DNA HETEROGENEITY IN PROSTATIC ADENOCARCINOMA - A DNA FLOW CYTOMETRICMAPPING STUDY WITH WHOLE ORGAN SECTIONS OF PROSTATE

Background. The degree of DNA heterogeneity varies between tumors aris ing at different sites. The presence of a significant degree of variab ility within a given tumor may result in problems in the interpretatio n of DNA flow cytometric findings. This study evaluated the degree of DNA heterogeneity in prostatic adenocarcinoma. Methods. A total of 122 3-mm punch biopsy specimens were evaluated from single representative whole organ sections from nine cases of prostate cancer (range, 4-18 samples per case; mean, 12 samples; median, 14 samples). Individual pu nch biopsy specimens were graded and reviewed to confirm the presence of carcinoma and processed for DNA ploidy analysis. Results. Assessabl e histograms, defined as having a coefficient of variation of the dipl oid G0/G1 peak of 7.5% or less, were available for ill (91%) of the sa mples. Of the nine cases studied, five (56%) showed heterogeneity in t he DNA pattern (diploid plus aneuploid, n = 1; diploid plus tetraploid , n = 2; and diploid plus tetraploid plus aneuploid, n = 2). All four cases having a homogeneous DNA content were DNA diploid in all samples . In those cases with a heterogeneous pattern, the areas having abnorm al DNA patterns could not be predicted by histologic pattern or grade. Conclusions. From this study, the authors conclude that a significant degree of DNA heterogeneity exists within individual cases of prostat ic adenocarcinoma, and this may be an important confounding factor in DNA ploidy studies.