DNA-measurements on formalin-fixed, paraffin-embedded squamous cell carcinomas from different ENT-regions

DNA measurements were performed on formalin-fixed, paraffin-embedded squamous cell carcinomas, using the method of Hedley et al. Ultrasonication was sometimes necessary after enzymatic disintegration to dispose of residual cytoplasm. The isolated nuclei were stained with Hoechst 33258. DNA measurements were performed using a rapid system for static fluorometry (FLUORA-programme). The method proved to be highly accurate. The mean CV of the stem cell peaks from different tumours was 5.3. There was no difference between material less or more than 5 years old (mean CVs 5.2 and 5.5 respectively). RNase treatment had no effect and was therefore not considered necessary. The proliferative activity was calculated by computer assuming a rectilinear distribution of S-phase cells. Because routinely paraffin-embedded material can be used, DNA analysis can be performed on tumour material where the clinical outcome is known, in order to evaluate certain DNA variables.