Cytometric ploidy and proliferative activity in colorectal carcinoma

Thirty cases of colorectal carcinoma have been evaluated for proliferative activity with the monoclonal antibody Ki 67 and with flow cytometry for ploidy, DNA index and the S-phase fraction. In the series, 30% of tumours were strictly aneuploid, 23.8% tetraploid and 45% diploid: "non diploid" cases accounted for 53.8%. The mean comprehensive values of DNA index, percent S-phase and Ki 67 positive fraction were 1.4%, 11.5% and 50%, respectively. The parameters considered showed no statistically significant correlation with each other or with the common histo-pathologic parameters, such as grading and staging. The prevalent prognostic importance of ploidy compared to DNA index is emphasized, and particular attention is paid to diploid cases with a high growth fraction (S-phase fraction), which could make up an "at risk" category. Therefore, we attempted to identify subsets, within groups of the same histologic stage, with a different evolutive significance in relation to DNA content, percentage of positivity to Ki 67, S-phase fraction and ploidy. With such a multi-parametric approach, particular groups of patients at risk could be defined, which are perhaps more sensitive to specific support therapies.