DETECTION OF PLOIDY IN COLORECTAL TUMORS - A COMPARISON BETWEEN FLOW-CYTOMETRY AND CYTOGENETICS

Parallel investigations of ploidy by flow cytometry and cytogenetics w ere performed in 20 colorectal tumors. Flow cytometry detected an aneu ploidy in 13 tumors with DNA indices ranging from 1.13 to 2.21. The ot her samples exhibited an apparent diploid DNA content. Cytogenetic ana lyses revealed an abnormal chromosome count in 14 cases and a frequent implication of numerical or structural changes in chromosomes 1, 7, 1 2 17, 18, and 20. DNA content evaluated by both techniques was general ly concordant with minor discrepancies not exceeding 10%. In six cases , cytogenetics faded to find the cell populations detected by flow cyt ometry. These results indicate that flow cytometry and cytogenetics ar e reliable and complementary techniques, particularly in near-diploid tumors, where flow cytometry has some difficulties in detecting variat ions from diploidy below to 8%.