3080 - Outcomes and Predictors of Toxicity after Stereotactic Body Radiotherapy for Child-Pugh B or C Hepatocellular Carcinoma in a Fiducial-Less Setting

R. Upadhyay¹, N. Doe², Y. Gokun³, M. R. Siedow¹, A. Manne⁴, K. L. Pitter¹, A. J. Sim¹, E. D. Miller¹, and D. A. Diaz Pardo¹; ¹Department of Radiation Oncology, The Ohio State University Wexner Medical Center, Columbus, OH, ²The Ohio State University College of Medicine, Columbus, OH, ³Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University Wexner Medical Center, Columbus, OH, ⁴Department of Medical Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, OH

Purpose/Objective(s): Patients with a Child-Pugh score (CP) of B7 or higher are under-represented in otherwise robust prospective data supporting the use of stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC). We report the outcomes and toxicity after SBRT for CP =B7 HCC patients. Materials/

Methods: HCC patients with CP =B7 who received liver SBRT at our center 2015-2022 were included. Patients were treated with fiducial-less, photon based SBRT using 4D-CT with abdominal compression. The primary endpoint was overall survival (OS). Secondary endpoints were decline in CP score by =2 points at 6 months, freedom from local progression (FFLP) defined as progression of treated lesion, intrahepatic progression free survival (IH-PFS, progression outside of treated lesion), and distant PFS. Kaplan-Meier method was used for survival estimates and Cox proportional hazards models for intergroup comparisons.
Results: Thirty-one HCC patients with CP =B7 were included. Median age was 67.7 years (range 33.5 – 85.9), 29% patients were ECOG=2, 45% had macrovascular invasion (MVI), and 65%, 23%, 6% and 6% patients were CP classes B7, B8, B9 and C10, respectively. The median maximal tumor dimension was 5.3 cm (range 2.0 – 16.9), and the median gross tumor volume (GTV) was 79.9 cc (range 11.3 – 1771.6). Median radiation (RT) dose was 40 Gy (range 22.5 – 50) in 5 fractions, with 8 patients receiving a biological equivalent dose (BED) > 100 Gy, and 39% receiving systemic therapy. SBRT was well tolerated with 26% patients having any grade toxicity (most commonly nausea; 16%) and no = grade 3 toxicity. None had classic radiation-induced liver disease. The median OS and 1-year OS rate were 7.6 months and 35%, respectively. On univariate analysis, higher RT dose (Hazard ratio (HR) 0.76; 95% CI 0.60-0.96), BED>100 Gy (HR 0.20; 95% CI 0.04-0.60), higher GTV Dmean (HR 0.95; 95% CI 0.91-0.99), and lower Liver Dmean (HR 0.88; 95% CI 0.80-0.97) were associated with significantly improved OS (all p<.05). Higher Liver-GTV Dmean increased the risk of death, but the difference was not statistically significant (HR 1.14; 95% CI 1.00-1.30; p = .06). FFLP, IH-PFS, and distant PFS at 1 year were 83%, 51% and 82%, respectively. About 58% patients had any increase in CP score, with 26% increasing by =2 points. The increase in CP score was independent of tumor size, performance status, MVI, RT dose, or baseline cirrhosis. Liver-GTV Dmean was higher in patients with increase in CP =2, but not statistically significant (15.0 Gy vs 12.8 Gy, p = .06). Two patients had a liver transplant after SBRT, with a 1-year OS of 100%.
Conclusion: SBRT for CP =B7 patients is well tolerated and provides excellent local control. Higher tumor BED and lower dose to normal liver improved OS in our patient population. SBRT should be considered in the multidisciplinary treatment of advanced HCCs as well as a bridge to transplant for these patients. Enrollment in prospective clinical trials should be considered.