Zonal origin of localized prostate cancer does not affect the rate of biochemical recurrence after radical prostatectomy

OBJECTIVE: To investigate whether transition zone (TZ) prostate cancers demonstrate different rates of biochemical recurrence after radical prostatectomy compared to peripheral zone (PZ) cancers. METHODS: In 1262 consecutive patients treated with radical prostatectomy, computerized planimetry defined tumour origin as either TZ tumours (>70% TZ location) or PZ. Kaplan-Meier and multivariate Cox regression models tested the association between zonal origin and the rate of biochemical recurrence (prostate-specific antigen >0.1ng/ml and rising). We used the Harrell's concordance index to quantify the accuracy of various Cox regression models. RESULTS: TZ prostate cancers were diagnosed in 115 patients (9.1%). Biochemical recurrence was recorded in 16 TZ and in 201 PZ prostate cancers patients. In multivariate Cox models, the rate of biochemical recurrence was not significantly different between TZ and PZ prostate cancers (p=0.4). Combined multivariate predictive accuracy of biochemical recurrence predictions was 81.2% accurate when zonal origin was included versus 81.0% when zonal origin was omitted. CONCLUSIONS: The zonal origin of prostate cancers does not affect the rate of biochemical recurrence after radical prostatectomy.