[Prognostic role of perineural invasion in prostate biopsy]

Despite tumour cell dissemination through the intraprostatic nervous system being considered as a prostate cancer progression mechanism, the significance of perineural invasion in prostate biopsies to predict extraprostatic extension and its use as a potential prognosis factor is controversial.

Retrospective study carried out at an institution on 208 patients treated with radical prostatectomy (January 2007 - July 2010) in which the presence of perineural invasion and the Gleason score in the preoperative biopsy were determined, as well as the clinical stage and the pre-surgery PSA. We classified the patients in risk groups in accordance with the D'Amico classification. We performed bivariate and multivariate statistical analyses to establish the correlations between the different variables.

We objectified PNI in 18.3% of the prostate biopsies. 71% of the prostatectomy specimens with perineural invasion presented extraprostatic extension in the previous biopsy against 23.1% when this was not found (p<0.0001) and 47% of the cases showed positive margins with PNI, against 18.3% without perineural invasion (p<0.0001). In fact, in the multivariate analysis, perineural invasion proved to be an independent risk factor in the presentation of extraprostatic extension and positive margins in the prostatectomy specimen.

The presence of perineural invasion is a useful prognostic factor for predicting extraprostatic extension and the involvement of surgical margin in the radical prostatectomy specimen. We believe that determining it may be a useful tool for improving preoperative diagnosis and planning treatment.