I had perineural invasion in my post-surgical pathology report. Unfortunately, I had biochemical cancer recurrence (BCR) 8 months after my RP. I'm not sure if the BCR was due to perineural invasion, or my Gleason 8 score, or my positive margins or a combo of these and many other factors.
There are some good (medical-based) discussions (at least from my limited, lay-persons perspective) regarding aspects of prostate cancer and treatment on the Mayo Clinic prostate cancer discussion board. Perineural invasion as it relates to BCR risk has been discussed by this prostate cancer community. Try a search on this topic.
See: https://connect.mayoclinic.org/group/prostate-cancer/