Clinical outcome of stereotactic ablative radiotherapy with CyberKnife® for lung tumors: a single center experience

Abstract

Aim: To evaluate retrospectively clinical outcomes of treated with stereotactic ablative radiotherapy (SABR) using the CyberKnife® (Accuray, Sunnyvale, CA, USA), for early primary and oligometastatic lung tumors. Methods: This descriptive study included thirty tumors from 29 patients with primary lung cancer (n=21) or oligometastatic lung tumors (n=9), who underwent SABR with robotic linear accelerator between March 2011 and July2015. Out of the 30 tumors, 21 were NSCLC, 9 were metastatic lung disease. Treatment was given using different tracking methods including fiducial tracking with Synchrony (21 patients), Xsight lung with Synchrony (4 patients) and Xsight spine (5 patients). Treatment was delivered two to three fractions per week and with different fractionations depending on location and other tumor related factors. Factors, potentially effective on local control and overall survival were investigated. Results: Median follow-up time for local control was 11 months (2.4-39 months). Of 25 patients with known follow-up data, local control (LC) rates for 1, 2 and 3 years were 82.8%, 82.8% and 55.2 %, respectively. Overall survival (OS) rates for primary lung tumor patients 1, 2 and 3 years were 72.2%, 64.2%, 51.4% and metastatic lung tumor patients for 1 year was 71%, respectively. Except for gender, none of the factors were statistically significantly associated with local control in univariate analysis; female gender was associated with worse local control (p=0.001). Also in univariate analysis of overall survival, there was a trend for worse survival in females, too (p=0.07). Conclusion: This small study may give some idea about utilizing different tracking ways for CyberKnife® with less toxicity.