Aims and background: Both flow cytometric DNA ploidy and proliferative activity have been indicated as potential prognostic indicators in colorectal cancer. Due to tumor biological heterogeneity, these parameters are best assessed with multiple sampling.
Methods: We undertook a prospective study on 52 patients with Duke's D colorectal tumors looking at multiple samples of the primary tumors and liver metastases. DNA ploidy and tumor proliferative activity (derived from proliferating cell nuclear antigen, PCNA FCM expression) were evaluated.
Results: Of primary tumors, 36/52 (69.2%) were aneuploid in at least 1 sample, with a median value of the DNA index of the aneuploid peak of 1.58. On liver metastases, 42/52 (80.7%) patients were aneuploid in at least 1 sample with a median DNA index of the aneuploid peak of 1.64. Identical or nearly identical histograms from different tumor samples were observed in only 18/52 (34.6%) of the primary tumors and in 15/52 (28.8%) of the liver metastases. The PCNA values for primary tumors ranged from 5 to 28% (median value = 16.5%). In the liver metastases, PCNA values ranged from 12 to 38% (median value = 19.8%). Proliferative activity was lower for diploid than for aneuploid tumors. DNA ploidy and PCNA expression of the deep specimen of primary tumors were similar to those of the liver metastasis of the same patient while this concordance was not complete in the case of superficial biopsy specimens.
Conclusions: If correctly performed, FCM techniques allow an accurate analysis of DNA ploidy and proliferative activity and both these measurements can offer considerable potential for a more comprehensive approach to colorectal cancer.