STEREOTACTIC RADIOSURGERY OF BRAIN MENINGIOMAS: A SERIES OF CLINICAL CASES
Abstract
Relevance: Meningiomas are the most common primary intracranial tumors in adults. Residual tissue frequently remains after surgery, and reoperation carries a risk of permanent neurological deficit, which stereotactic radiosurgery (SRS) helps to avoid. The clinical protocol in force in Kazakhstan specifies a single dose of 14-16 Gy for WHO Grade I meningiomas and permits escalation for Grade II-III without naming a value.The study aimed to describe the technical delivery of a standardized single-fraction dose of 18 Gy for brain meningiomas ≤ 3 cm, the early radiological response, and treatment tolerance in 19 consecutive patients at a single center.Materials and Methods: A single-center consecutive case series (IDEAL stage 2a), retrospective-prospective, 2023-2025; data cutoff 31 December 2025. In 14 of 19 patients, the diagnosis was histologically verified (WHO Grade I – 7, Grade II – 5, Grade III – 2); in 5 patients, the meningioma was diagnosed from MRI without histological confirmation, and no WHO grade was assigned. Treatment was delivered on a TrueBeam STx accelerator and planned in Eclipse 15.6 using VMAT; PTV = GTV + 1 mm, 18 Gy per fraction to the 80% isodose. Patient-specific QA of every plan was performed on ArcCHECK; positioning was verified with OBI and cone-beam CT. Response was assessed using the 2019 RANO criteria for meningioma based on the sum of products of perpendicular diameters.Results: Median follow-up was 15 months (3-22). Seventeen patients completed the 12-month assessment: complete response in 9 (52.9%), partial response in 3 (17.6%), stabilization in 5 (29.4%); the objective response rate was 70.6%. No progression was recorded, although the follow-up period does not allow conclusions about local control. Median brain V12Gy was 3.6 cm³. No CTCAE v.5.0 grade II-IV reactions and no signs of radionecrosis were registered.Conclusion: Single-fraction 18 Gy for meningiomas ≤ 3 cm is technically feasible on a linear accelerator and was not accompanied by significant toxicity within the observed period. The data are descriptive, contain no comparison with the 14–16 Gy range, and do not justify universal use of 18 Gy