A series of esophageal lesions, mild, moderate and severe dysplasia,
carcinoma in situ (CIS), early and advanced
squamous cell carcinoma were induced in rats with N-
methyl-N-amylnitrosamine (MAN). To evaluate the biological nature of each lesion, the ploidy level was estimated by microspectrophotometrical measurement of cell nuclear
DNA content.
DNA distribution patterns were classified into types I, II, III and IV, according to the degree of dispersion and the peak modal value on the
DNA histogram. The incidences of type III of high ploidy in early
cancer, CIS and severe dysplasia were 3/11 (27.3%), 5/13 (33.3%) and 4/16 (25%), respectively. On the other hand, in moderate and mild dysplasia, 15/16 (93.8%) and 20/21 (95.2%) were low ploidy (types I and II), respectively. The mean
DNA content of advanced and early
cancer, CIS and severe dysplasia were 3.88c, 3.34c, 3.24c and 3.13c, respectively, while those of moderate and mild dysplasia were near diploid, showing 2.67c and 2.51c, respectively. These findings indicate that the biological nature of severe dysplasia may be considered as serious a lesion as
cancer, in terms of
DNA analysis. Cytophotometric
DNA analysis
aids the evaluation of various degrees of dysplasia and
carcinoma of the esophagus.