Deoxyribonucleic acid ploidy and cell cycle events in benign colonic epithelium peripheral to carcinoma

DNA ploidy and cell cycle phases of benign human colonic epithelium peripheral to adenocarcinoma were analyzed by flow cytometry in 188 prospective cases. Human colonic epithelium was shown to be diploid with a mean DNA index (DI) of 1.01. The G0G1 compartment accounted for nearly 93% of the cells with the remainder in the S and G2+M phases. Parallel [3H]thymidine uptake on selected cases confirmed the relatively low proliferative activity of colonic mucosa. The DNA index and the cell cycle compartments exhibited no correlation to the ploidy, Dukes' stage, size, and anatomical location of the corresponding malignant tumors. Approximately 25% of the benign samples possessed DI values outside of the diploid range (defined as the mean +/- sd). Analysis of these apparently hypo- (less than 0.92) and hyper- (greater than 1.09) diploid, histologically normal samples in terms of cell cycle kinetics and their relationship to Dukes' stage, location, distance, and the ploidy of the tumor showed no correlation. The only characteristic differentiating these "aberrant" samples from diploid benign tissue was variation in DI possibly due to differences in fluorochrome binding or accessibility to DNA. Whereas these results indicate some degree of variability in the DNA content of benign colonic epithelia, neither DI nor cell cycle kinetics appear to be affected by the presence of a malignant tumor and are not representative of either the ploidy or pathologic stage of the corresponding colonic carcinoma.