EL13 - Current status of stereotactic radiation therapy (SRT)

Abstract

Stereotactic radiotherapy (SRT) is a technique developed for intracranial tumors. On the other hand, stereotactic body radiotherapy (SBRT) is a technique introduced in the late 1990s for extracranial tumors. SBRT is a method of using single 10-20Gy of high dose and hypofractionated radiotherapy. Recently, many papers have been published on its clinical results, especially in early stage lung cancer. Therefore, to recognize the current status of SBRT in Japan, a nation-wide survey was conducted by the Japan Conformal External Beam Radiotherapy Group (J-CERG). The questionaire was sent to 227 institutions. One-hundred and forty-nine institutions responded by the end of May 2015.The purpose of this presentation is to evaluate the current status of SBRT. The key issues for SBRT are fixing apparatus, respiratory regulation, treatment planning and verification. For regulation of respiratory movement, abdominal wall compression, breath-holding, respiratory gating and tumor chasing methods were used. For irradiation technique, 6 to 10 non-coplanar beams or multiple arc beams were adopted. Daily verification before radiotherapy is mandatory for SBRT. Frequently used radiation regimens were 48 to 60 Gy in 3 to 5 fractions. The local relapse-free rates were almost always between 85 to 95% for lung cancer. Long term follow-up results have also been reported. The number of serious complications was very low. Several unanswered questions are the indication for the patients with damaged lung and the patients with central tumor. The past results of clinical trial including JCOG0403 and the currently ongoing protocols for lung cancer including JCOG1408 will be reviewed. Most updated status of SBRT will also be reviewed.