Predicting prostate carcinoma volume and stage at radical prostatectomy by assessing needle biopsy specimens for percent surface area and cores positive for carcinoma, perineural invasion, Gleason score, DNA ploidy and proliferation, and preoperative serum prostate specific antigen: a report of 454 cases

BACKGROUND: DNA ploidy analysis of prostate carcinoma is a generally accepted prognostic marker, particularly when tumors are extraprostatic at the time of surgery. In the past decade, the DNA content of prostate carcinoma frequently has been assessed in needle biopsy specimens based on the assumption that ploidy, in conjunction with serum prostate specific antigen (PSA) and Gleason score, provides valuable pretreatment information. METHODS: Between 1995 and 1998, the authors identified a consecutive series of 454 prostate carcinomas, verified by needle biopsies and followed by radical retropubic prostatectomies (RRP). Based on the needle biopsies, DNA ploidy and MIB-I immunostaining were measured by digital image analysis (DIA). The authors also quantified the percent of nuclei in four categories from the DNA histograms. The DIA data were combined with the age of the patient at diagnosis, the serum PSA, Gleason score, percent cores and percent surface area positive for carcinoma, and status of perineural invasion in multivariate models using tumor volume and risk of extraprostatic extension (EPE) at RRP as the outcome variables. RESULTS: Joint predictors of tumor volume at RRP were the percent cores positive for carcinoma (P < 0.0001), serum PSA (P < 0.0001), the percent surface area positive for carcinoma (P < 0.0001), and the percent nuclei classified by DNA quantification to be in the "S-phase" category (P = 0.03). Joint predictors of risk of EPE were the percent cores positive for carcinoma (P = 0.0004), a Gleason score of 7 (P < 0.0001), a Gleason score of 8 or 9 (P < 0.0001), serum PSA (P = 0.006) and perineural invasion (P = 0.02). CONCLUSIONS: After adjusting for traditional prognostic markers, DNA ploidy interpretation and MIB-I quantitation of prostate carcinoma did not appear to jointly predict either outcome variable in the multivariate models. However, a quantitative measure related to both ploidy and proliferation, the percent of nuclei in the putative "S-phase" category from the DIA histograms, was found to jointly predict for tumor volume.