The Impact of Prostate Cancer Zonal Origin on Pathological Parameters at Radical Prostatectomy and Subsequent Biochemical Failure.

PURPOSE: We assessed the impact of prostatic zone tumor origin on pathological prognostic features and subsequent biochemical outcomes after radical prostatectomy.

MATERIALS AND METHODS: A total of 7,051 patients who underwent radical prostatectomy between September 1998 and December 2016 in Western Australia were divided into a high grade group, defined as Gleason sum 4 + 3, 8 and 9 or greater and ISUP (International Society of Urological Pathology) groups 3, 4 and 5, and a low grade group, defined as Gleason sum 6 or less and 3 + 4, and ISUP groups 1 and 2. The t-test and the Pearson chi-square test were used to evaluate differences between transition zone and peripheral/central zone cancer. The Kaplan-Meier method with the log rank test was used to determine differences in biochemical recurrence-free survival at 5 years in patients with high grade disease. Univariate and multivariable Cox proportional hazard regression analyses were performed. Model calibration was determined by the internal validation method.

RESULTS: High grade transition zone cancer was associated with significantly increased prostate specific antigen, tumor volume and incidence of positive surgical margins but a lower incidence of intraductal carcinoma, extraprostatic spread, seminal vesicle invasion, lymph node involvement and biochemical failure after radical prostatectomy. Patients with low grade prostate cancer had excellent biochemical recurrence-free survival regardless of tumor origin. The high grade multivariable model had a c-index of 0.78 and improved predictive accuracy, particularly for high grade transition zone disease.

CONCLUSIONS: Transition zone tumor origin independently and positively impacts biochemical outcomes of high grade prostate cancer. A high grade postoperative prognostic model including transition zone tumor origin as an independent predictor was developed and predictive accuracy was significantly improved in patients with high grade, transition zone disease.