Lack of intratumoral heterogeneity in DNA ploidy pattern of hepatocellular carcinoma

Abstract

Background : From biological and clinical perspectives, it is important to clarify tumor heterogeneity. This study was aimed to investigate whether or not intratumoral heterogeneity of DNA ploidy pattern exists in hepatocellular carcinoma (HCC). Methods : Using fresh materials resected from 31 untreated patients, DNA ploidy was analyzed at different sites of the same HCC by means of flow cytometry. The tumor size ranged from 1.7 to 25.0 cm. Results : There was no case in which euploid and aneuploid HCCs coexisted in the same tumor. The DNA ploidy pattern was euploid in 15 and aneuploid in 16 instances. Of 15 euploid tumors, the areas analyzed were all diploid in 12 and tetraploid in 2 but diploid/tetraploid in 1. Among 16 aneuploid tumors, the DNA indices (DI) at different sites were similar in 9, but apparently, different aneuploid subclones coexisted in 7 cases. The incidence of DI heterogeneity in aneuploid HCCs was similar between small (<5 cm) and large (≧5 cm) tumors; 3 of 7 (42.9%) versus 4 of 9 (44.4%). Conclusions : It is assumed that euploid and aneuploid HCCs develop in their own ploidy pattern and that the evolution of aneuploid subpopulations from euploid HCC is rare, but new aneuploid subclones can evolve from aneuploid HCC due to increased instability of its karyotype.