Oral and throat cancer appears to occur as a result of situations that damage the cells in your mouth and throat. Using tobacco and excessive alcohol consumption can damage these tissues. The combination of smoking or chewing tobacco and excessive drinking creates a much higher risk of oral and throat cancer. Excessive exposure to ultraviolet light, chewing your lips and the inside of your mouth and wearing loose fitting dentures can damage and result in irritation to cells inside your mouth. Damage to cells may cause them to malfunction and to reproduce rapidly as cancer cells.

• Nicotine dependence

A variety of factors that you can control increase your risk of oral cancer. These include:

• Use of tobacco. Tobacco can damage cells in the lining of the oral cavity and upper throat. Smokers are six times more likely to develop oral or upper throat cancers than nonsmokers are. About 90 percent of people who develop these cancers use some form of tobacco. Tobacco use is more prevalent among men, and oral cancer is twice as common in men as in women.

• People who use smokeless or chewing tobacco are at even higher risk of cancers of the cheek and inner surface of the lips. Aside from oral and throat cancers, using smokeless tobacco can cause other serious health problems, including cancer of the esophagus, larynx, stomach and pancreas, and gum disease, high blood pressure and cardiovascular disease. When you use smokeless tobacco, your body absorbs more than just nicotine. It absorbs a number of cancer-causing substances, including arsenic and formaldehyde.

• Excessive alcohol consumption. Alcohol also can damage cells inside your mouth and upper throat. About 75 percent to 80 percent of people with oral and upper throat cancers are frequent drinkers of alcohol. The combination of alcohol and tobacco use significantly increases the risk.

• Chronic irritation from jagged tooth surfaces or poorly fitting dentures. Irritation caused by the dentures doesn't appear to be a factor in oral cancer. However, poorly fitting dentures can trap particles of tobacco and alcohol, which may irritate the lining of your mouth.

• Prolonged exposure to ultraviolet light. Too much ultraviolet light can damage the cells on your lips and increase your risk of lip cancer.

• White patches on the tongue or inside of the cheek (leukoplakia). Most of the time leukoplakia is not dangerous. But leukoplakia can be serious, as some of the patches may show early signs of cancer, and a large percentage of cancers of the mouth occur in areas in which leukoplakia is adjacent. Leukoplakia may result from a variety of causes, including smoking or chewing tobacco products, ill-fitting dentures, a rough spot on an adjacent tooth, or cheek-biting.