Prognostic Role of Perineural Invasion in 239 Consecutive Patients with Pathologically Organ-Confined Prostate Cancer

Abstract

OBJECTIVE: The aim of our study was to analyze the role of perineural invasion (PNI) as a predictive parameter of outcome after radical prostatectomy (RRP) in pathologically organ-confined prostate cancer (PCa) and to assess its possible correlation with other well-known prognostic features. PATIENTS AND METHODS: At our institution between January 2000 and December 2007, we prospectively collected data from 251 consecutive patients with pathologically localized PCa after antegrade RRP. In our analysis 239 patients were included. PNI was defined as adenocarcinoma within the perineural space adjacent to a nerve. We evaluated the biochemical progression-free survival rate using the Kaplan-Meier method to establish the correlation between PNI and prognosis, the log-rank test to verify the statistical significance, and χ(2) test to investigate the correlation between PNI and other clinicopathological parameters. RESULTS: We found intraprostatic PNI in 157 patients (65.7%). The PNI rate was 73% (149/204) in pT2b-c vs. 26% (8/35) in pT2a surgical specimens (p < 0.001), and it was 78.5% (73/93) in patients with a Gleason score of 7-10 vs. 57% (84/146) in a Gleason score of 2-6 (p < 0.01). The mean follow-up was 65.4 (median 62, range 24-118) months. Overall, 11/239 (4.6%) patients presented biochemical recurrence after surgery and 7 (63.6%) of these patients showed PNI, but this was not statistically higher than in patients free from progression (150/228, 65.7%). The actuarial biochemical progression-free survival rate for all patients was 96.9 and 93.5% at 60 and 84 months, respectively, and the stratification based on the presence or absence of PNI did not allow us to identify different prognostic groups. CONCLUSIONS: Perineural infiltration frequently takes part in the pathway of extraprostatic extension. In our series, patients with pathological T2 stages and PNI were found to present a higher pT2 stage and Gleason score, even though our early biochemical-free outcome was not significantly higher than in patients without PNI.