[Perineural invasion and surgical treatment of the pancreas head cancer].

It is thought that perineural invasion by pancreatic cancer takes place either by means of direct tumor invasion of the perineural space or by means of tumor invasion through the vessels perforating the perineurium. The manner of tumor progression may be divided into four types: (1) direct progression of cancer cells into the perineural space, (2) branching at the bifurcation of the nerve fascicle, (3) perineural invasion by a probing cancer tip, and (4) invasion beyond the perineurium through defects in it. Because pancreatic cancer is often followed by severe tumor invasion of surrounding organs, major blood vessels and extrapancreatic plexus, the survival rate after the conventional pancreatoduodenectomy has been unsatisfactory. Since 1977, the author has used extended pancreatectomy with a trans-lateral retroperitoneal approach, involving resection of the portal vein, extensive excision of the retroperitoneal lymph nodes and complete resection of the pancreatic head plexus. After this surgery, 11 patients survived for more than 3 years. The five-year survival rate was 25% in case where this operation was rated as being a macroscopic curative resection.