Outcomes After Stereotactic Body Radiation Therapy (SBRT) as a Bridging Modality to Liver Transplantation (LT) for Hepatocellular Carcinoma (HCC)

Abstract: Purpose /Objectives: For patients with HCC awaiting LT, SBRT has emerged as a bridging treatment to ensure patients maintain priority status and eligibility per Milan criteria. In this study, we aimed to determine the efficacy and safety of SBRT in such situations. Methods A retrospective analysis was conducted of the outcomes of 27 patients treated with SBRT who were listed for LT at one institution. Among these, 20 patients and 26 tumors went on to LT and were the focus of this study. Operative reports and postoperative charts were evaluated for potential radiation related complications. The explant pathology findings were correlated with equivalent dose in 2 Gy fractions (EQD2) and tumor size. Results Median pretreatment tumor size was 3.05 cm. Median total dose of radiation was 50 Gy delivered in 5 fractions. Pathologic complete response (pCR) was achieved in 16 tumors (62%.) Median interval from end of SBRT to transplant was 287 days. Of the 21 tumors imaged prior to transplant, 16 or 76% demonstrated a clinical complete response (cCR) based on mRECIST criteria. There was no significant correlation between pCR rate and increasing tumor size (OR, 0.95; 95% CI, 0.595-1.53) or pCR rate and EQD2 (OR, 1.03; 95% CI, 0.984-1.07.) No patients experienced radiation related operative or postoperative complications. Of the 27 patients who were listed for transplant, the dropout rate was 22%. Two of the five patients with Child-Pugh score 10 died of liver failure. Conclusions This data demonstrates that SBRT as a bridging modality is a feasible option with a pCR rate comparable to that of other bridging modalities and no additional radiation related operative or postoperative complications. There was no dose dependence nor size dependence for pCR rate, which may indicate that for the tumor sizes in this study, the radiation doses delivered were sufficiently high.