Stereotactic Body Radiotherapy as a Salvage Therapy after Incomplete Radiofrequency Ablation for Hepatocellular Carcinoma: A Retrospective Cohort Study

Residual tumor tissue after radiofrequency ablation (RFA) is inevitable in clinical practice, and the optimal management of residual tumor after RFA has not been established. To evaluate the efficiency and toxicity of stereotactic body radiotherapy (SBRT) as a salvage therapy after incomplete RFA for hepatocellular carcinoma (HCC), we retrospectively included 32 HCC patients with an initial incomplete response (iIR) to RFA from May 2011 to August 2018. An iIR was defined as the presence of residual enhancement on CT or MRI one month after RFA treatment. The primary endpoint was local tumor control (LTC); the secondary endpoints included progression-free survival (PFS), overall survival (OS), and toxicity. All patients fulfilled 6 fractions of SBRT as planned, with dosages ranging from 30 Gy to 54 Gy. The objective response rate (ORR) was 50.0%. The 1- and 2-year LTC rates were 86.6% (95% CI, 74.3% to 98.9%) and 74.7% (95% CI, 55.9% to 93.5%), respectively. Fewer times of prior treatments was associated with better LTC (HR = 11.7, P=0.026). The 1- and 2-year PFS rate were 69.9% (95% CI, 53.4% to 86.4%) and 52.7% (95% CI, 33.1% to 72.3%), respectively. A higher Child-Pugh score was the only independent risk factor for tumor progression (HR = 5.17, P=0.012). The 1- and 3-year OS rate were 85.6% and 67.1%, respectively. Only two patients suffered grade 3 adverse events, and none experienced grade 4 or 5 events. In conclusion, for HCC patients confirmed to have an iIR to prior RFA, with compensated liver function, SBRT provided favorable LTC and OS along with acceptable toxicity.