ABSTRACT
As flow cytometric analysis using paraffin-embedded tissue was developed by Hedley et al in 1983, retrospective study with large amount of archival material was possible. Many literatures reported that the result of paraffin embedded tissue was compatible with that of fresh tissue. We compared the DNA histograms of 26 cases of colorectal adenocarcinoma in which the analysis was done in both fresh and paraffin-embedded tissues. Aneuploidy in fresh and paraffin-embed-ded tissues was 73.0% and 50.0%, respectively. The concordance rate of fresh and paraffin-em-bedded tissues was 76.8% and six interpreters were agreed in 73.0% of the cases. Because flow cytometric DNA analysis using fresh tissues can detect more aneuploid population than in paraffin-embedded tissue, the former is strongly recommeded in DNA ploidy study. Also careful observation using standard criteria may improve the interpretation of DNA histogram.