Genetic Abnormalities in Oral Leukoplakia and Oral Cancer Progression

The cancer progression of oral leukoplakia is an important watchpoint in the follow-up observation of the patients. However, potential malignancies of oral leukoplakia cannot be estimated by histopathologic assessment alone. We evaluated genetic abnormalities at the level of copy number variation (CNV) to investigate the risk for developing cancer in oral leukoplakias.

The current study used 27 oral leukoplakias with histological evidence of dysplasia. The first group (progressing dysplasia) consisted of 7 oral lesions from patients with later progression to cancer at the same site. The other group (non- progressing dysplasia) consisted of 20 lesions from patients with no occurrence of oral cancer and longitudinal follow up (>7 years). We extracted DNA from Formalin-Fixed Paraffin-Embedded (FFPE) samples and examined chromosomal loci and frequencies of CNVs using Taqman copy number assays.

CNV frequently occurred at 3p, 9p, and 13q loci in progressing dysplasia. Our results also indicate that CNV at multiple loci-in contrast to single locus occurrences-is characteristic of progressing dysplasia.

This study suggests that genetic abnormalities of the true precancer demonstrate the progression risk which cannot be delineated by current histopathologic diagnosis.