The role of the induction chemotherapy followed by RCT in advanced rectal cancer assessed by MRI.

Abstract

e15133 Background: Induction chemotherapy (IC) followed by concurrent radiochemotherapy (RCT) and total mesorectal excision (TME) is a treatment option for loco-regionally advanced rectal carcinomas (T3/T4 N0 and any T with positive adenopathies). Postoperatively, depending on the findings of the histopathological examination performed on the excision sample, patients shall undertake or not adjuvant CT. Induction chemotherapy (IC) has major benefits: rapid symptomatic response, early treatment of micrometastases, high compliance of patients with the treatment, decreased acute and chronic toxicity as compared to adjuvant CT. Concurrent RCT has shown a decrease in local recurrence rate, possibility of performing sphincter-preserving surgery or even full sterilization of surgical sample. Methods: The patients enrolled in the study have undertaken 4-6 cycles of induction CT with CapeOx and concurrent preoperative RCT. All patients have been preoperatively restaged based on MRI, for the purpose of assessing the efficacy of the induction treatment, translated through the decrease of the PT dimension, the numerical and size decrease of N and the decrease of the distance between the lower pole of the PT against the anus and the correlation of MRI response to neoadjuvant therapy with the histopathological examination of the resection sample. Results: During January-September 2015, 27 patients who had received clinical and imaging diagnosis of rectum adk, stage cTNM II and III, have been included in a prospective phase 2 trial. All patients have concluded the neoadjuvant therapy. This trial has shown the efficacy of induction CT based on an objective response rate of 72.84%. The MRI reassessment following RCT has shown an objective response rate of 90.91% and negative MRF in 61.81% of the patients. R0 resection margin has been 100% until now. Out of the 27 patients, TME has been performed up to present day in 13 of the patients, obtaining a pCR in 4 of them and a partial response in 5 of them. Conclusions: The efficacyof induction chemotherapy with CapeOx followed by concurrent RCT has been proved by the substantial reduction of the primary tumour size, the numerical and size decrease of adenopathies.