What Is Salivary Gland Cancer? What Causes Salivary Gland Cancer?
Salivary gland cancer is an uncommon type of cancer that starts in the tissue of one of the salivary glands. A salivary gland produces saliva, which keeps the mouth moist and helps the body with digestion.
There are a number of salivary glands inside the mouth and two main types, major and minor. There are three pairs of major salivary glands, these are:
- The parotid glands - the largest and most common salivary glands to suffer tumors, the parotid glands are just in front of each ear.
- The sublingual glands - the smallest of the major salivary glands, these are located at the rear of the jaw.
- The submadibular glands - these salivary glands are at the rear of the jaw.
- Inside the Cheeks
- Voice box (larynx)
The salivary gland is any of the saliva-secreting exocrine glands of the oral cavity.
The World Health Organization places salivary gland tumor types into five main categories:
- Malignant epithelial tumors - e.g. mucoepidermoid carcinoma
- Benign epithelial tumors - e.g. Warthin tumor
- Soft tissue tumors
- Secondary tumors
- Hematolymphoid tumors - e.g. Hodgkin lymphoma
What are the Signs and Symptoms of Salivary Gland Cancer?A symptom is something the patient feels or reports, while a sign is something that other people, including the doctor detects. A headache may be an example of a symptom, while a rash may be an example of a sign.
The signs and symptoms for salivary gland cancer are:
- Difficulty in opening mouth all the way
- Facial muscles feel weak on one side of the face
- Noticeable difference in shape of one side of the neck or face
- Part of the face feels numb
- Salivary gland is in constant pain
- Swelling/lump around jaw, mouth or neck area
What are the Causes of Salivary Gland Cancer?There is still little knowledge of salivary gland cancer but what has been found through research is that some salivary gland cancers have genetic irregularities. In the body there are some genes that control cell reproduction (oncogenes) and some that control their destruction (tumor suppressor genes).
In the case of cancer, one or both of these cell controlling gene types have mutated stopping the correct production and destruction of cells. Exposure to certain cancer causing chemicals (carcinogens) or radiation can cause genetic mutation, however the causes of most salivary gland cancer cases are unknown.
How is Salivary Gland Cancer Diagnosed?Diagnosis of salivary gland cancer normally occurs when one of the above symptoms is noticed, causing the patient to visit their doctor. In order to properly diagnose the cancer the doctor will need to know the patient's medical history and perform a physical exam. This will involve examination of the sides of the face, the mouth and the area around the jaw.
The doctor will mainly be looking for any lymph nodes that seem enlarged as this could be a sign of cancer. They may also be looking for muscle weakness or numbness in part of the face to determine if the cancer has spread to the nerves.
If more detail as to the cancer's spread is needed, the patient may require further tests such as Imaging Tests. These imaging tests can be very effective at determining the location and spread of any cancerous areas, they can also help see if a method of treatment is effectively reducing the cancerous area. The types of imaging tests that can be used are:
- CT or CAT scan (Computed Tomography)
- PET Scan (Positron Emission Tomography)
- MRI (Magnetic Resonance Imaging)
- FNA biopsy (Fine Needle Aspiration) - As suggested by the name, this is when the doctor inserts a fine, hollow needle (attached to a syringe) into the tumor and removes some fluid and cells. This procedure is carried out under local anesthetic. The sample is then analyzed by a cancer diagnosis specialist to determine if it is cancerous.
- Incisional biopsy - In this type of biopsy, a surgeon will anesthetize the area, make a small incision and take away a small part of the tumor. This procedure is occasionally used if a FNA biopsy has not been able to extract enough of the tumor for suitable analysis.
- Surgery - There are some cases where FNA biopsies have turned out inconclusive, but the presence of cancer has been clear from other methods of diagnosis (sometimes the physical exam or imaging tests are enough to determine the cancer without needing an FNA biopsy at all). In this instance, surgery may be advised to remove the tumor entirely. The removed mass can then be tested to see if it was malignant.
What are the Treatment Options for Salivary Gland Cancer?
SurgeryThis is normally the primary form of treatment for salivary gland cancer. The degree of surgery entirely depends on the size and location of the tumor. If the tumor is large, the whole salivary gland may need to be removed along with any nerves and ducts that the cancer may have spread to. If the cancerous area is small and easy to get to, then the surgeon may only need to remove the tumor and a small amount of surrounding tissue.
Here is some more detail of the types of surgery used to treat salivary gland cancer, and when they may be used:
- Parotid gland surgery - this gland is the most common place to find salivary gland tumors. It is difficult to perform surgery on this gland because the facial nerve passes right through it. The surgeon would enter by making a small incision on the side of the face just in front of the ear. If the cancer has spread, the entire gland would need removing (total parotidectomy) and possibly even the facial nerve and surrounding tissue.
However it is quite often in this type of salivary gland cancer that the tumors occur in the superficial lobe, located near the outside of the gland. As long as the cancer hasn't spread, removing this lobe can solve the problem (superficial parotidectomy), and means the surgeon can avoid damaging the facial nerve.
- Submandibular gland surgery - also known as sublingual gland surgery, this surgery is performed if the tumor is in the sublingual glands or the submandibular glands. In this case the entire gland would need to be removed, and possibly some of the neighboring bone and/or tissue. There is also a chance that some nerves that control the tongue may need to be removed.
- Minor salivary gland surgery - Minor forms of salivary gland cancer can appear in parts of the mouth such as the tongue, lips and throat. During surgery, the cancer is removed along with some surrounding tissue.
