Flow cytometric DNA analyses of frozen samples from children's solid tumors

Cell ploidy and proliferative activity may be useful to clinicians in treating children with solid tumors. Frozen specimens from children with malignant solid tumors were tested at the time of diagnosis for ploidy and proliferative activity. The flow cytometric DNA histograms were examined to assess the sensitivity of the tumor cell preparation and staining method. All the frozen tumors received (n = 58), from children aged 1 mth to 17 yrs, were analyzed and included in this study. The more common tumors were neuroblastomas (n = 21) and Wilms' tumors (n = 16). The majority of tumors (91%) exhibited a diploid peak from the significant proportion of stromal/epithelial cells in the tumor specimen. The tightness of the diploid G0G1 peaks as measured by their coefficient of variations (CV) produced a mean CV of 2.43% +/- SD 0.62, range 1.3% to 4.6%. The G0G1 CVs from the aneuploid peaks had a mean of 2.34% +/- SD 0.68 with the range 0.5% to 3.7%. There was, however, a proportion of tumors (9%) which showed no normal "diploid" peak on the histogram. These tumor cell suspensions had insignificant numbers of diploid cells. Unless the position of the diploid peak could be identified on the DNA histogram the ploidy result from such tumors would be incorrect. Reference diploid cells can be added to cell suspensions prepared from frozen tumors in order to identify the position of the G0G1 peak. Reference diploid cells cannot be added to single cell preparations from paraffin embedded specimens, therefore making it impossible to define the diploid peak position in these tumors.(ABSTRACT TRUNCATED AT 250 WORDS)