Stereotactic radiosurgery for brain metastases: analysis of outcome and risk of brain radionecrosis

Abstract

Purposeto investigate the factors affecting survival and toxicity in patients treated with stereotactic radiosurgery (SRS), with special attention to volumes of brain receiving a specific dose (V10 - V16 Gy) as predictors for brain radionecrosis.Patients and MethodsTwo hundred six consecutive patients with 310 cerebral metastases less than 3.5 cm were treated with SRS as primary treatment and followed prospectively at University of Rome La Sapienza Sant'Andrea Hospital. Overall survival, brain control, and local control were estimated using the Kaplan-Meier method calculated from the time of SRS. Univariate and multivariate analysis using a Cox proportional hazards regression model were performed to determine the predictive value of prognostic factors for treatment outcome and SRS-related complications.ResultsMedian overall survival and brain control were 14.1 months and 10 months, respectively. The 1-year and 2-year survival rates were 58% and 24%, and respective brain control were 43% and 22%. Sixteen patients recurred locally after SRS, with 1-year and 2-year local control rates of 92% and 84%, respectively. On multivariate analysis, stable extracranial disease and KPS >70 were associated with the most significant survival benefit. Neurological complications were recorded in 27 (13%) patients. Severe neurological complications (RTOG Grade 3 and 4) occurred in 5.8% of patients. Brain radionecrosis occurred in 24% of treated lesions, being symptomatic in 10% and asymptomatic in 14%. On multivariate analysis, V10 through V16 Gy were independent risk factors for radionecrosis, with V10 Gy and V12 Gy being the most predictive (p = 0.0001). For V10 Gy >12.6 cm3 and V12 Gy >10.9 cm3 the risk of radionecrosis was 47%.ConclusionsSRS alone represents a feasible option as initial treatment for patients with brain metastases, however a significant subset of patients may develop neurological complications. Lesions with V12 Gy >8.5 cm3 carries a risk of radionecrosis >10% and should be considered for hypofractionated stereotactic radiotherapy especially when located in/near eloquent areas.

Institutional experience with SRS VMAT planning for multiple cranial metastases

“…This is higher than for the iPlan plans that have been our clinical standard prior to introducing the VMAT technique but since Gamma Knife plans typically use a PTV D max >140% we accepted this higher inhomogeneity to reduce the GI. The risk of radiation necrosis following cranial SRS has been reported in several studies 13, 14, 15, 16, 17, 18. More data are needed to determine if the difference in dose distribution between the planning techniques have potential clinical consequences.…”

Hippocampal-sparing and target volume coverage in treating 3 to 10 brain metastases: A comparison of Gamma Knife, single-isocenter VMAT, CyberKnife, and TomoTherapy stereotactic radiosurgery

“…9 The CI was calculated for each metastasis in the Gamma Knife and CyberKnife planning systems; however, the CI could only be calculated for the sum of the metastases in the VMAT and TomoTherapy planning systems. The total volume of brain receiving 16,12,8, and 4 Gy was also calculated.…”

Management Approach for Recurrent Brain Metastases Following Upfront Radiosurgery May Affect Risk of Subsequent Radiation Necrosis

“…33 In the setting of SRS without WBRT, the volumes of CNS tissue that receives 10 and 12 Gy have been consistently shown to correlate with risk of RN. 23,28,34 In addition to 10-and 12-Gy volumes, Sneed et al identified capecitabine/fluorouracil use within 1 Advances in Radiation Oncology: OctobereDecember 2016 Recurrent brain metastasis management after SRS affects risk of radiation necrosis month and prior SRS to the same lesion as other independent predictors of ARE after SRS. For locally recurrent metastases treated with repeat SRS, the risk of symptomatic ARE was approximately 20% at 1 year.…”