Liver transplantation (LT) is curative for most patients with hepatocellular carcinoma (HCC). However, 10%-15% of patients experience HCC recurrence. Patients who are reported as within Milan criteria by imaging are frequently found to be outside the criteria on explant. This under-staging of HCC worsens post-LT outcomes. However, risk factors for under-staging have not been elucidated. Furthermore, it is not known if there is regional or center-level variation in under-staging. We conducted a retrospective analysis of adult patients transplanted for HCC in the United Network for Organ Sharing (UNOS) database between 2012 and 2016. Under-staging was determined on the basis of comparing pre-LT imaging to explant findings. Kaplan-Meier methods and Cox regression were used to evaluate the impact of under-staging on HCC recurrence and post-LT survival. Mixed effects logistic regression was used to identify risk factors for under-staging and to study regional and center-level variation in adjusted analyses. A total of 5424 patients were included in the cohort, of whom 24.9% (n = 1353) were under-staged. Post-LT HCC recurrence and death were significantly associated with under-staging (each P < 0.001). In adjusted analyses, independent predictors of under-staging included age (odds ratio [OR], 1.13 per 10 years; 95% confidence interval [CI], 1.03-1.25), male sex (OR, 1.61; 95% CI, 1.36-1.89), down-staging (OR, 4.03; 95% CI, 2.65-6.11), and pre-LT alpha-fetoprotein (P < 0.001). There was also significant variation in under-staging between UNOS regions and among transplant centers, ranging from 14.8% to 38.1%. We report novel risk factors for HCC under-staging, which worsens post-LT outcomes. Significant center-level and regional variation in under-staging highlights the need for standards that achieve greater uniformity in staging.
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