Clinical outcomes of perioptic tumors treated with hypofractionated stereotactic radiotherapy using CyberKnife® stereotactic radiosurgery.

Abstract

Stereotactic radiation technique is widely reported as an effective treatment for various types of benign intracranial tumors. However, single fraction radiosurgery (SRS) is not recommended for tumors located close to the optic apparatus due to the restricted radiation tolerance dose of the optic pathway. Recent advances in radiotherapy include advanced frameless radiosurgery using hypofractionated stereotactic radiotherapy (HSRT), and this has become an attractive treatment option for perioptic tumors within 2-3mm of the optic pathway. Accordingly, the aim of this study was to investigate the clinical outcomes of perioptic tumors treated with HSRT using CyberKnife® (CK) robotic radiosurgery system relative to tumor control, vision preservation and toxicity. This retrospective analysis of prospectively collected data included consecutive 100 patients that were diagnosed with and treated for perioptic tumor at the Radiosurgery center, Ramathibodi Hospital during the January 2009 to December 2012 study period. The median tumor volume was 6.81cm3 (range 0.37-51.6), and the median prescribed dose was 25Gy (range 20-35) in 5 fractions (range 3-5). After the median follow-up time of 37.5months (range 21-103), two patients developed tumor progression at 6 and 34months post-HSRT. The 5-year overall survival was 97%, and the 5-year local control was 97.5%. At the last follow-up, no vision deterioration or newly developed hypopituitarism was detected in our study. Although a longer follow-up is needed, HSRT yields a high level of local control and vision preservation, and should be considered a treatment of choice for perioptic tumor located close to the optic apparatus.