Perineural invasion as a predictor of biochemical outcome following radical prostatectomy for select men with clinically localized prostate cancer

Purpose: The presence of perineural invasion on the prostate needle biopsy specimen has been suggested to be an independent predictor of prostate specific antigen (PSA) outcome following radical prostatectomy. We evaluated the clinical use of perineural invasion at biopsy for predicting time to PSA failure following radical prostatectomy after controlling for established prognostic factors. Materials and Methods: A prospective evaluation using a Cox regression multivariate analysis of 750 men with clinically localized or PSA detected prostate cancer was performed to evaluate the ability of PSA, biopsy Gleason score, perineural invasion on the needle biopsy specimen and the percent of positive prostate biopsies to predict PSA outcome following radical prostatectomy. Results: Multivariate analysis demonstrated that the presence of perineural invasion on the needle biopsy specimen provided additional information regarding 5-year PSA outcome (82% versus 95%, p = 0.04) for patients who were in the low risk group. This difference in PSA outcome could be explained by higher rates of positive surgical margins (25% versus 17%, p = 0.07). Patients whose prostate needle biopsy contained perineural invasion and who had the corresponding neurovascular bundle resected had a significantly lower positive margin rate (11% versus 100%, p = 0.001) compared to those who had the neurovascular bundle spared. The presence of perineural invasion on biopsy was not a significant predictor of PSA outcome following radical prostatectomy for patients in the intermediate or high risk group. Conclusions: Resection of the neurovascular bundle on the side corresponding to location of perineural invasion on the biopsy may decrease the positive surgical margin rate and improve outcome for low risk patients.