UNOS Down-Staging Criteria for Liver Transplantation of Hepatocellular Carcinoma: Systematic Review and Meta-Analysis of 25 Studies.

BACKGROUND & AIMS: Down-staging is commonly used to select patients with hepatocellular carcinoma (HCC) beyond Milan criteria (MC) for liver transplantation (LT), but outcomes are heterogenous. We aimed to estimate pooled down-staging success rates, HCC recurrence, and overall survival (OS), stratified by criteria used for baseline tumor burden. METHODS: We searched Pubmed and EMBASE databases from inception until August 2021 for studies reporting down-staging success (reduction of tumor burden to within MC) and outcomes of adult HCC patients. In addition, we performed a pooled analysis using reconstructed individual participant data to obtain robust estimates for OS. RESULTS: We screened 1059 articles and included 25 articles involving 3997 patients. Overall, 55.16% (45.49%-64.46%) underwent successful down-staging, and 31.52% (24.03%-40.11%) received LT (by intention-to-treat analysis [ITT]). Among patients who received LT, 16.01% (11.80%-21.37%) developed HCC recurrence. Comparing studies that used the United Network for Organ Sharing Down-Staging (UNOS-DS) criteria versus studies beyond UNOS-DS or did not specify criteria, down-staging success (by ITT) was 83.21% versus 45.93%, P < .001; the proportion who received LT (by ITT) was 48.61% vs 28.60%, P = .030; and HCC recurrence (among patients who received LT) occurred in 9.06% versus 20.42%, P < .001. Among studies that used UNOS-DS criteria, ITT 1- and 5-year OS from the initiation of down-staging treatment was 86% and 58%, respectively, whereas 1- and 5-year post-LT OS was 94% and 74%, respectively. CONCLUSIONS: Among studies that adhered to UNOS-DS criteria, down-staging was successful in four-fifths of patients, >50% received LT, and post-LT outcomes were excellent. These data provide clinical validation for the utilization of UNOS-DS criteria.