12 Gy gamma knife radiosurgical volume is a predictor for radiation necrosis in non-AVM intracranial tumors.
OBJECTIVE
To determine whether the 12-Gy radiosurgical volume (12-GyV) correlates with the development of postradiosurgical imaging changes suggestive of radiation necrosis in patients treated for non-arteriovenous malformation (non-AVM) intracranial tumors with gamma knife stereotactic radiosurgery (GKSRS).


METHODS
A retrospective single-institution review of 129 patients with 198 separate non-AVM tumors was performed. Patients were followed with magnetic resonance imaging (MRI) and physical examinations at 3- to 6-month intervals. Patients who developed postradiosurgical MRI changes suggestive of radiation necrosis were labeled as having either symptomatic radiation necrosis (S-NEC) if they experienced any decline in neurologic examination associated with the imaging changes, or asymptomatic radiation necrosis (A-NEC) if they had a stable or improving neurologic examination.


RESULTS
12-GyV correlated with risk of S-NEC, which was 23% (for 12-GyV of 0-5 cc), 20% (5-10 cc), 54% (10-15 cc), and 57% (>15 cc). The risk of A-NEC did not significantly change with 12-GyV. Logistic regression analyses showed that the following factors were associated with the development of S-NEC: 12-GyV (p<0.01), occipital and temporal lesions (p<0.01), previous whole-brain radiotherapy (p=0.03), and male sex (p=0.03). Radiosurgical plan conformality did not correlate with the development of S-NEC.


CONCLUSIONS
The risk of S-NEC, but not A-NEC after GKSRS for non-AVM tumors correlates with 12-GyV, and increases significantly for 12-GyV>0 cc.
Korytko
Timothy
T
Department of Radiation Oncology, University Hospitals of Cleveland and Case Western Reserve University, Cleveland, OH 44106, USA.
Radivoyevitch
Tomas
T
Colussi
Valdir
V
Wessels
Barry W
BW
Pillai
Kunjan
K
Maciunas
Robert J
RJ
Einstein
Douglas B
DB
D001921:Brain / Q000473:pathology* / Q000528:radiation effects; D001932:Brain Neoplasms / Q000601:surgery*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D011832:Radiation Injuries / Q000150:complications*; D016634:Radiosurgery / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies