Perineural Invasion Is Associated with Poor Survival after Preoperative Chemoradiation Therapy for Advanced Lower Rectal Cancer.

BACKGROUND: Preoperative chemoradiation therapy (pCRT) is a standard procedure for patients with advanced lower rectal cancer. It has been reported that pCRT cannot prolong the survival of patients with advanced lower rectal cancer. The aim of this study is to address the controllable and uncontrollable pathological factors of pCRT in predicting local and distant recurrences.

METHODS: One hundred two patients with stages 2 and 3 cancer were consecutively enrolled to the study. The first 51 patients (October 2008-August 2010) underwent curative resection without pCRT. The latter 51 patients (September 2010-May 2015) underwent curative resection after pCRT. Pathological factors of patients were evaluated to assess the association between local and distant recurrences.

RESULTS: Multivariate analyses for local and distant recurrences of patients without pCRT revealed that the independent risk factors were tumor deposit and perineural invasion respectively. pCRT was able to diminish circumferential resection margin, tumor deposit, venous invasion, and lymphatic permeation but not neural invasion and lymph node involvement. Kaplan-Meier curve of local and distant recurrence-free survival of patients with pCRT illustrated that tumor deposit is controllable, whereas perineural invasion is uncontrollable by pCRT.

CONCLUSION: pCRT-uncontrollable perineural invasion may be a factor for distant recurrence of advanced rectal cancer patients, leading to poor survival.