Cytofluorometric evaluation of nuclear DNA content distribution in renal neoplasms treated by conservative surgery

The prognostic value of nuclear DNA content in 21 patients who underwent conservative surgery for renal tumors was the object of a retrospective study. Cytofluorometric evaluation of nuclear DNA content distribution was performed on smears obtained from 50-micron thick histologic sections prepared with the Hedley technique, using a Leitz MPVII microspectrophotometer. The DNA indexes were plotted in the form of frequency histograms. DNA measurements were repeated by a cell image analysis system (CAS 200; Becton Dickinson) in 16/21 cases. Nuclear DNA content was diploid in 12 cases, triploid in 4, tetraploid in 2 and multiclonal in 3. No statistically significant correlation was found between ploidy and tumor stage and size, using Kendall's tau test, while there was a significant correlation between tumor ploidy and nuclear grade (p < 0.01). Excluding 2 postoperative deaths, with an average follow-up of 54 months, tumor diffusion was observed in 2 patients (1 with multiclonal and 1 with triploid DNA content) and a local recurrence in a patient with a triploid tumor. Of the remaining 16 no evidence of disease (NED) cases, 10 have a diploid DNA tumor content, 2 diploid, 2 tetraploid and 2 multiclonal. It is concluded that even after conservative surgery for renal neoplasms a diploid DNA content is a favorable prognostic factor. A completely negative prognostic impact of nondiploid tumors is not confirmed, since although all three negative events occurred in this group, there are also 4 NED patients with respectively 70, 46, 43 and 40 months' follow-up.