Objective  This study aims to evaluate the clinical efficacy of Cyberknife for treating colorectal cancer(CRCa) patients with liver metastases.

  Methods  Data of 22 CRCa patients with liver metastases were retrospectively studied.All patients were admitted to Tianjin Cancer Hospital from October 2006 to May 2012.They were implanted with a gold marker in the lesions or around the tumor less than 2 cm under computer tomography or ultrasound.The total radiation dose was(39-50) Gy/(3-6) fractions according to the location of liver metastases.None received concurrent chemotherapy during Cyberknife radiotherapy.

  Results  All patients successfully completed the Cyberknife treatment.The median overall survival was 50 months(range, 15 to 55 months).The one-, two-, and three-year survival rates were 100%, 94%, and 72.5%, respectively.The median progression-free survival was 28 months(range, 2.3 to 44 months).The local control for one year or more was 82.6%.The patients that received systemic therapy before Cyberknife showed relatively good local control(P= 0.07).The most common toxicity was grade 1 or 2 nausea, vomiting, and weakness.No grade Ⅲ or worse acute toxicity was found.No late toxicity was also observed.

  Conclusion  Cyberknife is a safe and effective treatment for CRCa patients with liver metastases.