Which putatively pre-malignant oral lesions become oral cancers? Clinical relevance of early targeting of high-risk individuals.

Oral squamous cell carcinomas continue to be a group of diseases with high mortality and increasing incidence rates, particularly among young individuals. This is a paradox finding, since most oral cancers are preceded - even by several years - by readily detectable mucosal changes, most often white or red patches (leukoplakias and erythroplakias, respectively). However, only a small fraction of leukoplakias or erythroplakias are related to cancer development, and the challenge has been to identify the high-risk lesions. From the vast literature on molecular markers in oral pre-cancer, no reliable prognostic marker for risk assessment in putatively pre-malignant lesions has emerged. For this reason, a wait-and-see approach has been adopted for this group of lesions. Recently published data point to gross genomic aberrations (DNA aneuploidy) as a tool for targeting patients at particular risk for future cancerous lesions in the oral cavity. Thus, DNA aneuploidy signalled a very high risk for subsequent development of carcinomas in a wide range of lesions from the oral mucous membrane, ranging from oral leukoplakias to oral erythroplakias and even including lesions that had been explicitly defined as being without a malignant potential by a group of trained pathologists. As an extension of research in oral pre-malignancies, the enzyme cyclooxygenase-2 (COX-2) seems to be enhanced specifically in high-risk oral lesions, as defined by the aberrant DNA content of their lesions. These data strongly indicate that COX-2 inhibitors (coxibs) should be investigated as chemopreventive agents in patients identified to be at high risk of developing oral cancer.