mouth, and the area around the jaw. If any lymph nodes seem to be enlarged, this could be a sign of cancer.
Muscle weakness or numbness in the face could indicate that the cancer has spread to the nerves.
Imaging tests may be carried out to determine the location and spread of any disease. A biopsy may be used to take tissue for analysis. In an incisional biopsy, a small incision is made, and a part of the tumor is taken for examination.
Depending on the initial findings, surgery may be carried out to remove and test the whole tumor.
Treatment for salivary cancer, as for many cancers, often involves surgery, radiation therapy, chemotherapy, or a combination of these.
Surgery is normally the primary form of treatment for salivary gland cancer. The whole salivary gland may need to be removed, along with any nerves and ducts where the cancer may have spread. If it is small and easy to access, it may be necessary only to remove the tumor and a small amount of surrounding tissue.
Radiation therapy directs high-powered energy particles or beams at the tumor to slow, or destroy, the cancer cells. The most common type of radiation therapy for salivary gland cancer is external beam radiation therapy. It provides an intense level of radiation.
Treatments are usually given daily, 5 days a week for up to 7 weeks. Newer types of radiation therapy that may be more successful include accelerated hyperfractionated radiation.
Chemotherapy is used when the cancer has spread to other parts of the body. The patient takes medication either by mouth or intravenously to kill the cancerous cells. A variety of drugs are available that can either be used on their own or in combination with other drugs, such as 5-fluorouracil (5-FU), or carboplatin.
Complications of surgery include:
- reactions to the anesthetic
- slow wound healing
- excessive bleeding
Nerve damage may cause one side of the face to droop, and the patient may have difficulty swallowing or talking. Reconstructive surgery may be possible, and a speech therapist can help with restoring some of the lost functions.
Gustatory sweating, or Frey Syndrome, is when nerves grow back in an unusual way, which can lead to sweating over some areas of the face when chewing. This can be treated with more surgery or medication. Adverse effects of radiation therapy generally include:
- burning of the skin
These typically disappear after treatment. Radiation therapy for salivary gland cancer may also travel to other parts of the head and neck. There might be:
- Dry mouth due to decreased saliva production.
- Throat and mouth sores.
- Dry, sore throat.
- Difficulty swallowing.
- Total or partial loss of taste.
- Bone pain and damage.
- Worsening of dental problems.
- Damage to the thyroid gland.
- Ringing or sensation of fullness in the ears
Chemotherapy kills cancer cells, but it can also affect some healthy cells, such as hair follicles, and cells in the lining of the mouth. Common side effects include:
- Reduced appetite, nausea, and vomiting.
- Low white and red blood cell count, increasing the risk of infections and fatigue.
- Low blood platelet count, so that the body is more easily bruised.
- Hair loss.
- Mouth sores.
After completing treatment, the patient will be monitored closely by a doctor. It is important to attend all follow-up appointments as this can help to minimize any side effects of treatment, and deal with any recurrence early.
Prognosis depends on the stage at which the cancer is diagnosed. Stage 1 salivary gland cancers have a 5-year life expectancy of 91 percent relative to normal for a person's age group. This drops to 39 percent if the cancer is diagnosed at Stage 4 (with more advanced disease).
Prevention is difficult, since the exact cause of salivary gland cancer is unknown. However, a healthy diet, regular exercise, and avoiding tobacco and alcohol can minimize the risk. One article suggests that an increased consumption of fruits and vegetables, particularly those high in vitamin C, and avoiding food high in cholesterol may be beneficial.
People working in environments where there is nickel alloy dust, silica dust, or radioactive substances must use appropriate protection.