Salivary glands make and release saliva that lubricates your mouth and throat, starts the digestion of your food, and coats the lining of the upper airway to help protect you from infections. Tumors, either benign (not cancer) or malignant (cancer), can arise in any of these glands.
There are three pairs of major salivary glands:
- Parotid glands Located in front of your ears on either side of your head, these are your largest salivary glands. About 80 percent of salivary gland tumors start in these glands. About 75 percent of these tumors are benign (usually a type called pleomorphic adenomas) and 25 percent are malignant.
- Submandibular glands These are just under your mandible, or jaw bone, about halfway between your chin and your ear. About 10 to 15 percent of salivary gland tumors start here. About half of the tumors arising in these glands are benign and half are malignant.
- Sublingual glands These are in your mouth under your tongue on either side. Tumors are not as common in these glands. The majority of tumors arising in these glands are malignant.
- You also have over 1000 microscopic salivary glands around your head and neck. We call these the minor salivary glands. Tumors in these glands are not common, but when they occur about 25 percent are benign and 75 percent are malignant.
There are many different types of salivary gland tumors, based on the type of cell where the tumor starts:
- Mucoepidermoid carcinoma
- Adenoid cystic carcinoma
- Acinic cell carcinoma
- Adenocarcinoma (either low grade or high grade).
These are the most common examples of malignant tumors, but other types of cancers can occur as well. One way that doctors group malignant salivary gland tumors is by grade. The grade of a tumor is based on how normal the cancer cells look and how quickly they grow or spread.
- Grade 1: Cells look very normal and grow slowly. Outcome tends to be good when doctors can perform a surgical resection (removing the tumor through surgery). Also called low grade or well differentiated.
- Grade 2: Cell appearance and outcome falls between grade 1 and 3. Also called intermediate grade or moderately differentiated.
- Grade 3: Cells look very abnormal and grow or spread quickly. Outcome tends to be poor. Also called high grade or poorly differentiated. Doctors often use radiation therapy in addition to surgery for grade 3 tumors.
Cancer that forms in the glandular tissue that lines certain internal organs and makes and releases substances in the body, such as mucus, digestive juices or other fluids. Most cancers of the breast, pancreas, lung, prostate, colon, esophagus and stomach are adenocarcinomas.
Doctors have not been able to link salivary gland tumors to many risk factors (factors that increase your chance of getting a tumor). In most cases, there is no evidence to tell us what caused the DNA changes in the salivary gland cells that led to a tumor. These factors may increase the risk in some cases:
- Having radiation treatment to the head or neck for other reasons
- Being exposed to certain radioactive substances, such as might happen in some industries
- Working with nickel alloy dust or silica dust
- Eating a diet low in vegetables and high in animal fat.
If your tumor is cancer, your doctor will try to determine the stage. The stage reflects how large the tumor is, whether it has spread and, if it has, how far. There is a specific staging system only for major salivary gland tumors. (Tumors arising in minor salivary glands are often staged in the same manner as for the more common epithelial, or squamous cell, tumors arising in the same location.)
Stage I: The tumor is no larger than 2 centimeters (cm) in diameter. It is only within the salivary gland. It is not invading nearby tissue, and it has not spread anywhere else.
Stage II: The tumor is between 2 cm and 4 cm. It is only within the salivary gland. It is not invading nearby tissue, and it has not spread anywhere else.
Stage III: This stage applies in either of these cases:
- The tumor is larger than 4 cm and/or is invading nearby tissue and possibly one lymph node that is less than 3 cm in size and is located on the same side of the neck as the tumor, but it has not spread anywhere else in the body.
- The tumor is less than 4 cm and has spread to one lymph node that is less than 3 cm in size and is located on the same side of the neck as the tumor, but it has not spread anywhere else in the body.
Stage IVA: This stage applies in either of these cases:
- The tumor is 6 cm or larger in size. It may or may not have spread to nearby tissue, including invading the facial nerve, and to one lymph node that is less than 3 cm in size and is located on the same side of the neck as the tumor, but it has not spread anywhere else in the body.
- The tumor is any size, and it has spread to nearby tissue, including invading the facial nerve, and to one or more lymph nodes that are less than 3 cm in size, and are located on either side of the neck.
Stage IVB: This stage applies in either of these cases:
- The tumor is larger than 6 cm in size or has spread to the skull bones, has surrounded the carotid artery, and/or has invaded the facial nerve. It may have spread to multiple lymph nodes on either side of the neck.
- The tumor is any size, may have spread to adjacent tissues, and has spread to at least one lymph node that is greater than 6 cm in size.
Stage IVC: The tumor is any size and has spread to distant sites in the body. It may also have spread to nearby tissue and lymph nodes.
Symptoms that might occur if you have a salivary gland tumor include:
- A lump or ongoing pain in your face, neck, or mouth
- A difference in the size or shape of your face or neck from one side to the other
- Numbness or weakness somewhere in your face.
Other conditions besides tumors may cause these symptoms, too. If you have any of these symptoms, see your doctor for an evaluation.
If your doctor thinks you might have a salivary gland tumor, the doctor will ask about your health history and give you a physical exam, with special attention to your salivary glands, mouth, and neck. The doctor may also check for numbness or weakness in your face.
Imaging studies can also help your doctor determine whether you have a tumor and whether it has spread. These include a Computed Tomography (CT) scan, Magnetic Resonance Imaging (MRI) scan, and Positron Emission Tomography (PET) scan.
If your doctor finds a tumor, the next step is to have a biopsy to remove tumor cells and check whether they are cancer, and if so, which type. There are two types of biopsies you may have:
- Fine needle aspiration: Removing some cells and fluid from the tumor using a syringe.
- Excisional biopsy: Making a small incision to remove a piece of the tumor.
- In some cases, the doctor may go directly to the step of doing surgery to remove as much of the tumor as possible rather than removing only a small piece first for a biopsy.