What Is Salivary Gland Cancer?

Minor salivary glands

There are also several hundred minor salivary glands that are too small to see without special lab equipment. These glands are under the lining of the lips and tongue; in the roof of the mouth; and inside the cheeks, nose, sinuses, and larynx (voice box). Tumors in these glands are uncommon, but they are more often malignant than benign. Cancers of the minor salivary glands most often start in the roof of the mouth.

Types of salivary gland cancers

There are many types of salivary gland cancers. Normal salivary glands are made up of different kinds of cells, and cancers can start in any of these cell types. Salivary gland cancers are named according to which cell types they most look like.

Based on how normal the cells look, salivary gland cancers are also often graded (from 1 to 3, or from low to high), The grade of the cancer gives an idea of how quickly it is likely to grow and spread. Also, people with low-grade cancers tend to have better outcomes than those with high grade cancers.

• Grade 1 (also called low grade or well differentiated) means the cancer cells look very much like normal salivary gland cells. They tend to grow slowly and have a good outcome (prognosis).
• Grade 2 (also called intermediate grade or moderately differentiated) means the cancer cells look like those between grade 1 and grade 3 cancers. The outcomes are also between a grade 1 and grade 3 cancer.
• Grade 3 (also called high grade or poorly differentiated) means the cancer cells look very different from normal cells and often grow and spread quickly. The outlook for these cancers is usually not as good as for lower grade cancers.

Mucoepidermoid carcinoma

Mucoepidermoid carcinomas are the most common type of salivary gland cancer. Most start in the parotid glands. They develop less often in the submandibular glands or in minor salivary glands inside the mouth. These cancers are usually low grade, but can sometimes be intermediate or high grade.

Adenoid cystic carcinoma

Adenoid cystic carcinoma is the second most common type of salivary gland cancer, is usually slow growing, and often appears to be low grade when looked at in the lab. Still, it’s very hard to get rid of completely because it tends to spread along nerves. These tumors tend to come back after treatment (usually surgery and radiation), sometimes many years later. The outlook is better if the tumor is smaller.

Acinic cell carcinoma

Most acinic cell carcinomas start in the parotid gland. They tend to grow slower and tend to develop in younger people than most other salivary gland cancers. They are usually low grade, but how far they have grown into nearby tissue is probably a better predictor of a person’s outlook.

Polymorphous adenocarcinoma

These tumors tend to start in the minor salivary glands. They usually (but not always) grow slowly and are mostly curable. They are more common in women than men.

Adenocarcinoma, not otherwise specified (NOS)

When seen in the lab, these cancers have enough features to show that they are adenocarcinomas, but not enough detail to classify them further. They are most commonly found in the parotid glands and the minor salivary glands. These tumors can be any grade. They are often seen in people older than 60 years of age.

Secretory carcinoma (Mammary analogue secretory carcinoma)

These cancers are more often found in minor salivary glands. They tend to be low grade and grow slowly. They can be found equally in men and women.

Rare adenocarcinomas

Several types of adenocarcinoma are quite rare.

Some of these tend to be low grade and people who have them usually have a very good outcome:

• Basal cell adenocarcinoma
• Clear cell carcinoma
• Cystadenocarcinoma
• Sebaceous adenocarcinoma
• Sebaceous lymphadenocarcinoma
• Mucinous adenocarcinoma

Other rare adenocarcinomas are more likely to be high grade and may have a less favorable outcome:

• Oncocytic carcinoma
• Salivary gland duct carcinoma

Malignant mixed tumors

Mixed tumors have more than one type of cancer cell. There are 3 types of malignant mixed tumors:

• Carcinoma ex pleomorphic adenoma (has benign cells and carcinoma cells)
• Carcinosarcoma (has both carcinoma and sarcoma cells)
• Metastasizing mixed tumor

Nearly all malignant mixed tumors are carcinoma ex pleomorphic adenomas. The other 2 types are very, very rare.

Carcinoma ex pleomorphic adenoma develops from a benign mixed tumor (also known as a pleomorphic adenoma). This tumor is found mainly in the major salivary glands. Both the grade of the cancer and how far it has spread (its stage) are important in predicting outcome.

Other rare salivary gland cancers

Several other types of cancer can develop in the salivary glands.

Squamous cell carcinoma: This cancer occurs mainly in older men. It can develop after radiation therapy for other cancers in the area, but most often cancer is spread from a squamous cell cancer of the skin that started in the head and neck area. This type of cancer tends to have a poorer outlook.

Epithelial-myoepithelial carcinoma: This rare tumor tends to be low grade, but it can come back after treatment and/or spread to other parts of the body.

Anaplastic small cell carcinoma: The cells in these tumors have neuroendocrine features. This means the cells get messages from nerves to release certain hormones. These tumors are most often found in minor salivary glands and tend to grow quickly.

Undifferentiated carcinomas: This group of cancers includes small-cell undifferentiated carcinoma, large-cell undifferentiated carcinoma, and lymphoepithelial carcinoma. These are high-grade cancers that often spread. Overall, the survival outlook tends to be poor. Lymphoepithelial carcinoma, which is much more common in Eskimo and Inuit people, is associated with the Epstein-Barr infection and has a slightly better outcome.

Types of benign salivary gland tumors

Most salivary gland tumors are benign, that is, they are not cancer and will not spread to other parts of the body. These tumors are almost never life-threatening.

There are many types of benign salivary gland tumors, with names such as pleomorphic adenoma, oncocytomas, and Warthin tumors.

Benign tumors are almost always cured by surgery. Very rarely, they may become cancer if left untreated for a long time or if they are not completely removed and grow back. It’s not clear exactly how benign tumors become cancers.

Our information about salivary gland cancers does not cover benign tumors.

Other cancers that can affect the salivary glands

These types of cancer are typically not thought of as true salivary gland cancers, either because they start more often in other parts of the body, or because they start elsewhere and then grow into or spread to the salivary glands.

Non-Hodgkin lymphoma

Most non-Hodgkin lymphomas start in lymph nodes. Rarely, these cancers start in immune system cells within the salivary glands. They behave and are treated differently from other types of cancers in the salivary glands. Most lymphomas that start in the salivary glands affect people with Sjögren syndrome (a disorder that causes the immune system to attack salivary gland cells). For more information, see Non-Hodgkin Lymphoma.

Sarcoma

The salivary glands have blood vessels, muscle cells, and cells that make connective tissue. Cancers that start in these types of cells are called sarcomas. These rarely occur in the salivary gland. For more information, see Soft Tissue Sarcoma.

Cancers that spread to the salivary glands

Some cancers, like squamous cell skin cancer or melanoma, might start elsewhere but spread to the salivary glands. These cancers are treated based on where the cancer started.