Introduction: Efficacy of stereotactic radiosurgery in improving median survival for the treatment of GBM has been historically mixed, with most current evidence supporting its usage as a salvage or boost therapy at the time of recurrence. The adjuvant treatment of GBM with SRS at our institution is reviewed.
Methods: Consecutive patients treated with SRS for pathologically proven GBM at LSU Health in Shreveport from February 2000 to March 2013 were identified and analyzed. Patient characteristics, treatment variables and survival were correlated.
Results: 36 patients underwent 41 adjuvant treatments for GBM. 7 underwent SRS in the immediate post-operative period, following biopsy or subtotal resection, with median overall survival of 4.5 months (range 0.4-25.6 mo). 29 patients were treated for a recurrence at a median of 273 days from initial resection, with significantly increased median overall survival of 19.4 months from diagnosis and 7.9 months from recurrence (p = 0.0063). 8 of these were initially treated with standalone external beam radiotherapy (EBRT) following resection, with the remaining 21 receiving EBRT and chemotherapy with either BCNU or temozolomide. A mean lesion volume of 11.1cc received a mean maximum dose of 27.9 Gy, with a prescribed dose ranging from 10-20 Gy at the 50% isodose line. In subset analysis, treatment volume, maximum and prescribed dose, chemotherapy choice (carmustine vs. temozolomide), time to recurrence and age at diagnosis all failed to demonstrate significant effect on median survival. Withholding of systemic chemotherapy (n=8) additionally showed no statistical effect on survival; however in those patients not undergoing EBRT (n=5), median survival fell precipitously (19.2 vs. 2.5 months p=0.0001).
Conclusions: Salvage therapy with SRS following GBM recurrence has demonstrated statistical superiority over upfront post-operative boost therapy. The previously established survival advantage of post-operative EBRT has been verified.
Patient Care: -This investigation demonstrates a survival advantage in utilizing stereotactic radiosurgery at the time of recurrence from glioblastoma.
-The conclusions drawn here support the withholding of stereotactic radiosurgery until the time of recurrence and provide neurosurgeons with data on which to offer patients guidance on prognosis.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Describe the importance of patient, tumor and treatment factors in the prediction of overall survival following a diagnosis of glioblastoma.
2) Discuss the treatment options for primary as well as recurrent glioblastoma.
3) Identify appropriate candidates for stereotactic radiosurgery based upon demographic and treatment variables.
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