Prognostic Significance of Capsular Invasion and Capsular Penetration in Japanese Men with Prostate Cancer Undergoing Radical Retropubic Prostatectomy

Background: The objective of this study was to evaluate the prognostic significance of the local extent of prostate cancer in relation to the prostate capsule. Patients and methods: The series included 110 patients with prostate cancer who underwent radical retropubic prostatectomy in a single institution in Japan between September 1997 and February 2003. The resected prostatectomy specimens were investigated by whole-mount step section at 5 mm intervals. According to the pathological findings, patients were divided into three groups as follows: 44 with localized cancer tissues apart from the capsule (group A), 33 with capsular invasion without penetration (group B) and 33 with capsular penetration (group C). Several clinicopathological factors of these patients were analyzed in relation to the capsular status. Results: The capsular status was significantly related to lymph node metastasis, seminal vesicle invasion and tumor volume. During the observation period (median: 22 months), biochemical recurrence occurred in 13 patients (three in group A, two in group B and eight in group C), and the biochemical-recurrence free survival rate in group C was significantly lower than those in groups A and B. Patients with capsular penetration at more than one site were at significantly increased risk for biochemical recurrence compared with those with a single capsular penetration; however, there was no significant relationship between the location of capsular penetration and biochemical recurrence. Furthermore, the biochemical recurrence-free survival rate was significantly associated with capsular penetration, seminal vesicle invasion and tumor volume among various factors examined, nevertheless these three factors were not independent predictors for biochemical recurrence on multivariate analysis. Conclusion: Subclassification of patients undergoing radical prostatectomy according to the capsular status provides valuable prognostic information; that is, patients with capsular penetration, particularly at more than one site, have a significantly higher risk of biochemical recurrence than those without capsular involvement or with capsular invasion alone. Thus, careful follow-up and if necessary, additional treatment should be considered in cases demonstrating capsular penetration.