Leukoplakia and carcinoma in situ synchronously associated with invasive oral/oropharyngeal carcinoma in Rochester, Minn., 1935-1984.

Previous investigations into the association between oral/oropharyngeal carcinoma and clinical white patches (leukoplakia) have noted that the latter lesion is found adjacent to malignancies in 10% to 100% of all carcinomas of this site. This is an unacceptable variation in results and probably relates more to the referral biases inherent in hospital-based studies than to any other factor. The present population-based study, which is relatively free of selection bias, demonstrates that 62%, 36%, and 18% of invasive carcinomas of the labial vermilion, oral cavity proper, and oropharynx, respectively, have leukoplakia lesions of immediately adjacent mucosal surfaces. Only 7% of invasive carcinomas have juxtaposed carcinoma in situ, whereas another 2% have severe epithelial dysplasia. Mucosal carcinomas associated with leukoplakias appear to be smaller, more mature histologically, and more likely to be only superficially invasive; such carcinomas present with fewer metastases at diagnosis and provide a better prognosis than similar carcinomas not associated with leukoplakia.