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