Abstract
BackgroundHypofractionated Radiosurgery (HR) is a therapeutic option for delivering partial brain radiotherapy (RT) to large brain metastases or resection cavities otherwise not amenable to single fraction radiosurgery (SRS). The use, safety and efficacy of HR for brain metastases is not well characterized and the optimal RT dose-fractionation schedule is undefined.MethodsForty-two patients treated with HR in 3-5 fractions for 20 (48%) intact and 22 (52%) resected brain metastases with a median maximum dimension of 3.9 cm (0.8-6.4 cm) between May 2008 and August 2011 were reviewed. Twenty-two patients (52%) had received prior radiation therapy. Local (LC), intracranial progression free survival (PFS) and overall survival (OS) are reported and analyzed for relationship to multiple RT variables through Cox-regression analysis.ResultsThe most common dose-fractionation schedules were 21 Gy in 3 fractions (67%), 24 Gy in 4 fractions (14%) and 30 Gy in 5 fractions (12%). After a median follow-up time of 15 months (range 2-41), local failure occurred in 13 patients (29%) and was a first site of failure in 6 patients (14%). Kaplan-Meier estimates of 1 year LC, intracranial PFS, and OS are: 61% (95% CI 0.53 – 0.70), 55% (95% CI 0.47 – 0.63), and 73% (95% CI 0.65 – 0.79), respectively. Local tumor control was negatively associated with PTV volume (p = 0.007) and was a significant predictor of OS (HR 0.57, 95% CI 0.33 - 0.98, p = 0.04). Symptomatic radiation necrosis occurred in 3 patients (7%).ConclusionsHR is well tolerated in both new and recurrent, previously irradiated intact or resected brain metastases. Local control is negatively associated with PTV volume and a significant predictor of overall survival, suggesting a need for dose escalation when using HR for large intracranial lesions.
Highlights
Brain metastases represent a significant cause of morbidity and mortality among cancer patients
Hypofractionated Radiosurgery (HR) may provide the benefit of improved local control and reduced neurocognitive decline when compared to whole brain radiation (WBRT), with reduced toxicity risk when compared to stereotactic radiosurgery (SRS) for large intracranial lesions or metastases in sensitive locations
Patient population Forty-seven patients treated with HR for new or progressive brain metastases or resection cavities between May 2008 and August 2011 at the Emory Clinic were identified, and 42 of these patients were included for outcomes analysis
Summary
Brain metastases represent a significant cause of morbidity and mortality among cancer patients. SRS may carry an increased toxicity risk when treating brain metastases of any size that are in close proximity to critical structures, such as the optic chiasm or brainstem, and when the location of the metastasis has previously received high radiation doses. In these instances, hypofractionated radiosurgery (HR) delivered in 3-5 fractions over multiple days is an alternative therapeutic option for delivering partial brain RT. The use, safety and efficacy of HR for brain metastases is not well characterized and the optimal RT dosefractionation schedule is undefined
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