Clinical Observation on Cyberknife Radiosurgery Treatment for Unresectable Primary Intrahepatic Cholangiocarcinoma

Objective To report the outcomes of Cyberknife stereotactic body radiotherapy(SBRT) for patients with unresectable primary intrahepatic cholangiocarcinoma(ICC). Methods Twenty-eight patients with ICC were treated with Cyberknife SBRT. The median prescription dose was 45Gy(range, 36-54Gy). The prescribed radiation dosage was fractionated 3 to 5 times with a 70% to 92% isodose line. Treatment response was graded by RECIST v.1.1. The survival rate and disease control rate were compared by Kaplan- Meier analysis and toxicity was evaluated according to the Radiation Therapy Oncology Group(RTOG) Toxicity Criteria, Version 2.0. Patient records were reviewed and compared using multivariate analysis(Cox regression) to determine the factors that affected survival time of ICC patients. Results The median follow-up time was 16months (3-42 months). After SBRT, evaluated by CT or MRI, 3(10.7%) patients had complete response(CR), 10(35.7%) patients showed partial response(PR), 12(42.9%) patients were stable disease(SD), 3(10.7%) patients were progressive disease(PD). The local control rate(CR+PR) was 42.9% and disease control rate(CR+PR+SD) was 89.3%. Median survival time was 15 months (95%CI: 7.22-22.78). 1- and 2-year overall survival were 57.1% and 32.1%, respectively. Multivariate analysis revealed that larger tumor size, synchronous lymph node metastases and later clinical stage were associated with poorer prognosis(P<0.01). Toxicity mainly consisted of grade 1-2. No toxicity greater than grade 3 was observed. Conclusion Cyberknife SBRT is safe and effective for unresectable primary ICC with acceptable toxicity.