Can ploidy of prostate carcinoma diagnosed on needle biopsy predict radical prostatectomy stage and grade?

Deoxyribonucleic acid ploidy correlates with the biological behavior of prostate carcinoma. However, the usefulness of ploidy on needle biopsies that show prostate cancer has not been established to our knowledge.

We retrospectively determined ploidy on needle biopsies of 159 men with prostate carcinoma treated surgically at Johns Hopkins Hospital. Ploidy was determined by image analysis of Feulgen stained slides. Needle ploidy and Gleason score were compared as prognostic tools in the prediction of grade and stage of subsequent prostatectomy.

Of the 159 cases 98 (62%) were diploid, 16 (10%) tetraploid and 45 (28%) aneuploid. Of the diploid, tetraploid and aneuploid tumors 69, 50 and 44%, respectively, proved to be organ confined. Tetraploid and aneuploid tumors were grouped for the remaining analysis. Needle ploidy correlated significantly with pathological stage (p = 0.003). However, needle Gleason score correlated even more strongly (p <0.001), and on multivariate analysis ploidy was not further predictive of pathological stage once Gleason score was considered. Needle ploidy and Gleason score were predictive of prostatectomy Gleason score (6 or less versus 7 or greater), and on multivariate analysis ploidy was an independently significant predictor of this parameter (p = 0.04). In 13 cases (8%) there was an important grading discrepancy, in which needle ploidy would have accurately predicted prostatectomy grade. However, in 33 cases (21%) needle and prostatectomy Gleason scores were congruent, and needle ploidy did not accurately predict prostatectomy Gleason score.

With accurate needle Gleason grading, ploidy is not helpful in predicting prostatectomy findings. However, ploidy correlates with prostatectomy stage and grade, and may be useful if accurate Gleason grading is a concern.