Laser Interstitial Thermal Therapy Treatment Research Articles

DISP-01. FACTORS AFFECTING POST-ABLATION OUTCOMES AND TRIAL ENROLLMENT IN DIVERSE PATIENTS UNDERGOING LASER INTERSTITIAL THERMAL THERAPY

Abstract BACKGROUND Laser interstitial thermal therapy (LITT) is a surgical treatment for progressive brain metastases (BM) following stereotactic radiosurgery (SRS). Although LITT has been increasingly accepted, little is known regarding factors influencing presentation and outcomes of patients with diverse backgrounds. METHODS Retrospective review of all patients receiving their index LITT treatment for BM at a single center from 2015 – 2023. Patient demographics and geospatial data was used to compare differences in receipt of LITT by race or ethnicity, survival outcomes, and clinical trial enrollment. RESULTS From 2015-2023, 137 patients presented for LITT to 146 intracranial lesions. One hundred and six patients (77.3%) were non-Hispanic White (NHW), while among Hispanic or non-White (HNW) patients, 25 (18.2%) were Black or African American, 5 (3.6%) were Asian American, and 1 (0.7%) was Hispanic/Latino. Among HNW patients, women more frequently received LITT (p = 0.022), with skin cancers being a more frequent indication among NHW patients (P = 0.019). NHW patients traveled a median of 62.0 (6.2 – 1045.9) miles to receive LITT vs 25.9 (1.31 – 238.3) miles for HNW patients (p = 0.001). Length of stay, discharge location, or readmission rates did not differ between groups. In multivariate analyses, probability of clinical trial enrollment was less among those of female sex (P = 0.049), HNW race/ethnicity (P = 0.041), or external referral status (P = 0.035), while post-LITT overall survival was predicted by pre-LITT KPS (P = 0.0007) and recurrent tumor on biopsy (P = 0.0002). CONCLUSIONS Differences in presentation for LITT by race or ethnicity may be influenced by underlying patient factors, including sex, systemic disease histology, and distance from a treating center, which do not influence post-LITT procedural outcomes or survival. Accordingly, clinical trial enrollment should be prioritized for vulnerable patient populations to realize the full benefits of laser ablation.

TMIC-12. LITT RESULTS IN ROBUST T CELL INFILTRATION WITHIN THE TUMOR MICROENVIRONMENT IN A BRAIN METASTASIS MURINE MODEL

Abstract INTRODUCTION Laser interstitial thermal therapy (LITT) is a novel minimally invasive neurosurgical technique used to ablate intra-axial brain tumors with real-time thermometry. The impact of LITT on the brain metastatic tumor microenvironment (TME) is unknown in patients due to limitations of tumor tissue collection post-LITT. The primary objective of this study was to describe the kinetics of immunologic infiltration within the TME in a melanoma brain metastasis model. METHOD: C57BL6 mice underwent intra-cranial implantation of B16F10-OVA tumor cells and treated with LITT using a custom-made murine LITT system developed in our laboratory. The tumors were treated to 42°C (near infra-red 1064 nm DPSS laser system) 7 days post-surgery. Tumors were collected 2 days and 10 days post-LITT for immune-phenotyping using flow cytometry. Blood was collected 6 h and 48 h post-LITT to perform the ELISA for IFN-g and TNF-a. RESULTS LITT treatment triggered a cascade of local infiltration of immune cells at different time points. 2-days post-LITT resulted in increased CD8 T cells (p<0.05), macrophage (p<0.05) and microglia infiltration (p<0.01) within the TME compared to control and sham surgery animals. By 10 days after LITT, significant infiltration by CD8 T cells (p<0.0001) and M1 macrophages (p<0.0001) was observed. The CD8 T cells were T central memory (TCM) and T effector memory (TEM). Moreover, comparison between 2 days and 10 days after LITT revealed significant increase of TEM (p<0.0001) and TCM (p<0.001) 10 days post-LITT. In an ELISA assay, non-significant differences were observed in IFN-g and TNF-a level at 48 h. CONCLUSIONS LITT enhances the recruitment of cytotoxic CD8 T cells within TME in a time-dependent manner. The ability of LITT to recruit TCM and TEM to the TME strongly support its potential therapeutic benefit, especially in the context of immunotherapy.

