A prospective multicenter validation of RETREAT for posttransplantation HCC recurrence prediction

Background and Aims: The RETREAT(Risk Estimation of Tumor REcurrence After Transplant) score is a simple risk stratification tool for postliver transplantation (LT) HCC recurrence that has been validated in retrospective cohort studies. A prospective, multicenter study is needed to further demonstrate accuracy especially given the evolving clinical demographics and HCC transplant practice. Our aim is to validate and compare the RETREAT score to other post-LT HCC recurrence risk scores in a contemporary, prospective cohort of patients. Approach and Results: We prospectively enrolled patients with HCC who underwent LT from 8 centers between 2018 and 2022. The primary outcome was post-LT recurrence-free survival. Secondary outcomes included post-LT and post-recurrence survival. Model performance, determined using the concordance index, Akaike information criterion, integrated Brier score, and calibration, was compared to that of other established risk scores. We included 1166 patients with HCC who underwent LT, of which 78 (6.7%) had post-LT HCC recurrence after a median follow-up time of 2.2 years (IQR 1.2–3.2). The median RETREAT score was 4 (IQR 3–5) in patients with post-LT HCC recurrence and 1 (IQR 1 – 2) in patients without. Those with a RETREAT score of 0, 3, and 5+ had a 99.4%, 84.1%, and 55.6% recurrence-free survival, respectively, at 3 years post-LT. The RETREAT score was also able to stratify post-LT overall and postrecurrence survival. The RETREAT score’s concordance index was 0.81 (95% CI: 0.77–0.85) and outperformed the MORAL and RELAPSE scores across multiple metrics. Conclusions: The RETREAT score retains high accuracy for predicting post-LT HCC recurrence, further supporting RETREAT-guided post-LT HCC surveillance and care.