Evaluation of DNA Ploidy Combined with a Cytometric Proliferation Index of Imprints from Core Needle Biopsies in Prostate Cancer

Abstract

Objective: To evaluate if DNA ploidy analysis with a proliferation index (PI) derived from DNA cytometry of imprints from core needle biopsies predicts disease progression in patients with prostate cancer. Methods: Touch imprints were done on a consecutive series of core needle biopsies taken by the same urologist from 240 patients with suspected prostate cancer, 137 (46%) of whom were found to have prostate cancer and included in the study. Scattered cells to the right of the image cytometry (ICM) ploidy-establishing peak, the S-phase fraction, and those in the G2M area of the ICM DNA histograms, were counted in percent of the total number of tumor cells, this value being designated the ICM PI. Based on previous results in archival fine needle aspiration material, the following classification was used: DNA group I, diploid tumor with a low PI; DNA group II, diploid tumor with an intermediate PI and tetraploid tumor with a low or intermediate PI, and DNA group III, diploid or tetraploid tumor with high PI and all tumors with an aneuploid pattern. Results: Correlation was found to exist between DNA groups I–III and Gleason score (GS) (p < 0.0001), T-stage (p = 0.006), M-stage (p = 0.009) and disease progression (p < 0.0001). Among the 39 patients who had curative treatment and GS 5–7, the progression-free survival rate was 100% in DNA group I, as compared with only 38% in DNA group II and 55% in DNA group III within the follow-up period (p = 0.008). Conclusion: DNA ploidy combined with a PI derived from image cytometry of imprints from core needle biopsies yields additional prognostic information in patients with GS 5–7. Diploid tumors with a low PI (DNA group I) are associated with a low risk of disease progression.