Stereotactic Body Radiotherapy Using CyberKnife for Metastatic Liver Tumors: A Single-center Retrospective Study

Background/Aim: Liver metastases are a major cause of cancer-related mortality and present significant therapeutic challenges. Chemotherapy is preferred for multiple metastases, while surgery or stereotactic body radiotherapy (SBRT) is used for solitary or few metastases, particularly in oligometastatic cases. This study aimed to evaluate the safety and efficacy of CyberKnife SBRT (CK-SBRT) for liver oligometastases. Patients and Methods: This retrospective study analyzed patients with one to three liver metastases treated with CK- SBRT. The prescribed dose was typically 60 Gy in four fractions to 95% of the target volume, with reductions allowed if organ-at-risk (OAR) constraints could not be met. The local control (LC) and overall survival (OS) rates were estimated using the Kaplan-Meier method, and liver dose-volume parameters were assessed. Results: A total of 39 liver lesions in 27 patients were treated. At a median follow-up of 17 months, the 1-year LC and OS rates were 90% and 80%, respectively. In patients receiving 60 Gy in four fractions, these rates were 95% and 86%. No severe liver toxicity or radiation-induced liver disease occurred. Most patients met liver dose constraints, with low liver V15 and mean liver dose values. Conclusion: CK-SBRT provides effective tumor control with minimal toxicity for liver oligometastases. Careful dose planning and adherence to OAR constraints are essential to minimize toxicity risks.