Perineural invasion on prostate biopsy does not predict adverse pathological outcome

The clinical significance of perineural invasion (PNI) on prostate needle biopsy is controversial. The aim of this present study is to determine the role of PNI on prostate biopsy in predicting adverse findings at radical prostatectomy in a recent cohort of screen detected prostate cancer.

We analyzed 470 patients diagnosed with prostate cancer from a prospectively maintained database at Princess Margaret Hospital. Out of the 470 patients diagnosed with prostate cancer, 139 underwent radical prostatectomy. Pathological specimens were examined, and perineural invasion was identified as carcinoma tracking along or around a nerve in the perineural space. We investigated the predictive value of PNI on biopsy with PNI on radical prostatectomy as well as the ability of PNI on prostate biopsy to predict adverse findings at radical prostatectomy.

Perineural invasion was present in 124 (26%) of biopsy specimens diagnosed with prostate cancer and 94 (68%) of those who chose radical prostatectomy. Perineural invasion on prostate needle biopsy was not predictive of radical prostatectomy Gleason score (p = .377), pathological stage (p = .852), extraprostatic extension (p = .258), surgical margin (p = .079), lymphovascular invasion (p = .499), and upgrading (p = .514) or downgrading (p = .208) at radical prostatectomy. The sensitivity, specificity, positive predictive value, and negative predictive value of PNI on biopsy for PNI on radical prostatectomy were 32%, 82%, 79%, and 37% respectively. The Cohen's Kappa correlation coefficient was .11.

Perineural invasion on prostate needle biopsy is not predictive of radical prostatectomy outcome. Furthermore, perineural invasion on biopsy has limited predictive value for perineural invasion at radical prostatectomy.