Oral cancers develop on the tongue, on the tissue lining the mouth and gums, under the tongue, at the base of the tongue, and the area of the throat at the back of the mouth.Mouth cancer, also known as oral cancer or cancer of the oral cavity, is often used to describe a number of cancers that start in the region of the mouth. Oral cancer includes cancers of the lips, tongue, cheeks, floor of the mouth, hard and soft palate, sinuses, and pharynx . Oral cancer is cancer that develops in the tissues of the mouth or throat. It belongs to a larger group of cancers called head and neck cancers. A sample of tissue or cells is always needed to confirm a cancer diagnosis before treatment is started. Several types of biopsies may be used, depending on each case.