Histopathologic Response and Oncologic Outcomes After Segmental and Subsegmental Transarterial Chemoembolization and Radioembolization for Hepatocellular Carcinoma.

Background: Patients with hepatocellular carcinoma (HCC) are bridged or downstaged to transplant with locoregional therapies (LRT) including transarterial chemoembolization and radioembolization (TARE). Our aim was to compare histopathologic outcomes of TACE and TARE and determine predictors of complete pathologic necrosis (CPN).

Methods: HCC treated with segmental (two segments or less) or subsegmental TACE or TARE and transplanted between January 2014 and March 2022 at a single center were retrospectively reviewed. Histopathologic and post-transplant outcomes were assessed within two years. Multivariable logistic regression, propensity score matching (PSM), and Kaplan-Meier survival analysis were performed.

Results: 208 tumors in 148 patients were treated with segmental or subsegmental TACE or TARE. In total, 132 (63.5%) tumors achieved CPN and 156 (75%) had >90% necrosis on explant. CPN by tumor in the TACE and TARE cohorts was 29% and 83.3%, respectively (p<0.0001). Target tumor complete radiologic response (mRECIST) after TARE had a higher positive predictive value (PPV) (89%) compared to TACE (42.9%). PSM analysis of TACE and TARE demonstrated independent predictors of CPN were time from last treatment to transplant, subsegmental injection, and TARE. Patients who achieved overall CPN had significantly longer recurrence free survival at two years (p=0.02).

Conclusions: In a cohort of patients who were bridged or downstaged to LT, there was improved recurrence-free survival in those who achieved complete pathologic necrosis. Overall, TARE was superior to TACE in achieving pathologic necrosis.