Clinical Outcomes of Patients Receiving Stereotactic Body Radiotherapy Dose De-escalation for Hepatocellular Carcinoma at the Hepatic Hilum

Stereotactic body radiation therapy (SBRT) for centrally located hepatocellular carcinomas (HCCs) can cause severe central biliary toxicity. However, dose de-escalation SBRT has the potential to reduce biliary toxicity with excellent tumor control. Therefore, we aimed to retrospectively evaluate the efficacy and toxicity of de-escalated SBRT in patients with hepatic hilum HCC. Patients diagnosed with peripherally located HCC received SBRT (40 Gy in five fractions), and those with centrally located HCC received de-escalated SBRT (35 Gy in five fractions) between January 2016 and August 2023 in National Cancer Center Hospital East. Of the total 42 consecutive patients evaluated, 16 (38%) were diagnosed with centrally located HCC. The median observation time was 25 months (interquartile range=10-43). The 2-year cumulative incidences of local recurrence were 17.3% and 8.1% in patients with centrally and peripherally located HCC, respectively. No statistically significant differences were observed in the cumulative incidence of local recurrence, OS, or PFS between patients with centrally and peripherally located HCC. Univariate analysis of OS showed that a smaller clinical target volume of <20 ml was significantly associated with a better OS compared to a larger volume (p=0.017). No patient experienced grade 3 or higher treatment-related adverse events. Dose de-escalation SBRT for centrally located HCC showed good local control with no grade 3 or more RT related toxicities, suggesting it may be a safe alternative.