BACKGROUND: Hepatocellular carcinoma (HCC) with inferior vena cava (IVC) involvement is a rare disease with poor prognosis. This study aimed to evaluate the outcome of HCC patients receiving radiotherapy (RT) to IVC tumor thrombus. METHODS: A total of 42 consecutive HCC patients treated with RT to IVC tumor thrombus between September 2007 and October 2018 were enrolled. Overall survival (OS), the response of IVC thrombus, prognostic factors and failure pattern were assessed. RESULTS: The median follow-up time was 4.4 months. The median RT equivalent dose in 2-Gy fractions was 48.75 Gy (range, 3.25-67.10). The objective response rate of IVC thrombus was 47.6% (95% confidence interval [CI], 33.3-64.3%). The OS rate at 1 year was 30.0%, with a median OS of 6.6 months (95% CI, 3.7-9.5) from the start of RT. On multivariate analysis, Child-Pugh class, lymph node metastasis, lung metastasis and objective response of IVC thrombus were independent predictors for OS. Lung was the most common site of first progression in 14 (33.3%) patients. For 32 patients without lung metastasis before RT, use of systemic treatment concurrent with and/or after RT was associated with a significantly longer lung metastasis-free survival (5.9 vs. 1.5 months, p = 0.0033). CONCLUSIONS: RT is effective for IVC tumor thrombus of HCC with acceptable adverse effects. RT might be a treatment option incorporated into combination therapy for HCC involving IVC.
