Multicenter prospective study of stereotactic body radiotherapy for previously untreated solitary primary hepatocellular carcinoma: The STRSPH study.

AIM To prospectively evaluate the efficacy and safety of stereotactic body radiotherapy (SBRT) for patients with previously untreated solitary primary hepatocellular carcinoma (HCC). METHODS The main eligibility criteria included the following: (1) primary solitary HCC; (2) no prior treatment for HCC; (3) Child-Turcotte-Pugh score of seven or less; and (4) unsuitability for or refusal of surgery and RFA. The prescribed dose of SBRT was 40 Gy in five fractions. The primary endpoint was three-year overall survival (OS); the secondary endpoints included local progression-free survival (LPFS), local control (LC), and adverse events. The accrual target was 60 patients, expecting a three-year OS of 70% with a 50% threshold. RESULTS Between 2014 and 2018, 36 patients were enrolled; enrolment was closed early because of slow accrual. The median tumor size was 2.3 cm. The median follow-up at the time of evaluation was 20.8 months. The three-year OS was 78% (95% confidence interval [CI]: 53-90%). The three-year LPFS and LC proportion were 73% (95% CI: 48-87%) and 90% (95% CI: 65-97%), respectively. Grade 3 or higher SBRT-related toxicities were observed in four patients (11%), and grade 5 toxicities were not observed. CONCLUSIONS This study showed acceptably low incidence of SBRT-related toxicities. LC and OS after SBRT were comparable for previously untreated solitary HCC for patients unfit for resection and RFA. Although a definitive conclusion cannot be drawn by this study, the promising results indicate that SBRT may be an alternative option in the management of early HCC.