Surrogate end points for overall survival and local control in neoadjuvant rectal cancer trials: statistical evaluation based on the FFCD 9203 trial.

Abstract Background In resectable rectal cancer trials, pathological parameters are early preoperative treatment efficacy measures. Their validation as surrogate end points for long-term clinical outcomes would allow to reduce trial duration. The aim was to evaluate potential surrogates for overall survival (OS) and local control (LC) in preoperative T3/T4 rectal cancer trials. Candidate variables included ypT and ypN stages, T downstaging, tumor regression grade (TRG), and circumferential resection margin (CRM) status. Patients and methods In the Federation Francophone de Cancerologie Digestive (FFCD) 9203 trial, 742 eligible patients were randomly assigned to receive preoperative radiothe…