Impact of uni- or multifocal perineural invasion in prostate cancer at radical prostatectomy

Background

Aim of this study was to correlate perineural invasion (PNI) with other clinical-pathological parameters in terms of prognostic indicators in prostate cancer (PC) cases at the time of radical prostatectomy (RP).

Methods

Prospective study of 288 consecutive PC cases undergoing RP. PNI determination was performed either in biopsy or in RP specimens classifying as uni- and multifocal PNI. The median follow-up time was 22 (range, 6-36) months.

Results

At biopsy PNI was found in 34 (11.8%) cases and in 202 (70.1%) cases at the time of surgery. Among those identified at RP 133 (46.1%) and 69 (23.9%) cases had uni- and multi-PNI, respectively. Presence of PNI was significantly (P<0.05) correlated with unfavorable pathological parameters such higher stage and grade. The percentage of extracapsular extension in PNI negative RP specimens was 18.6% vs. 60.4% of PNI positive specimens. However, the distribution of pathological staging and International Society of Urological Pathology (ISUP) grading did not vary according to whether PNI was uni- or multifocal. The risk of biochemical progression increased 2.3 times in PNI positive cases was significantly associated with the risk of biochemical progression (r=0.136; P=0.04). However, at multivariate analysis PNI was not significantly associated with biochemical progression [hazard ratio (HR): 1.87, 95% confidence interval (CI): 0.68-3.12; P=0.089]. Within patients with intermediate risk disease, multifocal PNI was able to predict cases with lower mean time to biochemical and progression free survival (chi-square 5.95; P=0.04).

Conclusions

PNI at biopsy is not a good predictor of the PNI incidence at the time of RP. PNI detection in surgical specimens may help stratify intermediate risk cases for the risk of biochemical progression.