Performance of RETREAT Score in a Liver Transplant Program That Follows Total Tumor Volume Criteria

Liver transplantation (LT) is a treatment for hepatocellular carcinoma (HCC), but selecting candidates for LT is challenging. Total Tumor Volume (TTV) criteria for selecting LT patients is broader compared to the more widely used Milan criteria. The Risk Estimation of Tumor Recurrence After Transplant (RETREAT) score was developed in Milan-based programs to predict post-LT recurrence risk, but its performance in TTV-based LT programs remains unclear. This study evaluates the RETREAT score's ability for predicting recurrence in a TTV-based LT program.

A retrospective cohort study of 302 LT recipients with HCC was conducted at the University of Alberta. Patient demographics, tumor characteristics, AFP levels, microvascular invasion, and recurrence outcomes were analyzed. RETREAT score was calculated using tumor size, number of tumors at explant, AFP levels, and microvascular invasion. Statistical analyses included Kaplan-Meier survival estimates and discrimination testing using the C-statistic.

302 patients were included, with a median follow-up of 6.3 years. 37 patients (12.2%) developed HCC recurrence. The recurrence rate at 1, 2, 3, and 5 years was 1.6%, 6%, 8%, and 13%, respectively. Recurrence rates according to RETREAT scores were 1% (score 0), 4% (score 1), 19% (score 2), 12% (score 3), 28% (score 4), 67% (score 5), 28% (score 6), and 100% (score 7). The C-statistic for recurrence prediction was 0.786 for RETREAT, 0.660 for Milan criteria in the explant, and 0.719 for TTV in the explant.

The RETREAT score is an effective tool for predicting recurrence risk in a TTV-based LT program, making it useful for identifying high-risk patients.