Postoperative Biochemical Failure in Patients With PI-RADS Category 4 or 5 Prostate Cancers: Risk Stratification According to Zonal Location of an Index Lesion

Abstract

OBJECTIVE. The objective of our study was to assess postoperative biochemical failure in patients with prostate cancer according to zonal location of an index lesion classified as Prostate Imaging Reporting and Data System version 2 (PI-RADSv2) category 4 or 5. MATERIALS AND METHODS. Consecutive patients (n = 232) with prostate cancer who had PI-RADSv2 category 4 or 5 lesions on MRI and who underwent radical prostatectomy were retrospectively evaluated. We investigated clinical (prostate-specific antigen density), MRI (PI-RADSv2 category of index lesion and zonal location, assessed as peripheral zone [PZ] or transition zone [TZ], of index lesion), and pathologic (tumor volume, tumor grade, and presence of extraprostatic extension) parameters. We analyzed Kaplan-Meier survival curves and the Cox proportional hazards model to assess 2-year biochemical failure-free survival and identify significant parameters associated with postoperative biochemical failure RESULTS. Biochemical failure occurred in 14.2% of patients (33/232). Two-year biochemical failure-free survival of patients with a PI-RADSv2 category 4 or 5 index lesion was 81.3%. For all patients, 2-year biochemical failure-free survival was different according to PI-RADSv2 category (category 4, 86.4%; category 5, 74.5%; p = 0.021) or zonal location (PZ, 75.3%; TZ, 96.8%; p = 0.003). Two-year biochemical failure-free survival in patients with category 4 lesions was similar in patients with PZ lesions (83.1%) and those with TZ lesions (100.0%) (p = 0.072), whereas it was different in patients with category 5 lesions (PZ, 62.0%; TZ, 95.0%; p = 0.002). In multivariate analysis, only zonal location of an index lesion on MRI was associated with biochemical failure (hazard ratio = 0.155; p = 0.012). CONCLUSION. Zonal location of an index lesion on MRI may be a useful imaging bio-marker to predict postoperative biochemical failure.