Cancers of the salivary glands are much less common than noncancerous growths. The most common salivary gland cancer is mucoepidermoid carcinoma, which can form in a small (minor) salivary gland on the roof of the mouth or as a lump in one of the large (major) salivary glands, either under or behind the lower jaw.
(See also Overview of Mouth, Nose, and Throat Cancers.)
Doctors do a biopsy (removal of a tissue specimen for examination under a microscope) of any salivary gland they suspect may be cancerous. If the biopsy shows cancer, doctors then do imaging tests, such as computed tomography (CT) and magnetic resonance imaging (MRI), to see the extent of the cancer. Because some salivary gland cancers can spread widely, doctors may also do imaging tests of the lungs, liver, bones, and brain.