Head and neck cancer is a term used to describe a number of different malignant tumors that develop in or around the throat, larynx, nose, sinuses, and mouth (see below).
Most head and neck cancers are squamous cell carcinomas. This type of cancer begins in the flat, squamous cells that make up the thin layer of tissue on the surface of the structures in the head and neck. Directly beneath this lining, which is called the epithelium, some areas of the head and neck have a layer of moist tissue, called the mucosa. If a cancer is limited to the squamous layer of cells, it is called carcinoma in situ. If the cancer has grown beyond this cell layer and moved into the deeper tissue, then it is called invasive squamous cell carcinoma.
If a head and neck cancer starts in the salivary glands, the tumor will usually be classified as an adenocarcinoma, adenoid cystic carcinoma, or mucoepidermoid carcinoma.