Background: To determine if SBRT followed by sorafenib (SBRT/S) improves overall survival (OS), progression free survival (PFS) and quality of life (QOL) vs. sorafenib alone (S), in patients (pts) with HCC. Methods: Eligible pts had new or recurrent HCC, unsuitable for surgery, ablation or TACE, with Zubrod performance status (PS) 0-2, Child-Pugh (CP) A, BCLC stage B or C, ≤ 5 HCCs, sum of hepatic HCCs ≤ 20 cm, and distant metastases ≤ 3 cm. Pts were randomized 1:1 to S 400 mg BID vs. SBRT (27.5-50 Gy in 5 fractions) followed by S 200 mg BID, increased to 400 mg BID after 28 days. Primary endpoint was OS; reported secondary endpoints - PFS, adverse events (AEs - CTCAEv4), and QOL (improvement in FACT-Hep score by ≥ 5 points from baseline to 6 months). Planned sample size was 292 pts (238 OS events, HR=0.72, 80% power, 1-sided α=0.05). Accrual closed early, due to a change in HCC standard of care. Statistics were amended to report as of 7/1/2022, projecting 155 OS events, with 65% power and the same α. OS and PFS were estimated by Kaplan-Meier and arms compared using log-rank test. Cox proportional hazards models were used to analyze treatment effect. Secondary endpoints were tested with 2-sided α=0.05. Results: Of 193 pts accrued from April 2013 to March 2021 from 23 sites, 177 eligible pts were randomized to S (n=92) vs. SBRT/S (n=85). Median age was 66 yrs (27-84); 41% had Hep. C; 19% had Hep. B or B/C. 82% were BCLC stage C. 74% had macrovascular invasion (MVI), 63% with VP3 or VP4 MVI. 4% had metastases. Median sum of max diameter of HCCs was 8.2 cm for S and 6.7 cm for SBRT/S; 40% had a single HCC. Median follow-up for all and alive pts was 13.2 and 33.7 mo. 22% of S pts received SBRT after discontinuing S. With 153 OS events, median OS was improved from 12.3 mo. (90% CI 10.6, 14.3) with S to 15.8 mo. (90% CI 11.4-19.2) with SBRT/S (HR=0.77, 1-sided p=0.0554). After adjusting for PS, M stage, CP A5 vs. 6, and degree of MVI, OS was statistically significantly improved for SBRT/S (HR=0.72, 95% CI 0.52-0.99, 2-sided Cox p=0.042). Median PFS was improved from 5.5 mo. (95% CI 3.4-6.3) with S to 9.2 months (95% CI 7.5-11.9) with SBRT/S (HR=0.55, 95% CI 0.40-0.75, 2-sided p=0.0001). 8 grade (G) 3+ bleeds were seen: 5 in S arm (1 G3 variceal, 2 G3 upper GI, 1 G3 hepatic, and 1 G4 abdominal) and 3 post SBRT/S (2 G3 upper GI, 1 G3 lower GI). Treatment-related G3+ AEs were not significantly different (S - 42%; SBRT/S - 47%; p=0.52), with 3 G5 AEs (S - 1 hepatic failure, 1 death NOS; SBRT/S - 1 lung infection). 83 (47%) pts consented to QoL. Of 20 S and 17 SBRT/S pts with QoL assessments at baseline and 6 months, 10% on S improved in FACT-Hep score vs 35% on SBRT/S. Conclusions: Compared to S alone, SBRT improved OS & PFS in patients with HCC, with no observed increase in AEs, and a strong suggestion for QOL benefit at 6 months. Supported by U10CA180868 (NRG Onc. Op., U10CA180822 (NRG Onc. SDMC), UG1CA189867 (NCORP), and U24CA180803 (IROC) from the NCI. Clinical trial information: NCT01730937.