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Histologic types: Carcinomas account for 96% (although some studies are as low as 90%) of all oral cancers, most are squamous cell carcinomas from the oral surface and the remainder is derived from the salivary glands. Sarcomas account for about 4% of the malignancies in the oral region.

Age and Sex: Age is an important risk factor. More than 95% of cases occur in people 40 years or older. The peak incidence is the sixth decade, average age of 63. The estimated risk of developing oral cancer continues to increase with age. Although men are affected twice as often today, the proportion of women among those with oral cancer have dramatically increased during the past fifty years from a male to female ratio of 6:1 to 2:1. In recent years, there is some concern that oral cancer may be increasing young adults, especially cancer of the tongue. It is too soon to know if this is a "real trend".

Sites: The tongue, oropharynx and floor of the mouth are the most common sites. Of cancers of the tongue, 53% occur on the anterior two thirds (oral tongue) and 47% on the base of the tongue. For cancers of the oral tongue, nearly three fourths are localized and for cancers of the base of the tongue, more than three fourths are regional (spread to lymph nodes) at the time of diagnosis. Pain is the most common first complaint followed by "a lump". The incidence of lip cancer has declined over several decades from the most common form of oral cancer to less than 8% of new cases.

Stage and Survival: Approximately 53% of oral cancer patients survive five years or longer. Patients with regional disease (lymph node spread) account for about 60% of all newly diagnosed cases and present at a late(r) stage. Though treatment has improved the quality of life for many patients, improved survival is attributable to early diagnosis. Past progress in early diagnosis has leveled off during the last two decades. Early detection remains a valuable part of efforts to improve survival. Improvements in treatment have had a positive affect on the quality of life during survival but little impact on the length of survival.

Race and Genetics: Oral cancer incidence in the United States is 9.9 cases per 100,000 African American males; nearly twice the rate of 5.0 cases per 100,000 for white males. An oral cancer incidence among African American females is higher than for white females by 30% (2.4:1.8 cases respectively) but not nearly as high as their male counterparts. Neither an inherited trait nor family aggregation has been shown for oral cancer. There is no specific gene or genetic test predictive of oral cancer. However, the risk of head and neck cancer is increased in those with rare genetic syndromes such as Bloom's syndrome as well as persons with immunologic abnormalities such as AIDS.

Multiple Cancers: Having developed an oral cancer, patients are at risk of a second synchronous primary estimated at 15%. The risk of a second primary is highest for people who smoke (drink). The second primary is often in the oral cavity (nearly 50%) but the lung and esophagus are also frequent sites. Risk of a second metachronous primary is estimated at 4% per year and higher for those who continue to smoke (drink).

Etiologic Risk Factors: Advancing age, male sex and African American racial type has been mention earlier as factor that appear to increase the risk of oral cancer. Important additional factors are tobacco use and alcohol abuse. In one study, men who were heavy smokers (two plus packs a day) had an increased risk of developing oral cancer of eight times that of a nonsmoker of the same age. For men that abused alcohol (six plus ounces of alcohol a day) the risk of oral cancer was similar; about an eightfold increase compared to non-drinking males of the same age. For those who both smoked heavily and drank excessively, the risk was estimated to be 149 times greater than for non-smokers/non-drinkers. Use of spit tobacco (smokeless) is associated with verrucous carcinomas. In a study of women in North Carolina, there was an estimated fifty fold increase in gingival and buccal mucosa cancers (mostly verrucous carcinomas) in regular snuff dippers. Although some concern has been expressed about the regular use of alcohol containing mouthwash, a 1996 FDA panel was unable to establish any association with an increased risk of oral cancer.

Association with other conditions: There is an association with cirrhosis of the liver when the cirrhosis is alcohol induced. Syphilis, once thought to predispose to tongue cancer, has been largely discounted. Oral lichen planus (OLP), especially if it is of the chronic erosive (ulcerative) type has been reported as a possible risk factor. The rate of OLP associated malignancy has ranged from 0.4-5.6%. A causal relationship has not been established and OLP is not currently designated as a precancerous lesion. However, it is recommended that all patients with OLP be carefully evaluated and reexamined periodically. Although poor oral hygiene and wearing dentures have been speculated as risk factors, of the studies to date, none have shown any causal relationship. There is no evidence to indicate the prudent use of periodic, routine diagnostic dental radiographs increase the risk of oral cancer. Numerous studies have compared communities with and without fluoridated drinking water and there is no evidence that fluoridation poses any increased risk of cancer.

Viruses: Both herpesviruses and papillomaviruses are known to have oncogenic potential and can be found in the mouth. Herpes simplex type 1, 2, 6, and 8 and EBV have been studied with respect to the possibility of being factors in oral cancer. Other than the close association of EBV with Burkitt's lymphoma (African jaw lymphoma), no causal association exists between these viruses and oral cancer. Some, but not all, oral cancers contain HPV at a higher rate than normal oral mucosa. Some evidence of HPV infection in proliferative verrucous leukoplakia suggests that it might be important in transformation. However, HPV is quickly lost from most oral cancers unlike cervical cancers where it persists. Conclusions about the possible role of HPV in oral cancer remain uncertain.