The prognostic value of zonal origin and extraprostatic extension of prostate cancer for biochemical recurrence after radical prostatectomy

Objective: To investigate the influence of the zonal origin of prostate cancer and extraprostatic extension on biochemical recurrence (BCR). Patients and methods: We included 638 consecutive patients undergoing radical prostatectomy between 2005 and 2015 who did not receive neoadjuvant/adjuvant therapy. The largest lesion was defined as the index tumor. We categorized each patient into the transition zone (TZ) or peripheral zone (PZ) group based on the lesion where the index tumor existed. Differences in the BCR defined as increasing prostate-specific antigen rate between groups were examined by Kaplan-Meier analysis and the Cox proportional hazards model. Results: There were 293 (46%) patients with TZ cancer and 345 (54%) with PZ cancer. TZ cancer was significantly associated with a higher prostate-specific antigen (P = 0.012), lower biopsy positive core rate (P = 0.020), lower pathological Gleason score (P = 0.017), lower pathological stage (P = 0.002), and lower rate of seminal vesicle invasion (P = 0.002). During a median follow-up period of 59 months, 79 patients (12%) developed BCR. In the entire cohort, the PZ origin (hazard ratio: 1.68, P = 0.033) and extraprostatic extension were independent risk factors for BCR. The 3-, 5-, and 7-year BCR-free survival rates of patients with pT3a TZ cancer were 89%, 88%, and 86%, respectively, which were significantly better than those of patients with pT3a PZ cancer (80%, 74%, and 62%, P = 0.012), but were similar to those of the pT2 cancer cohort (92%, 91%, and 90%, P = 0.376). Conclusion: TZ cancer had more favorable pathological characteristics and oncological outcome than PZ cancer especially in pT3a cases.