[Flow cytometry in prostate cancer. Evaluation of its feasibility for biopsy specimens and correlation with grading]

Pathologic staging and grading are the most important prognostic factors in prostatic cancer. Unfortunately, pathologic staging needs to be evaluated by surgical procedures; moreover, the proposed grading systems are largely based upon subjective histopathologic evaluations. In recent years, these problems have been approached with flow cytometry (FCM). The present study evaluates the significance of DNA ploidy of prostatic carcinoma assessed by FCM.

Microscopic slides from 132 core needle biopsies and 22 surgical specimens of prostatic carcinoma were reviewed and classified according to Gleason's score modified by Epstein et al. Formalin-fixed, paraffin-embedded tissue samples were prepared for FCM evaluation using standard techniques. Adequate histograms were obtained from 113 biopsies (85.6%) and from all the surgical specimens (100%).

Among the 113 biopsy specimens, a statistically significant correlation was found between DNA ploidy and Epstein's grading, since high-grade neoplasms accounted for 40.38% of non-diploid cases and only for 21.33% of diploid cases (chi square = 5.8; p = 0.05). Moreover, tetraploid tumors were defined as a separate FCM category with an absolute prevalence (65.52%) of non-high grade neoplasms (chi square = 5.9; p = 0.05). Although not submitted to statistical analysis, data collected from surgical specimens showed similar distribution.

DNA ploidy assessment by FCM is a viable procedure in the majority of needle biopsy tissue samples of prostatic carcinoma; it may produce prognostic parameters with greater objectivity than conventional histologic grading.