Final Results of a Multicenter Prospective Study of Stereotactic Body Radiation Therapy for Previously Untreated Solitary Primary Hepatocellular Carcinoma (The STRSPH Study)

Purpose: To report final results of a prospective study of stereotactic body radiation therapy (SBRT) in patients with previously untreated solitary primary hepatocellular carcinoma (HCC). Methods and Materials: This prospective, single-arm, multicenter phase 2 trial recruited patients with HCC who were unsuitable for, or refused, surgery and radiofrequency ablation, with 3-year overall survival rates as the primary endpoint and survival outcomes and adverse events as secondary endpoints. The prescribed SBRT dose was 40 Gy in 5 fractions. The final data were analyzed in November 2022. Results: Between 2014 and 2018, 36 patients (median age, 73.5 years) were registered; enrollment was closed before full recruitment due to slow accrual. Overall, 34 patients were analyzed for efficacy evaluation after excluding 2 patients. The median tumor size was 2.3 cm. The median follow-up times for all patients and for survivors were 49 and 56 months, respectively. The 3-year overall survival rate was 82% (95% confidence interval, 65%-92%). The 3-year local control rate was 93% (95% confidence interval, 76%-98%). Grade 3 or higher SBRT-related nonlaboratory toxicities were observed in 4 patients (11%). No grade 5 adverse events were observed. Conclusions: Final results of this phase 2 trial suggest the efficacy and safety of SBRT for newly diagnosed early-stage HCC that is unfit for other local therapies. Although this study was underpowered by the small number of registrations, the excellent results indicate that SBRT may be an alternative option for the management of early-stage HCC.