Grades and Types of Salivary Gland Cancers
Grades of Salivary Cancers
Salivary gland cancers are classified in the following grades:
- Low grade (well-differentiated): Low-grade tumors look very much like normal salivary gland cells. They tend to grow slowly and have a good outcome.
- Intermediate grade (moderately-differentiated): Intermediate-grade tumors have an appearance and outlook that is between low and high.
- High grade (poorly-differentiated): High grade tumors look quite different from normal cells and often grow and spread quickly. The outlook (prognosis) for these cancers is usually not as good as for lower-grade cancers.
Mount Sinai treats all types of salivary gland cancer. Some of the more common types of salivary gland cancers include:
- Mucoepidermoid carcinoma: Most mucoepidermoid carcinomas 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 they can also be intermediate or high grade.
- Adenoid cystic carcinoma: Adenoid cystic carcinoma is the most common type of cancer in the minor salivary glands. It is usually slow growing and often appears to be a low-grade tumor. It is very hard to completely get rid of and often comes back after surgery, sometimes many years later.
- Adenocarcinomas: Adenocarcinoma is a term used to describe cancers that start in gland cells (cells that normally secrete a substance). These tumors tend to be high grade and may have a less favorable outcome. The group of tumors includes oncocytic carcinoma and salivary duct carcinoma.
- Acinic cell carcinoma: Most acinic cell carcinomas start in the parotid gland. They tend to be slow growing and are usually low grade.
- Polymorphous low-grade adenocarcinoma: These cancers tend to start in the minor salivary glands. They are low grade and usually curable.
- Epithelial-myoepithelial carcinoma: This rare tumor tends to be low grade, but it can come back after treatment or spread to other parts of the body.
- Malignant mixed tumors: Also known as carcinoma ex pleomorphic adenoma, this tumor usually develops from a neglected benign mixed tumor (pleomorphic adenoma). It occurs mainly in the major salivary glands and is uncommon. Both the grade of the cancer and how far it has spread (stage) are important in predicting the outcome of this cancer.
- Squamous cell carcinoma: This cancer occurs mainly in older men. It can develop after radiation therapy for other cancers in the area. When this pathology is identified in the parotid gland, it is important to investigate whether it represents a metastasis from a skin malignancy. This type of cancer tends to have a poorer outlook.