Laser interstitial thermal therapy (LITT) for pediatric low-grade glioma—case presentations and lessons learned

BackgroundThe surgical treatment of brain tumors has developed over time, offering customized strategies for patients and their specific lesions. One of the most recent advances in pediatric neuro-oncological surgery is laser interstitial thermal therapy (LITT). However, its effectiveness and indications are still being evaluated. The aim of this work is to review the current literature on LITT for pediatric low-grade gliomas (pLGG) and evaluate our initial results in this context.MethodsWe retrospectively reviewed our pediatric neurosurgery database for patients who received LITT treatment between November 2019 and December 2023. We collected data on the indications for LITT, technical issues during the procedure, and clinical and radiological follow-up.ResultsThree patients underwent 5 LITT procedures for pLGG. The lesion was thalamo-peduncular in one patient, cingulate in one, and deep parietal in one patient. Two patients had a previous open resection done and were diagnosed with pLGG. One patient underwent a stereotaxic biopsy during the LITT procedure that was non-diagnostic. The same patient underwent a later open resection of the tumor in the cingulate gyrus. There were no surgical complications and all patients were discharged home on the first post-operative day. The follow-up period was between 20 and 40 months. Radiological follow-up showed a progressive reduction of the tumor in patients with LGG.ConclusionLaser interstitial thermal therapy is a minimally invasive treatment that shows promise in treating deep-seated pLGG in children. The treatment has demonstrated a reduction in tumor volume, and the positive results continue over time. LITT can be used as an alternative treatment for tumors located in areas that are difficult to access surgically or in cases where other standard treatment options have failed.

Small pretreatment lesion size and high sphericity as favorable prognostic factors after laser interstitial thermal therapy in brain metastases.

The objective of this study was to identify baseline clinical and radiological characteristics of brain metastases (BMs) associated with a higher probability of lesion-specific progression-free survival (PFS-L) after laser interstitial thermal therapy (LITT). A total of 47 lesions in 42 patients with BMs treated with LITT were retrospectively examined, including newly diagnosed BM, suspected recurrent BM, and suspected radiation necrosis. The association of baseline clinical and radiological features with PFS-L was assessed using survival analyses. Radiological features included lesion size measurements, diffusion and perfusion metrics, and sphericity, which is a radiomic feature ranging from 1 (perfect sphere) to 0. The probability of PFS-L for the entire cohort was 88.0% at 3 months, 70.6% at 6 months, 67.4% at 1 and 2 years, and 62.2% at 3 years. For lesions progressing after LITT (n = 13), the median time to progression was 3.9 months, and most lesions (n = 11) progressed within 6 months after LITT. In lesions showing response to LITT (n = 17), the median time to response was 12.1 months. All 3 newly diagnosed BMs showed a long-term response. The mean (± SD) follow-up duration for all censored lesions (n = 34) was 20.7 ± 19.4 months (range 12 days to 6.1 years). The mean pretreatment enhancing volume was 2.68 cm3 and the mean sphericity was 0.70. Pretreatment small enhancing volume (p = 0.003) and high sphericity (p = 0.024) computed from lesion segmentation predicted a longer PFS-L after LITT. Lesions meeting optimal cutoffs of either enhancing volume < 2.5 cm3 (adjusted p = 0.004) or sphericity ≥ 0.705 (adjusted p = 0.019) had longer PFS-L, and their probability of PFS-L was 86.8% at 3 years. Lesions meeting both cutoffs showed a cumulative benefit (p < 0.0001), with a 100% probability of PFS-L at 3 years, which was unchanged at the end of follow-up (4.1 years). Manually computed estimates of lesion size (maximal axial diameter, p = 0.011) and sphericity (p = 0.043) were also predictors of PFS-L. Optimal cutoffs of diameter < 2 cm (adjusted p = 0.035) or manual sphericity ≥ 0.91 (adjusted p = 0.092) identified lesions with longer PFS-L, and lesions meeting both cutoffs showed a cumulative benefit (p = 0.0023). Baseline diffusion imaging did not predict PFS-L. A subset of lesions (n = 7) with highly perfused hotspots had worse PFS-L (adjusted p = 0.010), but perfusion signal contamination from vessels and cortex and underlying size differences were possible confounders. Small size and high sphericity are ideal baseline features for lesions considered for LITT treatment, with a cumulative PFS-L benefit when both features are present, that could aid patient selection.

Meta-analysis of the impact of laser interstitial hyperthermia on wound healing complications in brain tumors.

