Methods: 40 patients histologically diagnosed with moderate or severe OED were selected. Twenty lesions had progressed to carcinoma within 8-171months (Mean 54.5), and 20 age, sex and site matched controls that had not progressed after a follow up of 5-20 years. Sections from paraffin embedded blocks were digested and nuclear monolayers were prepared using a cytospin. After Feulgen staining DNA content was analysed by image cytometry (Fairfield Ploidy System) and cases classified as normal (diploid) or abnormal (aneuploid or increased tetraploid populations).
Results: Abnormal DNA content was present 12/20 (60%) of the cases that developed carcinoma, but in only 2/20 (10%) cases that did not progress (Mann-Whitney, p<0.01). Of the 14 cases with abnormal DNA (13 aneuploid, 1 tetraploid), 12 (86%) progressed. The sensitivity and specificity of DNA content as a marker for progression was 0.60 and 0.90 respectively.
Conclusions: The results support recent studies suggesting that lesions with abnormal DNA content are at a high risk of malignant transformation. Analysis of ploidy seems to be an effective test for the malignant potential of oral dysplastic lesions.