Prediction of perineural invasion and its prognostic value in patients with prostate cancer.

Purpose: The prognostic significance of perineural invasion by prostate cancer is debated. We investigated the association between perineural invasion and clinicopathological factors and the effect of perineural invasion on survival in patients with prostate cancer.
Materials and Methods: A total of 361 patients with prostate cancer without any neoadjuvant therapies prior to surgery from 1999 to 2010 were analyzed retrospectively. Whole-mount sections of surgical specimens from all patients who underwent radical prostatectomy were evaluated. Positive perineural invasion was defined as infiltration of cancer cells in the perineurium or neural fascicles. The relationship of perineural invasion with clinicopathological features and prognosis of prostate cancer was studied. We also researched preoperative factors that were associated with perineural invasion.
Results: Perineural invasion in a prostatectomy specimen (PNIp) was positive in 188 of 361 patients (52.1%). In the multivariate analysis of the preoperative variables, PNIp was related to the primary Gleason grade (p=0.020), the number of positive cores (p=0.008), and the percentage of tumor cells in positive cores (p=0.021), but not to perineural invasion of a prostate biopsy. In the evaluation between PNIp and pathologic findings of the prostatectomy specimen, PNIp was related to the Gleason score (p=0.010), T-stage (p=0.015), and lymphovascular invasion (p=0.019). However, by multivariate analysis, the PNIp was not an independent prognostic factor of biochemical serum recurrence (p=0.364) or cancer-specific survival (p=0.726).
Conclusions: PNIp was significantly related to biologically aggressive tumor patterns but was not a prognostic factor for biochemical serum PSA recurrence or cancer-specific survival in patients with prostate cancer.