Experiences of stereotactic radiation therapy for body tumor using CK (Accuray, Sunnyvale, CA) still are not so common in the world. The Korea Institute of Radiological and Medical Sciences (KIRMAS) had CK experiences for 1412 cases including 1018 body cases from June 2002 to September 2006.
There are still many issues to be solved in field of stereotactic radiation therapy for body tumor. The first of all, we do not have enough experience to decide of optimal fraction size and fraction number according to the pathology and site of tumor. We used total 36 Gy to 51 Gy in 3 fractions for body tumor. It can be varied according to the site of tumor, size of tumor, histopathologic type, and previous conventional radiation therapy. However, because we do not have clinical data enough for optimal radiation dose and fraction number, it would be important to give maximum dose to tumor on basis of tolerability of normal tissue. Secondly, movement of tumor must be considered in stereotactic body radiation therapy. Almost tumors except brain, head and neck tumor tend to move during radiation therapy, especially, in liver and lung tumor.  So, Synchronization of the linear accelerator movement with tumor displacement is accomplished by the recently introduced Synchrony system though it may not provide perfect compensation of tumor motion.
 Our experiences showed lymph node metastasis from cervical cancer and rectal cancer had outstanding results. Lymph nodes have well defined margin on computed tomography and the range of tumor motion is not so much. The overall survival rates for lung, liver, pancreas and prostate cancer were also better than the historical results, even though those were not prospective randomized study.
  In conclusion, CK is more precise treatment than conventional treatment in aspect of physical accuracy as well as novel radiation therapy, in terms of using hypofraction.  It is likely that the role of stereotactic body radiation therapy in the management of cancer will increase in the future. Accumulated experiences and well controlled prospective study would be necessary to achieve better local control and survival.
key words : CyberKnife, stereotactic radiation therapy