Probability of extraprostatic disease according to the percentage of positive biopsy cores in clinically localized prostate cancer

Objective: Prediction of extraprostatic disease in clinically localized prostate cancer is relevant for treatment planning of the disease. The purpose of this study was to explore the usefulness of the percentage of positive biopsy cores to predict the chance of extraprostatic cancer. Materials and Methods: We evaluated 1787 patients with localized prostate cancer submitted to radical prostatectomy. The percentage of positive cores in prostate biopsy was correlated with the pathologic outcome of the surgical specimen. In the final analysis, a correlation was made between categorical ranges of positive cores (10% intervals) and the risk of extraprostatic extension and/or bladder neck invasion, seminal vesicles involvement or metastasis to iliac lymph nodes. Student's t test was used for statistical analysis. Results: For each 10% of positive cores we observed a progressive higher prevalence of extraprostatic disease. The risk of cancer beyond the prostate capsule for < 10% positive biopsy cores was 7.4% and it increased to 76.2% at the category 90-100% positive cores. In patients with Gleason grade 4 or 5, the risk of extraprostatic cancer prostate was higher than in those without any component 4 or 5. Conclusion: The percentage of positive cores in prostate biopsy can predict the risk of cancer outside the prostate. Our study shows that the percentage of positive prostate biopsy fragments helps predict the chance of extraprostatic cancer and may have a relevant role in the patient's management.