quote:

Genetic Factors: Genetic factors involved in the development of cancer include:

Hereditary predisposition: An individual with a hereditary predisposition for cancer is a person with an increased likelihood of developing cancer due to inherited genes. These inherited genes make body cells more sensitive to environmental factors, such as sunlight and tobacco, and, therefore change normal body cells into cancer cells.
Oncogenes: Cancers can be derived from mutations in genes that change cell growth patterns. These genes are called oncogenes. Such a mutation in an oncogene can convert ordinary body cells into cancer cells. Cancers caused by oncogenes are not inherited. To date, scientists have discovered more than 100 oncogenes, and several oncogenes have been associated with cancers of the head and neck.
Tumor suppressor genes: Normal tumor suppressor genes are anti-cancer genes that slow down or stop growth of normal body cells. Mutations of tumor suppressor genes can also cause the development of oral and pharyngeal cancers.
Tobacco and Alcohol: Use of tobacco and alcohol are the major risk factors for developing oral cancer. Tobacco and alcohol contains substances that are carcinogenic or promote cancer. Cigarettes smoke and substances in smokeless tobacco have received considerable attention as carcinogens that promote oral cancer. Studies also indicate that smoking in combination with consumption of alcohol produces an even greater risk for oral cancer than use of either substance alone.

Radiation: Radiation of high dosage and prolonged duration can produce cancer. There is no evidence that routine dental X-rays are carcinogenic, especially with today's high speed, low dosage machines.

Traumatic irritation: Prolonged irritation from broken teeth, rough dental restorations, and ill-fitting dentures are considered a possible causes for oral cancer.

Viruses: Some viruses can cause cancer in human cells. Studies have indicated a link to oral cancer with infections from herpes simplex type- I virus, Epstein-Barr virus, and human papillomavirus.

quote:

Conclusions: These data suggest that genetic factors are important in the aetiology of head and neck cancer, in particular for patients with multiple primary cancers. Given the prolonged exposure of these subjects to carcinogens, these genetic factors may have a role in modifying carcinogen activity or in host resistance to carcinogens. Inherited factors may be important in persons with environmentally induced cancers.