A disease in which cancerous cells are found in the tissues of the salivary glands. The salivary glands make saliva, the fluid that is released into the mouth to keep it moist and to help dissolve food. Major clusters of salivary glands are found below the tongue, on the sides of the face just in front of the ears, and under the jawbone. Smaller clusters of salivary glands are found in other parts of the upper digestive tract. The smaller glands are called the minor salivary glands.