Efficacy and safety of stereotactic body radiotherapy for hepatocellular carcinoma with tumor thrombus in right atrium: a two-center retrospective review

We sought to evaluate the efficacy and toxicity of stereotactic body radiotherapy (SBRT) for hepatocellular carcinoma with tumor thrombus in right atrium (RATT). HCC patients with RATT treated with SBRT at two institutions between June 2017 to July 2023 were analyzed. SBRT was generated to target the RATT. The primary endpoint was local control (LC) rate and incidence of SBRT-related pulmonary embolism (PE). The second endpoint were progression-free survival (PFS) and overall survival (OS) rate. Kaplan-Meier method was used to estimate PFS and OS. Univariate and multivariate analysis were used to identify predictors of survival. Twenty-two HCC patients with RATT underwent SBRT were analyzed. The median follow-up was 7.8 months. At one-month post-SBRT, 2 (9.5%) achieved complete response (CR), 13 (61.9%) achieved partial response (PR), and 6 (28.6%) patients were stable disease (SD). At three months post-SBRT, imaging assessments were available for 12 patients, demonstrating an improved response rate, with 4 patients (33.3%) achieving CR, 6 patients (50.0%) demonstrating PR, and 2 patients (16.7%) exhibiting SD. Pulmonary embolism (PE) was observed in two cases. One patient developed PE after receiving two fractions of SBRT, while the other experienced PE eight months post-SBRT. Median PFS was 3.3 months, while median OS was 7.8 months. The 3-month, 6-month, 9-month and 12-month overall survival rate was 77.3%, 54.5%, 45.5% and 31.8%, respectively. The 3-month, 6-month, 9-month and 12-month progression-free survival rate was 50.0%, 31.8%, 27.3% and 18.2%, respectively. Multivariate analysis identified that Child-Pugh score, prior TACE and immunotherapy history before SBRT were predictors of survival. In the largest case series of SBRT for RATT to date, SBRT achieved high local control with low rates of severe toxicity, suggesting SBRT is a safe and efficient treatment option for HCC patients with RATT.