Rationale of pelvic autonomic nerve preservation in rectal cancer surgery based on immunohistochemical study.

Purpose: Previous studies revealed that the incidence of cancer cell involvement along the pelvic autonomic nerves ranged from 4 to 14%. However, patients' profiles and methodologies differed among the studies. This study was conducted to clarify the incidence of cancer cell involvement in and around the pelvic autonomic nerves immunohistochemically.

Methods: Immunohistochemical staining was performed on pelvic autonomic nerve specimens resected from 17 patients with p-Stage I-III lower rectal cancers. Antibodies used were pan-cytokeratin (AE1/AE3) for staining cancer cells, S-100 for autonomic nerves, and D2-40 for lymphatic vessels. Lymphatic permeation around the pelvic autonomic nerves was defined as present when AE1/AE3-positive cells were detected in D2-40-stained lymphatic vessels. The presence of metastasis to the interstitial tissue or contaminants was also recorded.

Results: TNM staging was stage I in 1, stage II in 5, and stage III in 11 cases, respectively. No cases had lymphatic permeation or metastasis to the interstitial tissue in and around the pelvic autonomic nerves. Cancer cell contaminants were seen in four cases (23%). In three cases (18%), metastatic nodes were located at the root of the middle rectal artery, very close to the pelvic autonomic nerves.

Conclusions: Cancer cell involvement was not seen in and around the pelvic autonomic nerves, suggesting that complete pelvic autonomic nerve preservation may be feasible, unless nerves are invaded by the tumor. In some cases, however, metastatic nodes were seen very close to the nerves. Meticulous lymph node dissection along the pelvic autonomic nerves is mandatory.