A novel waitlist dropout score for hepatocellular carcinoma - identifying a threshold that predicts worse...

It has been suggested that patients with hepatocellular carcinoma (HCC) at high risk of wait-list dropout would have done poorly after liver transplantation (LT) because of tumour aggressiveness. To test this hypothesis, we analysed risk of wait-list dropout among patients with HCC in long-wait regions (LWRs) to create a dropout risk score, and applied this score in short (SWRs) and mid-wait regions (MWRs) to evaluate post-LT outcomes. We sought to identify a threshold in dropout risk that predicts worse post-LT outcome.

Using the United Network for Organ Sharing database, including all patients with T2 HCC receiving priority listing from 2010 to 2014, a dropout risk score was created from a developmental cohort of 2,092 patients in LWRs, and tested in a validation cohort of 1,735 patients in SWRs and 2,894 patients in MWRs.

On multivariable analysis, 1 tumour (3.1-5 cm) or 2-3 tumours, alpha-fetoprotein (AFP) >20 ng/ml, and increasing Child-Pugh and model for end-stage liver disease-sodium scores significantly predicted wait-list dropout. A dropout risk score using these 4 variables (C-statistic 0.74) was able to stratify 1-year cumulative incidence of dropout from 7.1% with a score ≤7 to 39.5% with a score >23. Patients with a dropout risk score >30 had 5-year post-LT survival of 60.1% vs. 71.8% for those with a score ≤30 (p = 0.004). There were no significant differences in post-LT survival below this threshold.

This study provided evidence that patients with HCC with the highest dropout risk have aggressive tumour biology that would also result in poor post-LT outcomes when transplanted quickly. Below this threshold risk score of ≤30, priority status for organ allocation could be stratified based on the predicted risks of wait-list dropout without significant differences in post-LT survival.

Prioritising patients with hepatocellular carcinoma for liver transplant based on risk of wait-list dropout has been considered but may lead to inferior post-transplant survival. In this study of nearly 7,000 patients, we created a threshold dropout risk score based on tumour and liver-related factors beyond which patients with hepatocellular carcinoma will likely have poor post-liver transplant outcomes (60% at 5 years). For patients below this risk score threshold, priority status could be stratified based on the predicted risk of wait-list dropout without compromising post-transplant survival.