Radiosurgery of benign intracranial meningiomas: factors associated with successful treatmentKeywords: meningioma, outcome, gamma knife, radiosurgery, skull baseInteractive ManuscriptAsk Questions of this Manuscript: What is the background behind your study?Radiosurgery of benign intracranial meningiomas is an accepted management option. What is the purpose of your study?Proper patient selection is essential to ensure good patient outcomes. Describe your patient group.The majority of tumors (n=337, 81%) involved the skull base/tentorium. The mean tumor volume was 9.2 cm3 (range, 0.3-48.6); the mean tumor margin dose was 15.9Gy (range, 12-20). The mean follow-up was 74 months (range, 6-234). Describe what you did.Restrospective analysis of the prospectively acquired Mayo Gamma Knife data base of 417 patients (305 women/112 men) having single-fraction SRS for imaging defined (n=251) or confirmed WHO Grade I (n=166) meningiomas from 1990-2008, using the Leksell Gamma Unit. Excluded were patients with radiation-induced tumors, meningiomatosis, or Neurofibromatosis. Describe your main findings.Tumor growth of the irradiated tumor was noted in 11 patients (2.6%) and adjacent to the irradiated tumor (marginal failure) in 13 patients (3.1%). The 5-year and 10-year actuarial local control (LC) rate was 96% and 89%, respectively. Prior tumor resection was associated with a higher treatment failure rate (HR=8.3, 95% CI 2.5-27.8, P<0.001). The 1-year and 5-year actuarial complication rate was 6% and 11%, respectively. Increasing tumor volume (HR=1.06, 95% CI 1.03-1.09, P<0.001) and tumors of the falx/convexity (HR=3.0, 95% CI 1.6-5.6, P=0.004) were associated with permanent treatment-related complications. A grading system was tested based on three factors tumor location (skull base/tentorium=0, falx/convexity=1) + prior resection (no=0, yes=1) + tumor volume (<4.0 cm3=1, 4.0-10.0 cm3=2, >10.0 cm3=3), yielding a score from 1-5. The percentage of patients with LC without treatment-related complications correlated with the calculated meningioma score: 1 point (n=70, 94%), 2 points (n=120, 92%), 3 points (n=116, 85%), 4 points (n=94, 76%), 5 points (n=17, 35%). Describe the main limitation of this study.This was a retrospective study. Describe your main conclusion.Single-fraction SRS at the studied dose range provided a high rate of tumor control for patients with benign intracranial meningiomas. Describe the importance of your findings and how they can be used by others.Patients with small volume, un-operated skull base or tentorial meningiomas had the best outcomes after single-fraction SRS. Radiosurgery of benign intracranial meningiomas is an accepted management option. Proper patient selection is essential to ensure good patient outcomes. The majority of tumors (n=337, 81%) involved the skull base/tentorium. The mean tumor volume was 9.2 cm3 (range, 0.3-48.6); the mean tumor margin dose was 15.9Gy (range, 12-20). The mean follow-up was 74 months (range, 6-234). Restrospective analysis of the prospectively acquired Mayo Gamma Knife data base of 417 patients (305 women/112 men) having single-fraction SRS for imaging defined (n=251) or confirmed WHO Grade I (n=166) meningiomas from 1990-2008, using the Leksell Gamma Unit. Excluded were patients with radiation-induced tumors, meningiomatosis, or Neurofibromatosis. Tumor growth of the irradiated tumor was noted in 11 patients (2.6%) and adjacent to the irradiated tumor (marginal failure) in 13 patients (3.1%). The 5-year and 10-year actuarial local control (LC) rate was 96% and 89%, respectively. Prior tumor resection was associated with a higher treatment failure rate (HR=8.3, 95% CI 2.5-27.8, P<0.001). The 1-year and 5-year actuarial complication rate was 6% and 11%, respectively. Increasing tumor volume (HR=1.06, 95% CI 1.03-1.09, P<0.001) and tumors of the falx/convexity (HR=3.0, 95% CI 1.6-5.6, P=0.004) were associated with permanent treatment-related complications. A grading system was tested based on three factors tumor location (skull base/tentorium=0, falx/convexity=1) + prior resection (no=0, yes=1) + tumor volume (<4.0 cm3=1, 4.0-10.0 cm3=2, >10.0 cm3=3), yielding a score from 1-5. The percentage of patients with LC without treatment-related complications correlated with the calculated meningioma score: 1 point (n=70, 94%), 2 points (n=120, 92%), 3 points (n=116, 85%), 4 points (n=94, 76%), 5 points (n=17, 35%). This was a retrospective study. Single-fraction SRS at the studied dose range provided a high rate of tumor control for patients with benign intracranial meningiomas. Patients with small volume, un-operated skull base or tentorial meningiomas had the best outcomes after single-fraction SRS. Project Roles:
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