Tobacco use in all its forms is number one on the list of risk factors. At least 75% of those diagnosed with oral cancer are tobacco users. When you combine tobacco with heavy use of alcohol, your risk is significantly increased, as the two act synergistically. Those who both smoke and drink, have a 15 times greater risk of developing oral cancer than others. There are some possible links to young men who use "smokeless" chewing or spit tobacco. Promoted as a safer alternative to smoking, it has in actuality, not proven to be any safer to those who use it.
Exposure to ultraviolet radiation Cancer of the lip is one oral cancer whose numbers have declined in the last few decades. This is likely due to the increased awareness of the damaging effects of prolonged exposure to sunlight, and the use of sunscreens for protection.
Radiographs (X-rays) regularly taken during examinations, and at the dental office, are safe, but remember that radiation exposure is accumulative over a lifetime. It has been implicated in several head and neck cancers.
Biological factors include viruses and fungi, which have been found in association with oral cancers. The human papilloma virus, particularly HPV16 and 18, have been implicated in some oral cancers. HPV is a common, sexually transmitted virus, which infects about 40 million Americans. There are about 80 strains of HPV, most thought to be harmless. But 1% of those infected, have the HPV16 strain which is a causative agent in cervical cancer, and now is linked to oral cancer as well. This is thought to be due to the increase in oral sex.
There are other risk factors which have been associated with oral cancers, but have not yet been definitively shown to participate in their development. These include lichen planus, an inflammatory disease of the oral soft tissues.
There are studies which indicate a diet low in fruits and vegetables. Conversely, one high in these foods may have a protective value against many types of cancer.