['Pretreatment clinical staging of prostatic adenocarcinoma is important due to the increasing use of nonsurgical treatment options. Using multivariate analysis we assessed the predictive value of biopsy cores positive for cancer as a percent of all cores obtained as well as the percent surface area of needle cores involved with tumor for determining tumor volume and pathological stage at radical prostatectomy. Candidate variables for the multivariate model included patient age, clinical disease stage, serum prostate specific antigen (PSA) and Gleason score of cancer in the needle biopsy.', 'We reviewed prostate needle biopsy findings in 207 consecutive patients who subsequently underwent radical retropubic prostatectomy. Each biopsy specimen was assessed for tumor involvement by calculating the percent of cores positive for cancer, percent surface area involved in all cores and Gleason score. Initial serum PSA and preoperative clinical disease stage were incorporated with biopsy results into a multivariate model to determine the parameters most predictive of pathological stage and tumor volume at radical retropubic prostatectomy.', 'Of the 207 patients 152 (73.4%) had organ confined cancer and 55 (26.6%) had extraprostatic extension (pathological stages T2 and T3 or greater, respectively). Preoperative clinical staging information was available in 195 cases, in which disease was clinically confined and not confined in 184 (94.4%) and 11 (5.6%), respectively. Needle biopsy revealed a surface area of cancer ranging from less than 5% in 69 patients (33.3%) to 90% (mean 16, median 10). Univariate analysis demonstrated that the risk of extraprostatic extension was predicted by preoperative serum PSA (p = 0.027), the percent of cores and percent of surface area positive for cancer (p <0.0001), and Gleason score (p = 0.0009). Clinical stage approached significance (p = 0.071). Multivariate analysis showed that the percent of positive cores (p = 0.0003), initial serum PSA (p = 0.005) and Gleason score of cancer in the needle biopsy (p = 0.03) were the only parameters that jointly predicted pathological stage (T2 versus T3). Percent of tumor surface area involvement in the needle biopsies did not add any more information after the percent of positive cores was known. Univariate analysis revealed that the percent of cores positive for cancer (Spearman r = 0.52, p <0.0001), Gleason score (Spearman r = 0.34, p <0.0001) and initial serum PSA (Spearman r = 0.24, p = 0.003) were predictive of log tumor volume at radical prostatectomy, while clinical stage was not (rank sum test p = 0.14). On multivariate analysis the percent of positive cores (p <0.0001), Gleason score (p <0.0001) and initial serum PSA (0.0033) were the only variables that jointly were predictive of tumor volume.'] Is the percent of cores positive for cancer in prostate needle biopsy specimens strongly predictive of tumor stage and volume at radical prostatectomy?