DNA ploidy in colorectal cancer, heterogeneity within and between tumors and relation to survival

Flow cytometry was used to study the incidence of aneuploidy and to determi ne the significance of multiple sampling from colorectal tumors, DNA ploidy pattern has been proposed as a supplementary prognostic marker, but discre pancies in findings are major, DNA clonal heterogeneity, defined as two or more DNA aneuploid stemlines in the same tumor, is well established. Howeve r, most studies have been based on only one biopsy from each tumor. In our study multiple biopsies were taken from 163 patients (88 males and 75 femal es) electivly operated for colorectal cancer, Tumor cells were harvested by fine needle aspiration from fresh frozen biopsies sampled at different sit es of each tumor. DNA aneuploidy was detected in tumors from 145 patients (89%), and 18 patie nts (11%) had a solitary DNA diploid cell population. In a 79 month follow- up period 105 patients had died. Statistical analysis showed that distincti on between diploidy and aneuploidy did not predict survival. However, group ing subpopulations into DNA diploid plus near diploid (DNA index (DI) 0.97- 1.15), DNA aneuploid with all aneuploid subpopulations in the interval 1.15 -2.06, and DNA aneuploid with subpopulations with DI < 0.97 and/or DI > 2.0 6, showed a significant difference in survival in a Cox multivariate analys is including Dukes' stage P = 0.049 comparing the second group to the first and P = 0.01 comparing the third group to the first, In 21 (13%) patients only one subpopulation was found, 57 (35%) had two, 44 (27%) had three, and 41 (25%) had four or more different subpopulations. The association of DNA ploidy to survival is shown to be dependent on the number of biopsies anal ysed. Cytometry (Comm. Clin. Cytometry) 38:293-300, 1999. (C) 1999 Wiley-Li ss, Inc.