Fractionated Gamma Knife radiosurgery for skull base meningiomas: a single-institution experience

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>Gamma Knife radiosurgery (GKRS) has been successfully used for the treatment of intracranial meningiomas given its steep dose gradients and high-dose conformality. However, treatment of skull base meningiomas (SBMs) may pose significant risk to adjacent radiation-sensitive structures such as the cranial nerves. Fractionated GKRS (fGKRS) may decrease this risk, but until recently it has not been practical with traditional pin-based systems. This study reports the authors’ experience in treating SBMs with fGKRS, using a relocatable, noninvasive immobilization system.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>The authors performed a retrospective review of all patients who underwent fGKRS for SBMs between 2013 and 2018 delivered using the Extend relocatable frame system or the Icon system. Patient demographics, pre- and post-GKRS tumor characteristics, perilesional edema, prior treatment details, and clinical symptoms were evaluated. Volumetric analysis of pre-GKRS, post-GKRS, and subsequent follow-up visits was performed.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>Twenty-five patients met inclusion criteria. Nineteen patients were treated with the Icon system, and 6 patients were treated with the Extend system. The mean pre-fGKRS tumor volume was 7.62 cm<jats:sup>3</jats:sup> (range 4.57–13.07 cm<jats:sup>3</jats:sup>). The median margin dose was 25 Gy delivered in 4 (8%) or 5 (92%) fractions. The median follow-up time was 12.4 months (range 4.7–17.4 months). Two patients (9%) experienced new-onset cranial neuropathy at the first follow-up. The mean postoperative tumor volume reduction was 15.9% with 6 patients (27%) experiencing improvement of cranial neuropathy at the first follow-up. Median first follow-up scans were obtained at 3.4 months (range 2.8–4.3 months). Three patients (12%) developed asymptomatic, mild perilesional edema by the first follow-up, which remained stable subsequently.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>fGKRS with relocatable, noninvasive immobilization systems is well tolerated in patients with SBMs and demonstrated satisfactory tumor control as well as limited radiation toxicity. Future prospective studies with long-term follow-up and comparison to single-session GKRS or fractionated stereotactic radiotherapy are necessary to validate these findings and determine the efficacy of this approach in the management of SBMs.</jats:p></jats:sec>

Surgical and Functional Outcome after Resection of 64 Petroclival Meningiomas

“…While single-fraction treatment of small lesions is both effective for controlling tumors and sparing OARs, it can be a considerable challenge to balance tumor control and radiation-induced toxicity for larger tumors, especially skull base tumors. Hypofractionated Gamma Knife Radiosurgery (e.g., 25 Gy in 5 fractions) can optimize said balance of tumor control and normal tissue toxicity in comparison to single-fraction radiosurgery [ 40 , 43 , 44 , 45 ].…”

Hypofractionated Gamma Knife Radiosurgery: Institutional Experience on Benign and Malignant Intracranial Tumors

“…Hence, we devised our protocol on the basis of the few studies in the literature that reported favorable outcomes in treating intracranial tumors (26,27). The reported number of fractions ranged from 3 to 5, and the between-fraction time interval from days to months, depending on the center experience and lesion characteristics (28). In our cohort, we delivered 3 or 5 GKRS fractions per-patient, with a median dose of 6 Gy (range=4.7-6.7 Gy), which has been correlated with good tumor control (27).…”

Dosimetric evaluation of adult and paediatric brain tumours planned using mask‐based cobalt‐60 fractionated stereotactic radiotherapy compared to linear accelerator‐based volumetric modulated arc therapy

“…4 However, our study is unique because we evaluated a novel mcfSRT system and demonstrated dosimetric feasibility in the setting of conventionally fractionated treatment. Prior reports of using the Leksell Gamma Knifeâ Icon TM for fractionated radiotherapy have been limited to short courses of RT over 5 fractions or less; [14][15][16][17] there are no known published reports of treatment courses over prolonged fractionation schedules using this device, though retrospective work to evaluate such treatments is ongoing (Dr Michael Yan, 2022, personal communication).…”