A Comparison of Clinical and Radiologic Outcomes Between Frame-based and Frameless Stereotactic Radiosurgery for Brain Metastases

Publication date: Available online 9 May 2016
Source:Practical Radiation Oncology
Author(s): Nathan R. Bennion, Timothy Malouff, Vivek Verma, Kyle Denniston, Abhijeet Bhirud, Weining Zhen, Andrew Wahl, Chi Lin
Purpose/Objective(s)Modern experiences in stereotactic radiosurgery (SRS) report non-invasive frameless techniques as an effective alternative to frame-based SRS. Frameless techniques potentially increase positional uncertainty and planning target volume (PTV) margins are frequently employed. Here we compare rates of local control and radiation necrosis in frameless versus frame-based SRS.Materials/MethodsNinety-eight patients (170 lesions) with radiologic and clinical follow-up were analyzed. Group 1 contained 34 patients (61 lesions) immobilized with an invasive stereotactic frame. Group 2 had 64 patients (109 lesions) immobilized with a frameless SRS mask. Patient, tumor, and treatment characteristics were recorded, as were intervals to local recurrence and radiation necrosis (asymptomatic and symptomatic).ResultsMedian patient age was 59 years (range 25–89), and KPS was 80 (range 50–100). Median radiologic and clinical follow-up was 6.5 months (range 0.7-44.3) and 7 months (range 0.7-45.7). A median of 2 tumors were treated per course (range 1–5) with a median dose of 18 Gy (range 13–24 Gy). The median time to local failure was not reached, and Kaplan-Meier estimates of local failure were not statistically significant between groups (p=0.303). Actuarial 6-month local failure rates were 7.2% in Group 1 and 12.6% in Group 2 (p=0.295), with 12-month local failure rates of 14.5% and 26.8% (p=0.185), respectively. There was no statistically significant difference in symptomatic (p=0.391) or asymptomatic (p=0.149) radiation necrosis. Six-month radiation necrosis was 0% in Group 1 and 1.6% in Group 2 (p=0.311) with 12-month rates of 20.2% and 3.8%, respectively (p=0.059). Median time to necrosis was not reached in Group 1, but was 44 months in Group 2.ConclusionFrameless SRS demonstrates clinical outcomes comparable to frame-based techniques with respect to local failure and radiation necrosis.



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