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MO_2_2492 - Clinical Outcomes and Safety Profile of Salvage External Beam Radiation Therapy and Re-Irradiation for Recurrent Atypical Meningioma

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Clinical Outcomes and Safety Profile of Salvage External Beam Radiation Therapy and Re-Irradiation for Recurrent Atypical Meningioma
W. C. Chen1, J. Hara2, S. Magill3, A. Wu1, M. K. Aghi3, P. V. Theodosopoulos3, A. Perry4, M. W. McDermott3, P. K. Sneed5, S. E. Braunstein5, and D. Raleigh6; 1University of California San Francisco, Department of Radiation Oncology, San Francisco, CA, 2University of Hawaii, John A. Burns School of Medicine, Honolulu, HI, 3University of California San Francisco, Department of Neurological Surgery, San Francisco, CA, 4University of California San Francisco, Department of Pathology, San Francisco, CA, 5University of California, San Francisco, San Francisco, CA, 6University of California, San Francisco, Department of Radiation Oncology, San Francisco, CA

Purpose/Objective(s): The purpose of this study was to examine long-term clinical outcomes and toxicity associated with salvage external beam radiotherapy (EBRT) and re-irradiation of recurrent atypical meningioma (AM).

Materials/Methods: A retrospective chart review was conducted of patients who underwent salvage treatment of recurrent AM between 1996 and 2017. All patients underwent surgical resection as part of primary treatment of AM. Recurrence was defined radiographically based on modified RECIST criteria as a ≥20% increase in tumor size along any dimension on surveillance MRI. Clinical and toxicity data were extracted from the medical record and analyzed using the Kaplan-Meier method.

Results: Twenty-four patients with recurrent AM underwent 25 EBRT treatments with a median imaging follow-up after EBRT of 3.5 years (interquartile [IQ] range 1.6-4.8). Fifteen patients (63%) also underwent salvage surgery, with gross-total resection of recurrent tumor in 5 patients (33%), and 4 patients (17%) underwent combined salvage radiotherapy with EBRT+fixed frame stereotactic radiosurgery [ffSRS] (13%) or EBRT+I-125 brachytherapy (4%). 7 patients (29%) had a history of prior radiotherapy (RT) for AM in the form of EBRT (8%), ffSRS (16%), and EBRT/ffSRS in 1 (4%). The most common salvage EBRT dose was 59.4Gy in 1.8Gy fractions (N=14, 56%; range 40-59.4Gy). The overall 1, 2, and 3 year local control rates (LC) were 86%, 64%, and 35%, respectively, and the 5 year disease specific survival rate (DSS) was 67%. On univariate analysis, an EBRT dose ≤54Gy (N=10) was associated with a shorter median disease free interval (1.4 years versus 2.7 years, p=0.043, Log-rank), as was male gender (N=10, 1.8 versus 3.7 years, p=0.048), while gross-total resection, age, number of prior recurrences, and prior RT were not. When restricted to first recurrence (N=18), an EBRT dose ≤54Gy still showed a trend towards shorter disease free interval (1.4 years versus median not reached, p=0.12), with 67% of patients receiving dose ≤54Gy recurring versus 30% receiving 59.4Gy. Two patients (8%) experienced RTOG grade ≥3 toxicity: radiation necrosis requiring resection in one and cerebral edema leading to functional decline and hospitalization in another. The latter occurred in a patient receiving re-irradiation, resulting in a RTOG grade ≥3 toxicity rate of 14% among patients with prior RT.

Conclusion: Clinical outcomes and toxicity rates of salvage EBRT are reported here. In this study, a dose of ≤54Gy was associated with more rapid recurrence of disease, although this result should be interpreted cautiously due to possible selection bias. The safety of higher radiation doses in the setting of salvage treatment and prior radiation needs to be determined on a patient by patient basis.

Author Disclosure: W.C. Chen: None. J. Hara: None. A. Wu: None. P.V. Theodosopoulos: None. A. Perry: None. M.W. McDermott: None. P.K. Sneed: Honoraria; CareCore National, LLC. Travel Expenses; CareCore National, LLC. Board Member; North American Gamma Knife Consortium. S.E. Braunstein: Advisory Board; Radiation Oncology Questions, LLC. D. Raleigh: None.

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