Survival of patients with complete metabolic response on [ ¹⁸ F]FDG PET/CT after chemotherapy prior to transplantation for colorectal liver metastases

Background and aims: The primary aim was to compare disease-free survival (DFS), overall survival (OS), and post relapse survival (PRS) in patients undergoing transplantation for colorectal liver metastases (CRLM) who achieved complete metabolic response (CMR) on pre-transplant [ 18 F]FDG PET/CT after chemotherapy, with patients presenting with low or high metabolic tumor volume (MTV). Methods: Pre-operative [ 18 F]FDG PET/CT and diagnostic CT scans from 45 patients included in the Secondary Cancer (SECA) 1 and 2 studies were evaluated. MTV was derived from the [ 18 F]FDG PET/CT, and patients with CMR (MTV = 0) were identified. Patients were stratified into three subgroups: MTV 0, MTV low, and MTV high. DFS, OS, and PRS were compared using the Kaplan–Meier method and the log-rank test. Baseline characteristics and CT reassessment data were analyzed using the Mann–Whitney U test for continuous variables and Fisher′s exact test for categorical variables. Results: Thirteen patients with CMR had significantly longer DFS and OS than patients in the MTV high group ( p = 0.033 and 0.030), but significantly shorter DFS and OS than those in the MTV low group ( p = 0.042 and 0.018). PRS did not differ significantly between patients with CMR and those with low or high MTV ( p = 0.121 and 0.130). Imaging findings of extensive growth along the liver capsule and/or possible tumor extension beyond the liver capsule on CT had significantly shorter OS ( p = 0.010 and <0.001), including after exclusion of the MTV high group (0.034 and <0.001). Conclusion: Patients with CMR on [ 18 F]FDG PET/CT after chemotherapy prior to liver transplantation for CRLM had intermediate DFS, OS, and PRS compared with patients with low and high MTV.