Zonal location of prostate cancer: Significance for disease-free survival after radical prostatectomy?

Objectives. To analyze the zonal location of prostate cancer as a possible predictive feature of progression-free survival after radical prostatectomy. Methods. Prostate cancers were divided into three groups according to the percentage of cancer volume (70% or more, 31% to 69%, and 30% or less) located in the transition zone (TZ). In a total of 307 patients, 5-year progression-free probabilities were estimated for different clinical and pathologic tumor characteristics using the Kaplan-Meier method. With emphasis on the percentage of cancer volume located in the TZ, univariate and multivariate analyses were performed to calculate their prognostic significance in predicting progression-free probability. Results. Prostate cancer with 70% or more, 31% to 69%, and 30% or less of the cancer volume in the TZ was found in 17.3%, 6.8%, and 75.9% of the patients, respectively. Patients with tumors with 70% or more of the cancer volume in the TZ had a significantly (log-rank P=0.0402) greater rate of biochemical cure than those with 30% or less (82.1% versus 66.2%). The increasing percentage of cancer volume located in the TZ was significantly (P=0.0258) associated with a greater progression-free probability in univariate analysis, but did not retain independent significance (P=0.5748) in multivariate analysis. Instead, pathologic stage (P<0.0001), lymph node involvement (P=0.0189), and Gleason score on prostatectomy specimen (P=0.0023) were independent prognosticators. Conclusions. The location of prostate cancer in the TZ was associated with a greater overall biochemical cure rate after radical prostatectomy. However, it was not an independent prognosticator on multivariate analysis. Therefore, the knowledge about zonal location of prostate cancer offers no advantage over the well-established prognostic factors in predicting disease recurrence.