Induction Chemotherapy and Chemoradiotherapy Combined to ASA vs. Placebo for High-Risk Rectal Cancer: Results of a Randomized Trial

Abstract

Inductionchemotherapy (IC) followed by chemoradiation (CRT) is an attractive approach in high-risk locally advanced rectal cancer. Additionally, ASA has shown potential to improve outcomes alongside CRT in rectal cancer. The ICAR trial aimed to evaluate the safety and efficacy of IC followed by CRT with or without ASA on MRI tumor response. MethodsSingle-center, double-blind, randomized phase II trial to evaluate induction treatment with CAPOX, followed by capecitabine-based chemoradiotherapy with ASA (arm 1) or placebo (arm 2) in high-risk stage II-III rectal adenocarcinoma staged by MRI. The primary endpoint was MRI tumor regression grade (mrTRG). Secondary endpoints were pathological response, surgical outcomes, postoperative complications, treatment tolerance, DFS, and OS. ResultsBetween January 2018 and August 2019, 27 patients were eligible, 25 (92.5%) completed IC, and 23 patients were randomly assigned (12 to ASA group; 11 to placebo group). In the ASA arm, 3 pts (25%) presented distant disease progression at restaging. Seven patients (30.4%) had cCR after neoadjuvant treatment. All 13 patients submitted to surgery after neoadjuvant treatment underwent R0 resections except for 1 patient with positive CRM, and 12 patients (92.3%) had sphincter preservation. After a median follow-up of 34.9 months, the 2-year DFS was 83.1% and 3-year OS was 81.5%. ConclusionThere was good compliance in both treatment arms and encouraging cCR rate. ASA during CRT was safe but failed to improve on MRI tumor response. The study was closed due to the absence of benefits.