FLOW CYTOMETRIC ANALYSIS OF DNA CONTENT IN PARAFFIN-EMBEDDED TISSUE IN HEAD AND NECK CANCER

Flow cytometric analysis of DNA content from paraffin-embedded material has become an important diagnostic and prognostic method in clinical pathology and investigative oncology.We analyzed nuclear DNA content in order to detect possible alternations in DNA histogram as an indicator of malignant potential and carcinogenic process of head and neck tumor.DNA histo- grams were evaluated by three parameters;DNA aneuploidy, S+G2M%:rate of S and G2+M phase cells as a parameter for growth kinetics, and polyploid%:rate of more than tetraploid cells as a parameter of nuclear atypia.We took a simple method for the selection of tumor area in paraffin blocks using a consecutive section stained with hematoxylin-eosin as a diagnostic guideline.This technique can be used either to enrich the sample to be analyzed with aimed area or to analyze histopathologically different compartments of the tumor.We compared the result of fresh and fixed specimens in 20 materials.DNA aneuploidy was found in both specimens of the same two carcinomas and there was a close relationship between them in S+G2M%(p<0.01) and polyploid%(p<0.05).We studied two cases of maxillary carcinoma with coexisting inverted papilloma as precancer- ous lesion.In one case S+G2M% and polyploid% were 16%, 1.15% in nasoparanasal papilloma, 20.5%, 4.0% in papilloma with atypia, and 33%, 8.25% in carcinoma, respectively.In the other case those were 3%, 0.1% in transitional papilloma, 8%, 0.9% in inverted papilloma, and 13%, 4.0% in carcinoma, respectively.There was positive correlation between these two parameters and histopathological grade.Finally we analyzed nuclear DNA content from fixed specimens in three groups;33 papillomas, 15 maxillary carcinomas and 23 normal epithelia.Mean values of S+G2M% and polyploid% were as follows:2.1%, 2.6% in normal epithelia, 19.6%, 8.9% in papillomas, and 34.8%, 18.1% in carcinomas.There was statistical significance between three groups(p<0.01).DNA aneu- ploidy was only found in 6 of 15 carcinomas(40%).The results demonstrated that S+G2M% and polyploid% were significantly compared with the histopathological grade of atypia and DNA aneuploidy was a marker of carcinoma.We suggest that DNA histogram is a good indicator for biological activity and that the increased S+G2M% and polyploid% may indicate carcinogenic process.We also suggest that tumor progression may lead to acquired genetic variability and DNA aneuploidy.