Intratumoral heterogeneity in DNA ploidy of bladder carcinomas

In order to investigate whether DNA ploidy in a single area of a tumor could be representative of the entire tumor, flow-cytometric DNA analysis was performed for multiple samples (an average of 7 samples) obtained from the same tumor in 9 cases of transitional cell carcinoma of the urinary bladder. The incidence of DNA aneuploidy was 88.9% (8 out of 9 cases) and, furthermore, in 7 of these, intratumoral regional heterogeneity in DNA ploidy was evident. With high frequency, bladder carcinoma consisted of heterogeneous cell populations with different ploidy. There were 2 cases in which the tumor consisted of mixed subpopulations of diploid and aneuploid clones which were located in different parts of the same tumor. In such cases, an aneuploid line could not have been detected in a single specimen from the tumors.