Clinical outcomes and prognostic factors of stereotactic body radiation therapy for intrahepatic cholangiocarcinoma

Stereotactic body radiation therapy (SBRT) has been an emerging non-invasive treatment modality for patients with intrahepatic cholangiocarcinoma (ICC) when surgical treatment cannot be applied. The CyberKnife® is a SBRT system that allows for real-time tracking of the tumor. The purpose of this study was to evaluate the clinical outcomes and prognostic factors for ICC patients receiving this treatment. Twenty-eight patients with ICC were enrolled in the present study. The median prescription dose was 45 Gy (range, 36-54 Gy), fractionated 3 to 5 times with a 70% to 92% isodose line. Local control, overall survival, progression-free survival and toxicity were studied. The median follow-up time was 16 months (3-42 months). Based on modified Response Evaluation and Criteria in Solid Tumors (mRECIST), response rate and disease control rate of SBRT in ICC were 46.4% (13/28) and 89.3% (25/28), respectively. Median overall survival was 15 months (95% CI, 7.22-22.78). 1- and 2-years survival rates were 57.1% and 32.1%, and 1- and 2- years Progression-free Survival rates were 50.0 % and 21.4 %. Multivariate analysis revealed that number of lesions (solitary vs. multiple nodules), CA19-9 levels (≤37 U/mL vs. 37-600/>600) and TNM stage (AJCC stage) were independent prognostic factors for ICC patients treated with SBRT. Toxicity was mostly transient and tolerable. No greater than grade 3 toxicity was observed. These results suggested that CyberKnife SBRT might be a good alternative treatment for unresectable ICC.