Flow cytometric analysis of the DNA content in primary and metastatic lesions of colorectal cancer.

We investigated and compared the DNA content between primary and metastatic lesions from 30 colorectal cancer cases. The findings were only diploid in 2 cases (6.7%) and only aneuploid in 18 cases (60.0%). On the whole, the DNA ploidy agreed in 20 cases (66.7%) between both lesions. In the 18 cases with only aneuploid tumors in both lesions, the DNA index tended to be larger in the metastatic lesions than in the primary lesions. In contrast, a variation in the DNA ploidy was observed in 10 cases (33.3%). These findings show that DNA ploidy tends to remain stable during metastasis in many cases of colorectal cancer, although the DNA index did tend to be larger in metastatic lesions than in primary lesions. The existence of intertumoral heterogeneity in the DNA ploidy also shows that specimens should be investigated from both lesions in order to obtain more accurate information on the tumor and its biological behavior.