- Reconstructive surgery - As some of the above surgeries involve dissection of the facial muscles, bones and/or parts of the throat, the patient may need reconstructive surgery. A plastic surgeon would need to replace or repair parts of the face to aid in breathing or chewing. This may involve skin/tissue grafts and even nerve grafts depending on the location and scale of the original surgery.
Radiation TherapyThis is when high-powered energy particles or beams (such as x-rays) are directed at the affected part of the body to slow the growth of or destroy cancer cells.
Radiation therapy can be useful when the tumor is in a hard to reach area which would prevent surgery. However this method can be used to kill any malignant (cancerous) cells that could be left over after surgery. It might also be used to reduce the size of a tumor before surgery.
It is possible that the location of the tumor is in an area that makes it too risky for surgery. In this instance radiation therapy is used on its' own.
External beam radiation therapy is the most common form of radiation therapy used to treat salivary gland cancer. This therapy is very similar to an x-ray but with a more intense level of radiation. The treatments are usually given once a day, five days a week for up to seven weeks.
It has been discovered in recent years that there are newer types of radiation therapy that could be more successful than the typical method. An example of this is accelerated hyperfractionated radiation therapy, in which radiation is given twice daily over a shorter period of time.
The use of 3D imaging technology can now also be implemented into the therapy. Using MRI or CT scans the doctor can figure out the best angle and direction for the radiation to enter the body, maximizing effectiveness and minimizing risk. Examples of these methods are:
- 3D-CRT (Three-dimensional conformal radiation therapy)
- IMRT (intensity-modulated radiation therapy)
ChemotherapyChemotherapy (Chemo) is a method of treatment where anti-cancer drugs are ingested either through the mouth or intravenously to kill the cancerous cells. Each drug can be used on their own, however combinations of two or more is the most common practice. Some of the drugs used are:
- 5-fluorouracil (5-FU)
- Doxorubicin (Adriamycin®)
- Paclitaxel (Taxol®)
- Vinorelbine (Navelbine®)
Chemotherapy is not a common method of treatment for salivary gland cancer but its' use is being explored. It has been used to aid radiation therapy or surgery as it can weaken the cancer cells and reduce the size of tumors. Chemo is not advised for patients in poor health.
What are the Risk Factors of Salivary Gland CancerA risk factor is something which increases the likelihood of developing a condition or disease. For example, obesity significantly raises the risk of developing diabetes type 2. Therefore, obesity is a risk factor for diabetes type 2.
Salivary gland cancer risk can be increased by the following factors:
- Exposure to radiation - Patients who have received radiation therapy for cancers in the head and neck have a higher risk of developing salivary gland cancer. Experts say that exposure to a certain number of X-rays may also slightly increase the risk..
- Age - The older you get, the higher your risk is of developing salivary gland cancer. Even though the majority of patients with this type of cancer are older, it can develop at any age.
- Family History - Although rare, it is known that some people have greater genetic risk of developing salivary gland cancer than others.
- Exposure at the workplace - There are certain substances, suggested by studies - such as nickel alloy dust and silica dust - that might increase risk of salivary gland cancer. However, due to limited data these links are not yet proven.
- Cell phone use
- Tobacco and Alcohol consumption
Risk Factors of SurgeryAs previously mentioned, some salivary gland cancer surgery may involve incision or dissection of the mouth, skin, bone and or facial nerves. If this is the case the patient may experience the following:
- Anesthesia problems
- Healing trouble
- Excessive bleeding
- Wound infections
- Pain after surgery - can be treated with medication.
- Nerve damage - one side of the face droops or the patient can have trouble swallowing and/or talking.
- Gustatory sweating - also known as Frey Syndrome, this is when nerves grow back unusually which can lead to sweating over some areas of the face when chewing. This can be treated either with more surgery or medication.
Risk Factors of RadiationThere are a few possible side effects when using radiation therapy. External beam radiation alone can cause the following (note: these symptoms usually disappear after the treatment):
- Skin can appear sunburned
- Feeling Nauseous
- Dry mouth due to decreased saliva production
- Throat and mouth sores
- Dry, sore throat
- Difficulty in swallowing
- Total or partial loss of taste
- Bone pain and damage
- Existing teeth problems worsen
- Damage to thyroid gland
Risk Factors of ChemotherapyChemotherapy is quite an aggressive form of treatment, as it attacks cells that are dividing rapidly. The problem is that as well as attacking cancer cells, it affects some healthy quick dividing cells such as hair follicles and cells in the lining of the mouth. The degree and nature of the side effects is dependent on which drugs are used and how long the treatments have been going on. The following are some of the common side effects of chemotherapy and are usually short term and some can be treated:
- Reduced appetite
- Low white and red blood cell count (greatens risk of infections and can lead to fatigue)
- Low blood platelet count (easily bruised)
- Hair loss
- Sores in mouth
How can Salivary Gland Cancer be Prevented?As there is little knowledge of the exact cause, there is no guaranteed way of preventing salivary gland cancer. The best that can be done to prevent it is to be wary of the risk factors. Eating a healthy diet, exercising regularly and avoiding tobacco and alcohol are effective ways of minimizing risk.
Also if you do work around nickel alloy dust, silica dust or radioactive substances, be sure to protect yourself against them. And remember that if you do suffer any of the symptoms listed in this article, it is worth seeing your doctor as the earlier it is caught the better.