2025 Proffered Presentations
S184: LARGER TUMOR VOLUME ASSOCIATED WITH LOWER TUMOR SHRINKAGE FOLLOWING GAMMA KNIFE RADIOSURGERY FOR INCIDENTAL MENINGIOMAS
Tianqi Xiao, BS1; Anish Kosanam, BS1; Roger Murayi, MD2; Wei Wei, MS2; Varun R Kshettry, MD2; Pablo F Recinos, MD2; 1Case Western Reserve University School of Medicine; 2Cleveland Clinic Rose Ella Burkhardt Brain Tumor & Neuro-Oncology Center
Introduction: Meningiomas are often benign, grow indolently and discovered incidentally. The mainstay treatment is observation for small asymptomatic meningiomas and surgery for larger symptomatic meningiomas. Gamma Knife Radiosurgery (GKRS) has emerged as one of the most utilized alternatives to surgery with high reported tumor control rates. However, it is unknown how meningioma pre-treatment growth rates (PTGR) impact GKRS tumor control. Our study aimed to examine the relationship of PTGR, tumor volume, and various other factors of incidental meningiomas as predictors for tumor control after GKRS.
Methods: A retrospective cohort study was conducted of all patients >18 years of age with incidental meningiomas that underwent primary GKRS treatment at the Cleveland Clinic Foundation (CCF) between January 1st 2010 and December 31st 2020. Patients were excluded if they had multiple meningiomas, pre-GKRS surgical resection or radiation, less than 6 months of pre-GKRS volumetric MRIs, less than 2 years of post-GKRS volumetric MRIs. Patient demographics, tumor characteristics, and GKRS treatments were collected through chart review. Meningioma volumes were collected by two independent researchers using BrainLab imaging software and semi-automated segmentation. Statistical analysis was conducted by a statistician.
Results: A total of 39 patients met inclusion criteria. Patient demographics included most females (66.6%) and Caucasians (87.0%). Median age at GKRS was 65. The most common tumor location was falcine (23.1%) followed by convexity (20.5%) meningiomas. Tumor control was seen in 38/39 patients (97.4%). The one patient who had continued growth after GKRS received maximal safe resection after GKRS. The mean tumor volumes are included at the Earliest time point (2.85cm3, SD=2.11cm3), 1 year pre-GKRS (4.15cm3, SD=5.39cm3), at GKRS (5.56cm3, SD=7.28cm3), 3 months post-GKRS (7.13cm3, SD=8.99cm3), 2 years post-GRS (3.27cm3, SD=3.37cm3), and at last follow up (LFU) (2.79cm3, SD=2.79cm3). The mean percent change in tumor volume from the earliest time to GKRS was +37.7% (SD=23.1%), from GKRS to 3 months post-GKRS was +0.88% (SD=19.4%), from GKRS to 2 year follow up was -26.82% (SD=19.3%), and from GKRS to last follow up was -40.1% (SD=24.6%). After linear regression analysis a larger tumor volume at GKRS was significantly associated with less tumor volume change at 2 years post-GKRS (slope= -1.21, CI: -2.38, -0.05), precent change in pre-GKRS tumor volume, age, gender, and race were not associated with 2 year post-GKRS tumor volume change.
Conclusion: We demonstrated that tumor size at the time of GKRS has a significant negative association (b=-1.21, p=0.04) with change in tumor volume following GKRS. Our cohort had high tumor control with 97.4% of patients having tumor control after GKRS. The mean change in volume at the last follow up compared to GKRS date was -40.1%. We did not find an association with pre-treatment growth rate and change in tumor volume following GKRS. Our study suggest GKRS has high tumor control rates for incidental meningiomas and larger meningiomas have less shrinkage in tumor volume following GKRS.
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