Speakers

Impact of postoperative Stereotactic Radiosurgery on SpenoOrbital Meningiomas patient’s outcome.
1109 16:10-16:20
AASNS & WANS Joint Seminar/305
Background: Spheno-orbital meningiomas (SOM) are known to invaded critical skull base areas. The authors report a series of WHO I SOM, propose a subclassification of this tumor according to its extension to critical positions and analyze the impact of extent of resection and the role of stereotactic radiotherapy in tumor recurrence. Methods: A prospective maintained university medical center registry was utilized to undertake a retrospective review of patients operated with WHO I SOM. Details related to critical skull base region’s extension (supra-orbital fissure, cavernous sinus, orbital apex), extent of resection and adjuvant radiosurgery were collected. Statistical calculations were preformed using IBM SPSS Statistics version 25. A p value <0.05 was considered significant. Survival analysis was performed using Kaplan-Meier survival analysis and the log rank test. Results: A total of 77 patients operated from 2002-2021 were included. There were 65 women (84.4%) and 12 men (15.6%). Mean age at surgery was 54.8 years (median 53 years, range 23−88). Tumors were defined as local in 28 (35.4%) and with extension into the skull base critical structures in 51 (64.6%). GTR was achieved in 35 (44.3%), STR in 40 (50.6%), and PR in four (5.1%). Surgical morbidity was 10%. There was no surgical mortality. 28 patients with less than GTR were treated with adjuvant radiotherapy. A total length of follow up was a mean of 172.3 months. There were 14 recurrences (17.7%), 63 patients (79.7%) had no recurrence, and two patients (2.5%) were lost to follow-up. PFS was significant statistically different in patients with invasive tumors in whom the extent of resection was subtotal, with a longer PFS in patients that were treated with adjuvant radiotherapy. (P value <0.001). Conclusions: SOM could be divided in two groups according to its skull base extension facilitating decision management and outcome prediction. Patients with local WHO I SOM had higher rate of GTR and better PFS than tumors extending to involve critical regions. When less than GTR is achieved postoperative adjuvant radiotherapy is advised if there is evidence of previous tumor growth.

Stereotactic Implantation of Diffusing Alpha-emitters Radiation Therapy Sources in the Swine Brain: A Feasibility and Safety Preclinical Study.
1108 14:10-14:20
Neuro-oncology/305
Background: Diffusing alpha-emitters Radiation Therapy (“Alpha DaRT”) employs a radium-224-loaded source to disperse alpha-emitting atoms within a therapeutic "kill-zone" of a few millimeters, minimizing damage to adjacent healthy tissue. Preclinical studies have demonstrated tumor growth delay in murine models of various cancer types, including glioblastoma multiforme, and the device is in use clinically for patients with skin and head and neck cancer. This study aims to assess the safety and feasibility of implementing Alpha DaRT for brain tumor treatment. . Methods: Using a porcine model, Alpha-DaRT sources were delivered via image-guided stereotactic implantation into both hemispheres of eight swine. A dedicated applicator allowed the delivery of 1-3 clusters of 7 sources through a single penetration point into each hemisphere. A 90-day follow-up period included clinical evaluation, brain MRI, head CT, blood, CSF, urine, and feces sampling, and a three-dimensional analysis of source location over time. Brain tissue pathology was performed on termination. Results: Alpha-DaRT sources were reproducibly and efficiently delivered to the brain cortex and subcortex. No unexpected abnormalities were detected in blood or CSF samples. MRI and CT scans revealed no evidence of major bleeding or infection. Measurements of 212Pb in blood and CSF exhibited the expected exponential decay from day 7 to day 14 post-source implantation. Minimal spatial and temporal movements of the sources were noted. Histopathological analysis demonstrated locally confined findings in the brain parenchyma, proximal to the sources. Conclusions: Alpha-DaRT sources can be safely delivered into a large animal brain using image-guided stereotactic implantation. These findings support further exploration of Alpha DaRT as a potential treatment modality for brain tumors. Keywords: Alpha DaRT, stereotactic implantation, minimally invasive, focal therapy, brain tumors