Prediction of extracapsular extension of prostate cancer based on systematic core biopsies

OBJECTIVE: To evaluate the clinical utility of transrectal ultrasound-guided systematic sextant or octant biopsies for the prediction of extracapsular extension (ECE) at radical prostatectomy. MATERIAL AND METHODS: We performed a retrospective analysis of 84 patients who underwent preoperative staging and transrectal ultrasound-guided systematic sextant (n=60) or octant (n=24) biopsy. The presence of ECE was correlated with the number of positive biopsies on each side of the prostate by chi(2) analysis. Sensitivity, specificity and positive and negative predictive values were calculated for both positive (two or three positive biopsies per side) and negative (none or one positive biopsy per side) test results. The number of positive cores was thereafter combined with two other parameters: prostate-specific antigen (PSA) level and Gleason score. RESULTS: ECE was evidenced at radical prostatectomy in 24% of patients (20/84). chi(2) analysis demonstrated a significant correlation between the number of positive biopsies and the presence of ECE. Analysis of the 168 prostate sides and dominant sides revealed that systematic needle biopsies had positive predictive values of 46.7% and 37%, respectively and negative predictive values of 89% and 94%, respectively. Use of a combination of parameters (biopsy Gleason score > or =7 vs <7; PSA >10 vs < or = 10 ng/ml; and >1 positive core vs none or one positive cores) identified patients at high or low risk of ECE. At the extremes, none of the 10 patients in the low-risk group had ECE at radical prostatectomy, compared to 77% of those in the high-risk group. CONCLUSION: The probability of ECE at radical prostatectomy can be accurately predicted based on the number of positive sextant and octant biopsies, either alone or in combination with other parameters.