TOBACCO 

Tobacco use through cigarette smoking and the use of pipes, cigars, and snuff is profoundly implicated in the causation of oral cancer. The risk for smokers versus non-smokers is about 6:1, and the higher the daily number of cigarettes and years smoked, the greater the risk. There are a high number of toxic and carcinogenic compounds that exist in tobacco and its smoke and the level of exposure to these agents is the biggest risk factor. Studies have found that after 3 to 5 years of smoking abstinence, oral cancer risk decreased by about 50%.

ALCOHOL

Heavy alcohol consumption (more than 21 standard drinks in one week) is the 2nd largest risk factor for the development of oral cancer. People who also use tobacco are at especially higher risk. Scientists have found that these substances synergistically interact, increasing each other’s harmful effects. The dehydrating effect of alcohol on oral mucosal cell walls enhances the ability of tobacco carcinogens to permeate mouth tissues; additionally, nutritional deficiencies associated with heavy drinking lower the body’s natural ability to use antioxidants to prevent the formation of cancers.

BETEL NUT AND QUID

Betel nut is used by approximately 10% of the world's population and is common in many Asian countries. It is chewed for its psychoactive stimulant effect, making it the fourth most widely used addictive substance. The WHO classifies betel nut as a carcinogen. Studies have found links between betel nut use and cancer of the mouth and esophagus. It causes oral submucous fibrosis and inflammation in the lining of the mouth and higher risk for oral and esophageal cancer. 

HPV INFECTION

The human papilloma virus (HPV16) is a double-stranded DNA virus that infects the oral mucosa and is a leading cause of oropharyngeal cancer. HPV-positive head and neck cancers typically develop at the back of the throat near the tonsils. The HPV viral life cycle is initiated through microlesions in the epithelium. It happens slowly but can eventually lead to mucosal changes and then cancer. HPV incidence is on the rise and with that, the risk of HPV linked oral cancer.

ULTRAVIOLET LIGHT

Exposure to ultraviolet radiation, usually from sunlight or tanning beds, is known to cause cancer of the lips as well as other skin cancers. Lip cancers are more common among people who work outdoors or have prolonged exposure to the sun. Oral cancer from UV exposure has declined over the last decades, most likely due to the increased awareness of the damaging effects of prolonged exposure to sunlight and the use of sunscreen for protection

IMMUNE SYSTEM SUPPRESSION

The immune system can be weakened after an organ transplant or treatment for an immune system disease. People with a weakened immune system have a higher risk of developing oral cancer, especially lip cancer. The higher risk may be due to taking drugs that suppress your immune system and the body's decreased resistance to fight off disease. People with weakened immune systems are also more likely to get an HPV infection, which increases the risk for oral cancer.

LICHEN PLANUS

Lichen planus is an chronic inflammatory condition that affects mucous membranes inside the mouth. Oral lichen planus may appear as white, lacy patches; red, swollen tissues; or open sores. These lesions may cause burning, pain or other discomfort. The disorder occurs when the immune system mounts an attack against cells of the oral mucous membranes for unknown reasons. Symptoms can usually be managed, but people who have oral lichen planus need regular monitoring because they may be at risk of developing mouth cancer in the affected areas.

LEUKOPLAKIA

Leukoplakia is a condition in which thick, white or grayish patches form usually inside your mouth. It can be caused by chewing tobacco, heavy smoking, and alcohol use. More serious cases may be linked to oral cancer and must be treated promptly. Proliferative verrucous leukoplakia (PVL) is a rare aggressive form of oral leukoplakia. It is strongly associated with the presence of Epstein-Barr virus, a type of herpes virus. Nearly all cases eventually become cancerous at different sites. PVL is usually diagnosed late in the development of leukoplakia, as it takes time to spread to multiple sites. It also has a high rate of recurrence.

INHERITED CONDITIONS

People with the following inherited conditions have a higher risk of developing precancerous changes in the mouth and oral cancer. These develop at a much earlier age than oral cancer caused by other risk factors.

Fanconi anemia is a rare genetic condition that affects the bone marrow so it can’t make enough red blood cells, white blood cells or platelets.

Dyskeratosis congenital is a genetic syndrome that can cause abnormal red blood cells, skin rashes and abnormal fingernails and toenails.