Ploidy and proliferation patterns in colo-rectal adenocarcinomas related to Dukes' classification and to histopathological differentiation. A flow-cytometric DNA study.

The cellular DNA pattern in 66 colo-rectal adenocarcinomas was studied by means of flow-cytometric DNA analysis. The degree of ploidy and the proportion of cells in S-phase were related to the clinical stage according to Dukes' classification and to the histological differentiation. Multiple cell populations were found in about 60 per cent of the tumours but more frequently in advanced clinical stages. According to the DNA index the cell populations were bimodally distributed with one peak in the diploid-peridiploid region and one peak in the tri- to tetraploid region. In the second group there was a higher frequency of more advanced tumours as compared to the first. The proportion of cells in S-phase was higher in pure diploid tumour cell populations of all clinical stages as compared to normal mucosa but lower as compared to peridiploid and aneuploid cell populations with high DNA index. High as well as low S-phase values may occur in all clinical stages, but a significant higher mean value was found for Dukes' C compared to Dukes' B tumours. Distant metastases occur at all DNA indices and with various S-phase values. In conclusion, tumours of different clinical stages and histological differentiation may be subdivided according to DNA index, to the existence of single or multiple cell populations and to the proportion of cells in S-phase. The biological significance of this subdivision can only be evaluated by means of clinical follow-up.