Application of Laser Interstitial Thermal Therapy in Insular Gliomas

Research Background and Problem Statement

The management of insular gliomas has always faced significant surgical challenges. Due to the complex functional and vascular anatomy surrounding the insula, maximally safe resection is highly technically challenging. Removing low-grade and high-grade insular gliomas via transcortical or transcallosal approaches can improve overall survival (OS), progression-free survival (PFS), malignant progression-free survival, and seizure control. However, despite advances in microsurgical techniques, intraoperative localization, and other adjuncts (such as intraoperative MRI or 5-aminolevulinic acid), resection of insular tumors remains associated with significant morbidity and low rates of achieving gross total resection.

Laser Interstitial Thermal Therapy (LITT) is a novel, precise, and minimally invasive ablative treatment option suitable for insular glioma patients. LITT can effectively treat both low-grade and high-grade gliomas while selectively targeting tumor tissue and preserving critical surrounding vasculature and functional tracts, facilitating maximal safe treatment of insular gliomas. However, to date, the application of LITT for insular gliomas has been limited to individual case reports. This study aims to share our experience with LITT for insular gliomas and propose a management model incorporating LITT into the overall surgical framework for insular gliomas.

Paper Source

This paper is authored by Hassan A. Fadel, Jacob A. Pawloski, Anthony J. Anzalone, Sameah Haider, Lonni R. Schultz, Steven N. Kalkanis, Adam M. Robin, and Ian Y. Lee from the Department of Neurosurgery and Public Health Sciences at Henry Ford Hospital and the Department of Neurosurgery at the University of Miami. The paper was published online in the Journal of Neurosurgery on May 24, 2024, with the DOI: 10.³¹⁷¹⁄₂₀₂₄.2.JNS232807.

Research Methods

The research team used a prospectively collected single-institution database to identify patients diagnosed with insular gliomas and treated with LITT between 2015 and 2023. The study not only details the proposed framework for insular glioma management but also highlights treatment indications, principles, and technical nuances through illustrative case examples.

They categorized tumors based on size and extent into those confined to the insula versus those with additional temporal or frontal involvement (Insular+), with the former receiving single or staged LITT and the latter undergoing LITT combined with conventional craniotomy and tumor resection.

The study cohort included 22 newly diagnosed insular glioma patients among 261 patients, encompassing 33 LITT procedures. Patients were divided into Insular and Insular+ groups, with detailed analysis of clinical and pathological characteristics, treatment outcomes, and safety for each case.

Results and Findings

Outcomes for Insula-Confined Tumors

Of the 22 patients, 12 had tumors confined to the insula and underwent LITT. Their median tumor volume was 13.4 cm³ (IQR 10.6, 26.3 cm³), with a median treatment extent of 100% (IQR 92.1%, 100%). These patients were discharged within one day after surgery, demonstrating the low inpatient demand of LITT.

Outcomes for Insular+ Tumors

In contrast, the 10 patients with Insular+ tumors had larger median tumor volumes (81.2 cm³, IQR 51.9, 97 cm³) and median treatment extent of 96.6% (IQR 93.7%, 100%). These patients had significantly longer hospital stays, with 50% staying more than 3 days.

During follow-up after treatment, two cases of tumor progression were observed: one WHO grade IV glioblastoma and one unspecified diffuse glioma. Additionally, higher rates of permanent neurological deficits were seen in high-grade tumors, such as 43% in grade IV tumors, and more significant declines in postoperative Karnofsky Performance Status scores (p=0.046).

Conclusions and Significance

The study demonstrates the feasibility of incorporating LITT as part of the management of insular gliomas, potentially reducing tumor volume while mitigating risks associated with conventional surgery. It highlights the potential advantage of LITT in avoiding surgical risks constrained by the complex vasculature and functional tracts surrounding the insula. Furthermore, it emphasizes the need for an integrated management framework combining LITT and surgery, particularly for high-grade tumors requiring individualized treatment strategies.

Research Highlights

1. Novelty and Precision: LITT, as a newer and precise treatment modality, can effectively reduce tumor volume while preserving surrounding functional structures.
2. Flexibility of Staged Treatment: The proposed strategy of staged LITT for larger tumors demonstrates its flexibility in addressing complex clinical scenarios.
3. Lower Inpatient Demand: Shorter hospital stays after LITT treatment highlight its minimally invasive nature and rapid recovery.

Limitations of the Study

The study sample size is relatively small, and long-term survival data analysis is lacking. Although the longest follow-up is 1261 days, meaningful survival analysis cannot be performed for nearly 40% of low-grade tumor patients. Thus, larger-scale studies with longer follow-up are needed to evaluate the long-term effects of LITT for insular gliomas.

This study provides valuable experience to guide future clinical research exploring the application of LITT in the treatment of insular gliomas, with the hope of bringing new treatment options for patients with these challenging tumors.