Pathologic parameters and flow cytometric ploidy analysis in predicting recurrence in carcinoma of the prostate

Recurrence of prostate cancer following radical prostatectomy is determined by the extent of local disease. Tumor volume and grade have improved our ability to predict extraprostatic extension, but tumors of intermediate volume and grade vary in their biologic behavior. To assess the prognostic significance of DNA ploidy, we performed flow cytometry in 85 patients with prostate cancer volumes > 4 cm3. Post-radical prostatectomy serum prostate-specific antigen was used to prove recurrence of cancer. Mean follow-up was 35 months (median 31 months). 26 patients (30%) had diploid histograms, 55 (65%) non-diploid histograms. In 4 cases (5%) the histograms were uninterpretable. Tumor volume and percent of Gleason grades 4 or 5 separated the recurrent from nonrecurrent groups in a highly significant manner (p < 0.001). When tested alone, ploidy had no ability to predict recurrence (p = 0.26). However, in a subset of patients with 4-8 cm3 of cancer with < 30% Gleason grade 4 or 5 tumor, ploidy conferred significant additional prognostic information (p < 0.005).