Mouth cancer, also known as oral cancer, is where a tumour develops in the lining of the mouth. It may be on the surface of the tongue, the insides of the cheeks, the roof of the mouth (palate), or the lips or gums.
Tumours can also develop in the glands that produce saliva, the tonsils at the back of the mouth, and the part of the throat connecting your mouth to your windpipe (pharynx). However, these are less common.