Panex: A pooled analysis of EXPERT and EXPERT-C, two trials of neoadjuvant chemotherapy (NACT) and chemoradiotherapy (CRT) in high-risk locally advanced rectal cancer (LARC).

3575 Background: After the use of preoperative radiotherapy and TME, survival of LARC has reached a plateau. More effective therapies, predictive/prognostic factors for treatment selection and valid endpoints for clinical trials are needed. We report the results of PANEX, a pooled analysis of EXPERT and EXPERT-C, the two largest trials of neoadjuvant CAPOX followed by CRT, TME and adjuvant CAPOX ± cetuximab in MRI-defined, high-risk, LARC. Methods: Individual patient data were collected from the central database of each trial. Survival endpoints were analysed using Kaplan-Meier methods and multivariate Cox-regression. Results: 269 patients (EXPERT=105, EXPERT-C=164) were included. Baseline features: T3c/T3d (60%), T4 (22%), CRM+ (63%), distal tumour (61%), N+ (72%), EMVI (71%). Radiologic response was 62% after NACT and 80% after CRT. Surgery was performed in 91% (R0 in 87%) and T/N downstaging was achieved in 56%/55% of cases. Pathologic complete response rate was 19%. After a median follow-up of 69 mo, ...