Lymphovascular and neural invasion in low-lying rectal carcinoma

We have previously demonstrated that lymphovascular infiltration was correl ated with an increased risk for developing lymph node metastasis in rectal adenocarcinomas confined within the submucosal layer. In another study, lym phovascular infiltration was also correlated with poor prognosis for patien ts with advanced rectal cancers. Considerations that low rectal tumors have an increased risk to develop recurrence and neural invasion have been rece ntly implicated with a more localized pattern of tumor spread. We therefore assessed the lymphovascular and neural invasion in 65 specimens from patie nts with low rectal cancers who underwent curative operation to determine i ts implications in the treatment and prognosis. Lymphovascular invasion was noted in 60%, and neural invasion was found in 27% of the cases. Five-year survival rates (Kaplan-Meier method) were significantly decreased in patie nts with lymphovascular invasion (31 vs. 67%; p < 0.01) of neural invasion (30 vs. 58%; p < 0.01). Neither lymphovascular nor neural invasion was note d in Dukes' stage A tumors. There was no recurrence or distant metastasis i n these patients. However, lymphovascular and neural invasion increased wit h tumor stage. Local recurrence and distant metastasis occurred respectivel y in three and four, and five and five patients with Dukes' B and C tumors, respectively. Both Dukes' B and C cases with local recurrence had a higher incidence of neural invasion as compared with the disease-free group. Thes e results suggest that postoperative assessment of venous and neural invasi on may provide valuable information to better determine which patients with low rectal cancers would benefit from adjuvant treatment.