Completion total mesorectal excision after neoadjuvant radiochemotherapy and local excision for rectal cancer

Local excision (LE) in selected cases after neoadjuvant radiochemotherapy (RCT) for locally advanced rectal cancer in clinically complete or major responders has been recently reported as an alternative to standard radical resection. Completion total mesorectal excision (cTME) is generally performed when high-risk pathological features are found in LE surgical specimens. The aim of this study was to evaluate the incidence of residual tumour and lymph node metastases after cTME in patients previously treated by RCT + LE. The secondary aims were to quantify the rate of postoperative morbidity and mortality and to evaluate the long-term oncological outcome of this group of patients.

All patients treated from 2007 to 2020 by LE for locally advanced rectal cancer with a clinically complete or major response to RCT who had a subsequent cTME for high-risk pathological factors (ypT >1 and/or TRG >2 and/or positive margins) were included in this multicentre retrospective study. Pathological data, postoperative short-term morbidity (classified according to Clavien-Dindo) and mortality and oncological long-term outcome after cTME were recorded in a database. Statistical analysis was performed using Wizard for iOS version 1.9.31.

A total of 47 patients were included in the study. The rate of R0 resection was 95.7%, and a sphincter-saving procedure was performed in 37 patients (78.7%), with a protective stoma rate of 78.4%. In 28 cases (59.6%), it was possible to perform a minimally invasive approach. A residual tumour (pT and/or pN) on cTME specimens was found in 21 cases (44.7%). The rate of lymph node metastases was 12.8%. The overall short-term (within 30 days) postoperative morbidity was 34%, but grade >2 postoperative complications occurred in only nine patients (19.1%), with a reoperation rate of 6.4%. No short-term postoperative deaths occurred. At a median follow-up of 57 months (range: 21-174), the long-term stoma-free rate was 70.2%, and the actuarial 5-year overall survival (OS), disease-free survival (DFS) and local control (LC) were 86.7%, 88.9% and 95.7%, respectively.

When patients exhibit high-risk pathological factors after RCT + LE, cTME should be suggested due to the high risk of residual tumour or lymph node involvement (44.7%). The results after cTME in terms of the rate of R0 resection, sphincter-saving procedure, postoperative morbidity and mortality and long-term oncological outcome seem to be acceptable and do not represent a contraindication to use LE as a first-step treatment in patients with major or complete clinical response after RCT.