Oral cancer is a disease in which malignant (cancer) cells form in the lips, mouth, or throat.

Oral cancer may form in any of three main areas:

• Lips.
• Oral cavity, which includes:
  • The front two thirds of the tongue.
  • The gingiva (gums).
  • The buccal mucosa (the lining of the inside of the cheeks).
  • The floor (bottom) of the mouth under the tongue.
  • The hard palate (the front, bony part of the roof of the mouth).
  • The retromolar trigone (the small area behind the wisdom teeth ).
• Oropharynx, which includes:
  • The middle part of the pharynx (throat) behind the mouth.
  • The back one-third of the tongue.
  • The soft palate (the back, soft part of the roof of the mouth).
  • The side and back walls of the throat.
  • The tonsils.

Most oral cancers start in squamous cells (thin, flat cells ) that line the lips, oral cavity, and oropharynx. Cancer that forms in squamous cells is called squamous cell carcinoma. Lesions on the mucous membranes (the lining of the mouth and throat), including leukoplakia (an abnormal white patch of cells) and erythroplakia (an abnormal red patch of cells), may develop into squamous cell carcinoma.

Oral cancer is more common in men than in women.

Most patients with oral cancer are men. However, the number of women in the United States diagnosed with tongue cancer has increased greatly over the past 20 years.

In Western countries, such as the United States, the most common areas for oral cancer are the tongue and the floor of the mouth. In parts of the world where chewing tobacco or betel nuts is common, oral cancer often forms in the retromolar trigone and buccal mucosa.