Perineural invasion is always present in the final prostatectomy specimen, if the pathologist looks carefully. Basically, the prostate cancer cells are attracted to nerve fibers inside the prostate gland that regulate the amount of prostate fluid secreted. On the other hand, if perineural invasion is seen on a prostate needle biopsy specimen, it is associated with a higher risk that the cancer has spread at least microscopically outside the prostate capsule, but this is not always the case. In the final prostatectomy specimen, it has little predictive significance.