[DNA-ploidy and proliferation in metastatic neuroblastoma]

Nuclear DNA contents of tumor cells were measures by fluorescence cytophotometry in bone marrow and touch preparations of 26 children with neuroblastoma, registered in the NBL79 study of the German Pediatric Oncology society. In all cases tumor cells were found to have a higher DNA-content as compared to the normal diploid (2c) DNA-value of granulocytes in the same preparation. Average ploidy values of the histograms of bone marrow metastases were in the tetra- to hypertetraploid (4c-5c) range and showed unimodal distribution in the majority of cases. In the primary tumors there was also a wide distribution of DNA-values in the aneuploid range. A bimodal distribution with stemlines at 2,5c and 5c was found in a stage I, grade I, differentiated primary tumor. Various ploidy patterns found at different sites in the large tumor mass of a newborn might be interpreted as an expression of different degrees of differentiation within the same tumor. In 2 of 4 patients where primary tumor and metastatic lesions could be examined there was a higher ploidy in the 5c to 6c, or even in the 8c range in the metastatic cell population. It appears, thus, that clonal evolution of tumor cells occurs during growth and spread of neuroblastoma.