The DNA content in cancer and dysplasia in chronic ulcerative colitis

The nuclear DNA content was determined with a cytophotometric technique in colonic mucosa of 15 patients with long-standing ulcerative colitis. The epithelial lesions were classified into inactive colitis, low grade and high grade dysplasia and adenocarcinoma. The histogram pattern varied between narrow unimodal in quiescent colitis, broad unimodal in low grade dysplasia with some hypertetraploid values in three cases (27%) and aneuploid in 62.5% of the lesions with high grade dysplasia. In well-differentiated adenocarcinoma the histograms were broad unimodal, whereas the curves of moderately and poorly differentiated carcinomas were wider and aneuploid. The technique can be used for a prognostic purpose: in dysplastic lesions, the detection of aneuploidy is important because it is frequently found in the presence of invasion although it does not allow its prediction. Carcinomas with polyploid DNA distribution have a better outcome than tumours with aneuploid distribution.