Abstract: Objective To investigate the role of cyberknife in downstaging therapy before liver transplantation for patients with hepatocellular carcinoma.Methods The clinical data of 2 patients with primary liver cancer who had been treated with cyberknife during the last 2 years in our department were collected. Modified Response Evaluation Criteria in Solid Tumors Criteria was used to evaluate tumor shrinkage after downstaging treatment. Time from radiotherapy to liver transplantation and postoperative pathology diagnosis were recorded. Disease-free survival time was assessed in both patients 1 year after liver transplantation. Child-Pugh grading before and after radiotherapy was applied for evaluating the safety of radiographic knife as downstaging treatment. Results Patient 1 was in Barcelona Clinic Liver Cancer stage C (BCLC-C), who received a radiotherapy dose of 50 Gy/10f and achieved partial response (PR) after treatment. Liver transplantation was performed 3 months after radiotherapy in the patient, and no metastasis or recurrence occurred in the > 1-year follow-up. Patient 2 was in BCLC-B stage, and received a radiotherapy dose of 48 Gy/8f and achieved PR after treatment. Liver transplantation was performed 1 year after radiotherapy in the patient and no sign of metastasis or recurrence was observed in the > 1-year follow-up after transplantation. Postoperative pathology showed significant shrinkage of tumors. Liver functions of both patients before and after radiotherapy were A6 and B7, which were slightly impaired. Conclusion Cyberknife can be used as an effective downstaging treatment before liver transplantation because of its mild side effects and satisfying downstaging effects.

Key words: Hepatocellular carcinoma(HCC), Cyberknife, Stereotactic body radiotherapy, Liver transplant (LT), Downstaging therapy