Most lip and oral cavity cancers start in squamous cells, the thin, flat cells that line the lips and oral cavity. These are called squamous cell carcinomas. Cancer cells may spread into deeper tissue as the cancer grows. Squamous cell carcinoma usually develops in areas of leukoplakia (white patches of cells that do not rub off).
Lip and oral cavity cancer is a type of head and neck cancer.
SEER Cancer Stat Facts: Oral Cavity and Pharynx Cancer. National Cancer Institute. Bethesda, MD, http://seer.cancer.gov/statfacts/html/oralcav.html