Analysis of DNA ploidy using fresh frozen tissues of head and neck squamous cell carcinomas

The DNA ploidy of fresh frozen tissues of head and neck squamous cell carcinomas was determined by flow cytometry to investigate whether DNA ploidy is correlated with various clinical and pathological parameters. The subjects were 51 patients who had been treated radically by our department. The DNA ploidy pattern was classified into three types, diploid, single aneuploid and multiploid, according to the DNA index and the DNA histogram. This is our original classification. No particular correlation could be detected between the DNA ploidy pattern and sex, age, primary tumour site or disease stage. The degree of tissue differentiation tended to be poorer in aneuploid tissues than in diploid tissues. The efficacy of chemotherapy was higher in aneuploid cases than in diploid cases. The recurrence rate was significantly lower in diploid cases than in multiploid cases. When disease stage, degree of histological differentiation, efficacy of the chemotherapy and the DNA ploidy pattern were subjected to multivariate analysis for correlation with the prognosis, the DNA ploidy pattern showed the highest correlation. The results suggest that the DNA ploidy as analyzed by flow cytometry can be used as an important prognostic factor.