Needle biopsy DNA ploidy status predicts grade shifting in prostate cancer

DNA ploidy analysis of prostate needle biopsy specimens was performed to de termine whether ploidy status could predict tumor grade shifting at radical prostatectomy. The paired needle biopsy and radical prostatectomy specimen s from 111 randomly selected men with prostate cancer were obtained from th e surgical pathology files of the Albany Medical Center Hospital. The origi nal tumor grades were assigned by a staff of 12 surgical pathologists accor ding to the Gleason system. Tumors with original Gleason scores less than o r equal to 6 were classified as low grade, and tumors with scores of greate r than or equal to 7 were considered high grade. DNA ploidy analysis was pe rformed on the needle biopsy specimens using the CAS 200 image analyzer (Be cton Dickinson Immunocytometry Systems, Mountain View, CA, USA) on Feulgen stained 5-mu m tissue sections. There were 88 diploid and 23 nondiploid cas es. Thirty-eight of 111 (34%) of cases had grade shifting from needle biops y to radical prostatectomy specimens. Of 89 low-grade needle biopsy cases, 28 (31%) were upgraded at radical prostatectomy. Of 22 high-grade needle bi opsy cases, 10 (45%) were downgraded to low grade at radical prostatectomy. Of the 28 low-grade needle biopsy specimens that were upgraded at radical prostatectomy, 19 (68%) featured an aneuploid histogram and 9 (32%) were di ploid. Nineteen of 28 (68%) of aneuploid low-grade tumors an needle biopsy became high-grade at radical prostatectomy. Nine of 10 (90%) diploid high-g rade tumors at needle biopsy became low-grade at radical prostatectomy. Of the 38 cases in which ploidy and grade were incongruous, 28 (74%) had grade shifting. In a multivariate regression analysis, a high-grade Gleason scor e on radical prostatectomy specimens correlated significantly with needle b iopsy ploidy (p = 0.0001) but not with needle biopsy grade (p = 0.15). The sensitivity of the needle biopsy grade in the detection of high-grade tumor s on radical prostatectomy was 30%, and the specificity was 86%. The sensit ivity of ploidy status in the prediction of high grade at radical prostatec tomy was 78%, and the specificity was 96%. With a prostate-specific antigen (PSA) level of > 0.4 ng/ml as the indicator of post-radical prostatectomy disease recurrence on a subset of 106 patients, on univariate analysis, dis ease recurrence was predicted by needle biopsy ploidy (p = 0.001) and radic al prostatectomy grade(p = 0.04) but not by needle biopsy grade (p = 0.39). On multivariate analysis, needle biopsy DNA ploidy status independently pr edicted disease recurrence (p = 0.002), whereas needle biopsy and prostatec tomy grade did not. These results indicate that DNA ploidy analysis of need le biopsy specimens of prostate cancer predicts grade shifting, that it is a more sensitive and specific indicator of final tumor grade at radical pro statectomy than is the original needle biopsy grade, and that ploidy status independently predicts postoperative disease recurrence.