Abstract
Downstaging of hepatocellular carcinoma (HCC) is typically defined as the reduction in size or number of viable tumors through locoregional therapy (LRT), aiming to meet the established criteria for liver transplantation (LT). According to the Barcelona Clinic Liver Cancer (BCLC) staging system, a subgroup of patients with BCLC-B may benefit most from downstaging therapies. The United Network Organ Sharing downstaging protocol identifies potential candidates for downstaging by setting out 'inclusion criteria' and defining 'successful downstaging.' Additionally, the protocol considers factors related to tumor biology, such as an alphafetoprotein level <500 ng/mL after LRT. Reports indicate that successful downstaging rates following LRT are about 50%, with post- LT recurrence rates comparable to those of patients within the Milan criteria. A comprehensive multicenter US study on 10-year outcomes post-LT after downstaging showed 10-year post-LT survival and recurrence rates of 52.1% and 20.6%, respectively, for patients whose disease was downstaged; this compares to 61.5% and 13.3% for those consistently within the Milan criteria. Recently, the development of effective systemic treatments for HCC, such as immuno-oncologic agents, has provided additional opportunities for downstaging. Numerous clinical trials are exploring a multidisciplinary approach (MDA) combining LRT and systemic therapy. Although concrete evidence of the superiority of MDA for HCC downstaging is lacking, some retrospective studies and phase I and II trials have shown promising results regarding the efficacy and safety of MDA for this purpose. In this review, we will also discuss the future of MDA protocols in downstaging for improved clinical outcomes.