Clinical features, treatment patterns, and outcomes of young-onset hepatocellular carcinoma: a tertiary cohort analysis with a nationwide population-based study.
Background/Aims Hepatocellular carcinoma (HCC) in younger patients is uncommon, and its clinical behavior and prognosis remain unclear. We aimed to evaluate the characteristics, treatment patterns, and outcomes of young-onset HCC using large-scale datasets. Methods This study analyzed two cohorts: the Asan Medical Center (AMC) HCC registry (2009-2023) and the nationwide Korean Liver Cancer Association (KLCA) registry. Young-onset HCC was defined as age ≤40 years. The primary comparison was between young (≤40 years) and non-young (>40 years) patients, with additional analyses using three age groups (≤40, 41-65, >65 years). Propensity score matching (PSM) was used to adjust for baseline differences. Overall survival (OS), recurrence-free survival (RFS), treatment patterns, and treatment intensity were evaluated. In the KLCA cohort, survival analyses were restricted to patients diagnosed between 2015 and 2021. Results A total of 21,699 AMC patients and 21,172 KLCA patients were included. Young-onset HCC accounted for 955 (4.4%) and 627 (3.0%) of cases, respectively. Before matching, younger patients had larger tumors, higher alpha-fetoprotein levels, and more advanced disease. After PSM, OS was comparable between groups in the AMC cohort (median 3.8 vs. 4.0 years; p=0.890) and in the KLCA cohort (median 3.7 vs. 2.9 years; p=0.053). Stage-stratified analyses showed no significant differences in OS. RFS was also similar between groups in the AMC cohort. Initial treatment distribution and longitudinal treatment intensity were comparable between groups, whereas patients aged >65 years were less likely to receive curative treatments. Conclusions Young-onset HCC shows more aggressive tumor features but similar outcomes after adjustment. Age alone may not be an independent determinant of prognosis.