This consists of lesions involving the lips, gums, palate, buccal mucosa, tongue, floor of the mouth, tonsils, and pharynx.

Epidemiology. Incidence

Mortality

Rates And Ratios

Trend Last Ten Years

Age

Etiology

Epidemiologic studies have clearly established the importance of certain extrinsic factors in the etiology of mouth cancer.

Tobacco

The smoking history of a patient can be of great assistance in screening for cancer of the oral cavity and larynx in asymptomatic individuals. The risk of developing cancer of these sites is 3 times as great in the heavy smoker and 1 1/2 rimes as great in the average smoker as it is in the person who smokes little or not at all. Conversely, cancer of the oral cavity and larynx in the nonsmoking individual is an extreme rarity.

Alcohol

Heavy alcohol consumption results in a considerable increase in the risk of cancer of the oral cavity and larynx in the smoker. It is not known whether this holds true for the nonsmoker. The increased risk inherent in heavy alcohol consumption can be summarized as follows: The risk of developing cancer of the oral cavity is 10 times as great in the heavy drinker (over 6 ounces of whisky or its equivalent per day) as it is in the average or nondrinker.

Pathology

Mouth cancer is almost exclusively of the epidermoid variety. Rather commonly, the malignant lesion is associated with leukoplakia; i.e., the two lesions may occur in different regions of the same epithelial surface, or the cancer may appear to arise from an area of pre-existing leukoplakia. There is little agreement on the clinical and pathologic criteria for the diagnosis of leukoplakia except in its most florid form. It is widely acknowledged, at least in the latter phase, to be a premalignant lesion. Leukoplakia must be differentiated from mucosal plaques associated with lichen planus and lesions resulting from cheek-biting or dental irritation. If one confines the diagnosis to relatively substantial and persistent whitish plaques and correlates the clinical findings with pathologic findings obtained by biopsy, then the term takes on genuine meaning and significance.

A pathologic diagnosis of carcinoma in situ is fairly common in suspicious oral lesions.

Not uncommonly, oral cancer appears to be multicentric in origin; i.e., it arises from more than one area of the oral epithelium at the same time or within a very short interval. Such cancers may often be regarded as evidence of recurrence following treatment when, in fact, they are second primary lesions. Furthermore, if the patient survives long enough, the incidence of second primary lesions in other, more distant areas of the respiratory and upper alimentary tracts is far above the expected; e.g., the number of patients with double or triple primary lesions involving the oral cavity, larynx, lung, and esophagus is quite significant. For example, 14% of patients with cancer of the tongue or tonsil develop second lesions of the head and neck area.

These characteristics may be summarized as follows:

1. Epidermoid pathology

2. Association with leukoplakia and carcinoma in situ

3. Tendency to be multicentric and recurrent

4. Association with second primaries elsewhere in exposed sites

All of the foregoing characteristics of oral cavity cancer lend clinical and pathologic substantiation to the epidemiologic evidence Unking the disease to a carcinogenic factor or factors to which the mucosa is diffusely and chronically exposed.

The most important and common of these is undoubtedly tobacco. Alcohol appears to play a role only when ingestion is quite heavy and prolonged in the person who is also a smoker. The possible secondary roles played by dietary factors, as well as by dental and oral hygiene, require more study and clarification before their true significance can be established.