High-grade gliomas (HGGs) may be amenable to the neurosurgical technique known as laser interstitial thermal therapy (LITT), which delivers thermal energy to interstitial brain injuries and wounds with pinpoint accuracy. The purpose of this extensive meta-analysis was to evaluate the effects of LITT on wound complications among patients who have brain tumours. Diverse conclusions emerge from a systematic review of pertinent studies, necessitating a comprehensive examination. The meta-analysis, performed utilizing the meta library provided by the R package meta, reveals an initial significant overall effect (RR: -2.1262, 95% CI [-2.7466, -1.5059], p < 0.0001) accompanied by considerable heterogeneity among studies (I2 = 61.13%). Following analyses that specifically examined the incidence of wounds, a complex correlation was found (RR: 0.0471, 95% CI [0.0264, 0.0842], p < 0.0001), indicating that LITT has a discernible but insignificant effect on the occurrence of wounds. Although the meta-analysis emphasizes a notable decrease in wound complications subsequent to LITT treatment, additional research is warranted due to constraints in standardized reporting, data accessibility, and small sample sizes. The results of this study underscore the need for exhaustive protocols to analyse wound complications in patients with brain tumours undergoing LITT.

Modeling for neurosurgical laser interstitial thermal therapy with and without intracranial recording electrodes

Laser thermal ablation has become a prominent neurosurgical treatment approach, but in epilepsy patients it cannot currently be safely implemented with intracranial recording electrodes that are used to study interictal or epileptiform activity. There is a pressing need for computational models of laser interstitial thermal therapy (LITT) with and without intracranial electrodes to enhance the efficacy and safety of optical neurotherapies. In this paper, we aimed to build a biophysical bioheat and ray optics model to study the effects of laser heating in the brain, with and without intracranial electrodes in the vicinity of the ablation zone during the LITT procedure. COMSOL Multiphysics finite element method (FEM) solver software was used to create a bioheat thermal model of brain tissue, with and without blood flow incorporation via Penne's model, to model neural tissue response to laser heating. We report that the close placement of intracranial electrodes can increase the maximum temperature of the brain tissue volume as well as impact the necrosis region volume if the electrodes are placed too closely to the laser coupled diffuse fiber tip. The model shows that an electrode displacement of 4 mm could be considered a safe distance of intracranial electrode placement away from the LITT probe treatment area. This work, for the first time, models the impact of intracranially implanted recording electrodes during LITT, which could improve the understanding of the LITT treatment procedure on the brain's neural networks a sufficient safe distance to the implanted intracranial recording electrodes. We recommend modeling safe distances for placing the electrodes with respect to the infrared laser coupled diffuse fiber tip.

Development of a Treatment Planning Framework for Laser Interstitial Thermal Therapy (LITT).

Develop a treatment planning framework for neurosurgeons treating high-grade gliomas with LITT to minimize the learning curve and improve tumor thermal dose coverage. Deidentified patient images were segmented using the image segmentation software Materialize MIMICS©. Segmented images were imported into the commercial finite element analysis (FEA) software COMSOL Multiphysics© to perform bioheat transfer simulations. The laser probe was modeled as a cylindrical object with radius 0.7 mm and length 100 mm, with a constant beam diameter. A modeled laser probe was placed in the tumor in accordance with patient specific patient magnetic resonance temperature imaging (MRTi) data. The laser energy was modeled as a deposited beam heat source in the FEA software. Penne's bioheat equation was used to model heat transfer in brain tissue. The cerebrospinal fluid (CSF) was modeled as a solid with convectively enhanced conductivity to capture heat sink effects. In this study, thermal damage-dependent blood perfusion was assessed. Pulsed laser heating was modeled based on patient treatment logs. The stationary heat source and pullback heat source techniques were modeled to compare the calculated tissue damage. The developed bioheat transfer model was compared to MRTi data obtained from a laser log during LITT procedures. The application builder module in COMSOL Multiphysics© was utilized to create a Graphical User Interface (GUI) for the treatment planning framework. Simulations predicted increased thermal damage (10-15%) in the tumor for the pullback heat source approach compared with the stationary heat source. The model-predicted temperature profiles followed trends similar to those of the MRTi data. Simulations predicted partial tissue ablation in tumors proximal to the CSF ventricle. A mobile platform-based GUI for bioheat transfer simulation was developed to aid neurosurgeons in conveniently varying the simulation parameters according to a patient-specific treatment plan. The convective effects of the CSF should be modeled with heat sink effects for accurate LITT treatment planning.

