Allocation policy for hepatocellular carcinoma in the MELD era: room for improvement?

Currently, liver transplantation is the optimal cure for hepatocellular cancer (HCC) limited to the liver. The requisite use of a scarce resource and the effective "competition" between transplant candidates with and without HCC necessitates an allocation policy that defines the subset of HCC patients appropriate for transplantation and their equitable waiting-list prioritization relative to non-HCC patients. Under Model for End-Stage Liver Disease (MELD) allocation, HCC candidates must meet the Milan criteria (single tumor < or =5 cm in diameter or 2 or 3 tumors, each <3 cm in diameter) to qualify for exceptional HCC waiting-list consideration. Their waiting-list prioritization is based on estimating progression risk beyond the Milan criteria (termed dropout), an event for HCC patients considered equivalent to death for non-HCC patients. Although the Milan criteria may be too restrictive, thereby denying deserving patients access to transplantation, high rates of understaging by pretransplantation radiographic imaging and concern for erosion of recurrence-free survival rates have dampened enthusiasm for relaxation of tumor guidelines. The efficacy of pretransplantation locoregional therapies to reduce dropout, downstage patients, and/or decrease posttransplantation recurrence remains to be determined. Genomic, molecular, or clinical criteria to accurately differentiate HCC patients whose disease will recur from those whose disease will not recur would resolve much of the current controversy regarding appropriate criteria for HCC patients to qualify for transplantation.