Many clinicians are concerned when a patient comes to them with prostate cancer that has been shown to have perineural invasion (PNI). PNI is defined as the presence of prostate cancer found by biopsy that tracks along or around a nerve within the perineural space.

The presence of PNI has been a concern because of the possible relationship between the presence of perineural invasion and extra-prostatic extension (EPE) of prostate cancer. The neurons in question pierce the prostatic capsule and might allow easy exit of cancer cells from the gland into the capsule

According to Gabriele Cozzi, MD who analyzed retrospective data and having performed a univariate analysis on the data concluded that PNI showed a statistically significant association with pT3 tumors (p < 0.00001).However, Dr. Cozzi added that a main limitation to the analysis was their inability to perform a multivariate analysis; thus the results cannot be considered definitive evidence that PNI alone is predictive of EPE.However they do suggest that the presence of PNI should be considered in the decision making for the treatment of prostate cancer balong with other features, such as Gleason score, PSA, number of positive cores, clinical staging, etc.This is an important concern as recent evidences highlighted the importance of predicting EPE in men with high risk prostate cancer, as Abdollah et al. showed that high-risk prostate cancer benefits the most from radical prostatectomy[fusion_builder_container hundred_percent="yes" overflow="visible"][fusion_builder_row][fusion_builder_column type="1_1" background_position="left top" background_color="" border_size="" border_color="" border_style="solid" spacing="yes" background_image="" background_repeat="no-repeat" padding="" margin_top="0px" margin_bottom="0px" class="" id="" animation_type="" animation_speed="0.3" animation_direction="left" hide_on_mobile="no" center_content="no" min_height="none"][1].Over time as a result of the wide spread use of PSA screening for prostate cancer the predictive value of PNI for EPE has decreased because of a downward stage migration of prostate cancer diagnosis. Patients now elect to have definitive therapy with earlier, smaller tumors so the significance of PNI on prostate needle biopsy specimens has decreased. The presence of PNI on biopsy specimens does not preclude cure after definitive therapy, if anything without evidence of actual EPE aggressive primary therapy should be encouraged. It becomes more and more important to gain an accurate prediction of the risk category of each man in order to avoid either over or under-treatment. There still are no adequate instruments to predict EPE so we will remain blind in making proper treatment decisions for men diagnosed with prostate cancer that shows PNI.References:
1. F, Maxine S, Schmitges J, Thuret R, Bianchi M, Shariat SF, Briganti A, Jeidres C, Perrotte P, Montorsi F, Karakiewicz P. Survival benefit of radical prostatectomy in patients with localized prostate cancer: estimations of the number needed to treat according to tumor and patient characteristics. J Urol. 2012 Jul;188(1):73-83.

Gabriele Cozzi, MD, Università degli Studi di Milano. Clinica Urologica I. Fondazione IRCCS Ca’ Granda – Ospedale
Maggiore Policlinico, Milan, Italy.

Joel T. Nowak, M.A., M.S.W.[/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]