NEIM-12 PRE- AND POST-TREATMENT RADIOLOGIC FEATURES AND VOLUMETRIC CHANGES LINKED TO TREATMENT RESPONSE OF BRAIN METASTASES AFTER LASER INTERSTITIAL THERMAL THERAPY (LITT)

Abstract OBJECTIVE To identify pre-treatment imaging features of brain metastases (BM) associated with lesion-specific progression free survival (PFS-L) after laser interstitial thermal therapy (LITT) and to report longitudinal volumetric changes following the treatment. METHODS Forty-seven BM treated with LITT were retrospectively examined. BM were followed until clinical progression, radiologic progression according to the modified RANO criteria, or censoring. The association between imaging features and PFS-L was assessed with survival analyses. Post-LITT volume shrinkage over time was fit to an exponential decay model. RESULTS Thirteen BM progressed after LITT (median time to progression 3.9 months), seventeen met radiologic criteria for response after LITT (median time to response 12.1 months), and seventeen were stable at time of censoring. Median follow-up duration for censored BM was 18.5 months. The probability of PFS-L at six months (PFS6) was 70.6% for the whole cohort. Pre-LITT enhancing volume &amp;lt;2.5 cc (p=0.0004) and sphericity ≥0.705 (p=0.0026) predicted longer PFS-L (PFS6=86.8%), and BM meeting both cutoffs showed a cumulative benefit (p&amp;lt;0.0001, PFS6=100%). Pre-LITT diffusion imaging did not predict PFS-L, while a subset of lesions (n=7) with highly perfused hotspots had worse PFS-L (p=0.0012). Immediate post-LITT volume was increased compared to pre-LITT (p&amp;lt;0.0001, median increase 80.3%). The percentage of volume increase was not a predictor of PFS-L (p=0.56). In fifteen responding BM (88.2%), the post-LITT volumetric shrinkage over time was described by an exponential decay (R2 ranging 0.92-1.0), and the kinetics of shrinkage was heterogeneous (half-life ranging 0.3-5.4 months). CONCLUSIONS Pre-treatment small size and high sphericity are ideal baseline features for BM considered for LITT treatment and could aid patient selection. Modeling longitudinal volumetric changes of BM responding to LITT is a potential approach to identify BM at risk for progression which deviate from a typical shrinkage pattern.

DDEL-06. HEAT-ACTIVATED DOXORUBICIN UPTAKE FACILITATED BY LASER INTERSTITIAL THERMAL THERAPY

Abstract Although surgery has been shown to provide a survival benefit in patients with glioblastoma multiforme (GBM), tumor location and geometry may restrict maximal resection. Additionally, the margin of resection cavity contains infiltrating tumor cells that result in recurrence and therapy resistance. Laser interstitial thermal therapy (LITT) is a treatment modality that uses thermal energy to destroy tumor cells. LITT is useful for tumors that are not appropriate for conventional surgical resection. Our laboratory has developed a LITT model to study LITT in a genetically engineered mouse model of GBM. The combination of heat activated nanoparticles and LITT represents an opportunity to target the infiltrating tumor margin, extending the treatment penumbra. We hypothesized that heat-activated liposomes containing doxorubicin (ThermoDox, Celsion) would demonstrate infiltration into the brain parenchyma after treatment with LITT. We treated tumor-bearing mice with LITT or sham (laser fiber implanted but not activated) after either ThermoDox (5mg/kg) or PBS infusion, 30 minutes before performing LITT or sham treatment. We euthanized these mice 1 hour after LITT or sham treatment, harvested brains, and performed immunofluorescence to identify doxorubicin in parenchymal cells. Doxorubicin was identified in 100% of mice treated with LITT following ThermoDox administration which is in contrast with groups treated with LITT and PBS, sham and ThermoDox, and sham and PBS. Here, we show that heat-activated nanoparticles are disrupted through hyperthermia followed by the release of doxorubicin only in the presence of hyperthermia, which paves way for the clinical use of ThermoDox as adjunct chemotherapy following LITT in treatment-resistant GBM treatment.

SURG-22. STAGED LASER INTERSTITIAL THERAPY (LITT) FOR THE SURGICAL TREATMENT OF INSULAR GLIOMA: A CASE SERIES WITH A NOVEL TREATMENT PARADIGM

