A Simple Measure of Hepatocellular Carcinoma Burden Predicts Tumor Recurrence After Liver Transplantation: The Recurrent Hepatocellular Carcinoma–Initial, Maximum, Last Classification

Risk of recurrent hepatocellular carcinoma (rHCC) after liver transplantation (LT) depends on the pre‐LT HCC burden, tumor behavior, and response to locoregional therapy (LRT). In December 2017, LT priority for HCC was expanded to select patients outside the Milan criteria who respond to LRT. Our aims were to develop a novel objective measure of pre‐LT HCC burden (model of recurrent hepatocellular carcinoma–initial, maximum, last [RH‐IML]), incorporating tumor behavior over time, and to apply RH‐IML to model post‐LT rHCC. Using United Network for Organ Sharing data from between 2002‐2014 (development) and 2015‐2017 (validation), we identified adult LT recipients with HCC and assessed pre‐LT HCC tumor behavior and post‐LT rHCC. For each patient, HCC burden was measured at 3 points on the waiting list: initial (I), maximum (M) total tumor diameter, and last (L) exception petition. HCC burden at these 3 points were classified as (A) <Milan, (B) Milan, (C) >Milan to University of California, San Francisco (UCSF), and (D) >UCSF, resulting in each patient having a 3‐letter RH‐IML designation. Of 16,558 recipients with HCC, 1233 (7%) had any post‐LT rHCC. rHCC rates were highest in RH‐IML group CCC (15%) and DDD (18%). When M and L tumor burdens did not exceed Milan (class B or A), rHCC was low (≤10%) as in AAA, ABA, ABB, BBA, BBB; rHCC was also low (≤10%) with successful downstaging when L was A (<Milan) and M tumor burden did not exceed I, as in BBA, CCA, and DDA. In conclusion, the RH‐IML classification system is a simple summative measure of HCC burden that incorporates tumor behavior over time. RH‐IML also estimates post‐LT rHCC risk and is a useful tool for evaluating risk for rHCC post‐LT.