Squamous cell carcinoma and precursor lesions of the oral cavity: epidemiology and aetiology.

People diagnosed with malignant neoplasms often feel afraid and alone. However, cancer is largely an avoidable disease, and studies have shown that more than two-thirds of cancer deaths may be prevented through lifestyle modification, early detection and effective treatment. The World Health Organization (WHO) estimates that nearly 12.7 million new cases and 7.6 million cancer deaths occurred worldwide in 2008 (27). Oral cancers are malignant neoplasms that affect the structures or tissues of the mouth. They may be a primary lesion that originated in the mouth, a metastasis from a distant site, or an extension from an adjoining site. In quoting detailed epidemiological data, it is necessary to distinguish between these origins, and to ascertain which structures are included, e.g. the vermillion borders of the lips are sometimes included and sometimes not. Globally, oral cancer is the eighth most common cause of cancer-related deaths, although many people are unaware of its existence (91). Of these oral cancers, more than 90% are squamous cell carcinomas arising in the mucous membranes of the mouth and oropharynx.