I have a different cancer than yours, but I had Perineural Invasion, PNI, found in the biopsies of several surgeries I had for recurrences in my cervical neck, and had further chemoradiation for it. The biology of PNI and prognostics are not fully understood or its impact on survival known, but is considered a negative prognostic feature, and a route which cancer can spread along the nerves.
I hope this helps, and good luck.