Abstract BACKGROUND Insular gliomas pose a significant surgical challenge due to the insula’s delicate surrounding functional and vascular anatomy. Insular gliomas are conventionally treated with open surgical resection augmented by several surgical adjuvants. Despite advancements in technology and surgical techniques, surgical resection of insular gliomas has been associated with frequent and potentially severe morbidity. Laser interstitial thermal therapy (LITT) is a novel, cytoreductive, and less-invasive treatment option for glioma. OBJECTIVE We describe the first-ever series of patients with insular glioma treated with staged LITT with or without subsequent craniotomy. METHODS A retrospective institutional database identified patients with insular glioma who underwent staged LITT treatments. Clinical, histopathological, and volumetric lesional characteristics were obtained. Procedural characteristics, morbidity, overall survival (OS), and progression-free survival (PFS) were determined. RESULTS Between 2019-2022, 11 patients with insular glioma were treated in stages with a total of 21 LITT procedures with or without subsequent craniotomy. Four patients had Diffuse Astrocytoma (IDHmt/TP53+), one Gemistocytic Astrocytoma (IDHmt/TP53+), three Anaplastic Astrocytoma (IDHmt/TP53+), one Anaplastic Oligodendroglioma (IDHmt/1p19q codel), one secondary GBM (IDHmt/TP53+), and one GBM (IDHwt/TP53-). Six patients were treated with LITT alone, while five patients were treated with LITT followed by a craniotomy for complete resection. Patients had a median tumor volume of 31.5 cm3 (9.58, 97) and a mean extent of ablation±resection of 97.68% (S.D. 5.4). At a median follow-up of 12.59 months, patients had a median PFS of 12.88 months and an OS of 14.46 months. No patients had a change in KPS following LITT. Two patients had a decrease in KPS following surgery. CONCLUSION We present the first-ever reported series of insular glioma treated with staged LITT with/without subsequent resection. We found that staged treatment of insular gliomas with LITT is safe, effective, and a minimally invasive option that avoids the potentially significant morbidity associated with conventional surgery.

Nanoparticle-assisted, image-guided laser interstitial thermal therapy for cancer treatment.

Laser interstitial thermal therapy (LITT) guided by magnetic resonance imaging (MRI) is a new treatment option for patients with brain and non‐central nervous system (non‐CNS) tumors. MRI guidance allows for precise placement of optical fiber in the tumor, while MR thermometry provides real‐time monitoring and assessment of thermal doses during the procedure. Despite promising clinical results, LITT complications relating to brain tumor procedures, such as hemorrhage, edema, seizures, and thermal injury to nearby healthy tissues, remain a significant concern. To address these complications, nanoparticles offer unique prospects for precise interstitial hyperthermia applications that increase heat transport within the tumor while reducing thermal impacts on neighboring healthy tissues. Furthermore, nanoparticles permit the co‐delivery of therapeutic compounds that not only synergize with LITT, but can also improve overall effectiveness and safety. In addition, efficient heat‐generating nanoparticles with unique optical properties can enhance LITT treatments through improved real‐time imaging and thermal sensing. This review will focus on (1) types of inorganic and organic nanoparticles for LITT; (2) in vitro, in silico, and ex vivo studies that investigate nanoparticles' effect on light–tissue interactions; and (3) the role of nanoparticle formulations in advancing clinically relevant image‐guided technologies for LITT.This article is categorized under:Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological DiseaseImplantable Materials and Surgical Technologies > Nanoscale Tools and Techniques in Surgery

Laser ablation for corpus callosotomy: Systematic review and pooled analysis

PurposeThe Laser interstitial thermal therapy (LITT) technique has been used recently for corpus callosotomy in patients with epilepsy, especially atonic seizures (drop attacks) and Lennox-Gastaut Syndrome (LGS). However, there is little data on safety and outcomes. Therefore, the authors systematically studied and conducted a pooled analysis with special focus on feasibility, outcomes and complications. MethodsA systematic review was performed in accordance with the PRISMA guidelines. A total of 10 retrospective studies were identified, comprising 58 cases of MRI-guided LITT treatment. ResultsMRI-guided LITT was successfully performed in 57 cases while one case was aborted due to hemorrhage. The average duration of clinical follow-up following LITT callosotomy was 20 months. In the 57 LITT callosotomies, complete seizure freedom and excellent seizure control (Engel I and II) were achieved in 21.1% and 49.1% of patients, respectively. For atonic seizures, the rate of complete freedom and excellent control was 52.5% and 72.5%, respectively. The median length of stay at hospital was 2 days. No death was encountered. Common complications included: fiber-related hemorrhage (8.6%), inaccurate placement (6.9%) followed with transient hemiparesis/hemineglect and supplementary motor area (SMA) syndrome 5.2% each. The rate of disconnection syndrome was 3.4%. ConclusionMRI-guided LITT for corpus callosotomy is feasible and safe, with low complication rates, short hospitalization and has comparable rates of seizure control to that of classic surgical callosotomy. The majority of patients with atonic seizures achieve complete seizure freedom and excellent control (Engel I and II). The risk for developing disconnection syndrome is low.

A Single-Institution Retrospective Study of Patients Treated With Laser-Interstitial Thermal Therapy for Radiation Necrosis of the Brain.

ObjectLaser-interstitial thermal therapy (LITT) has been proposed as an alternative treatment to surgery for radiation necrosis (RN) in patients treated with stereotactic radiosurgery (SRS) for brain metastases. The present study sought to retrospectively analyze LITT outcomes in patients with RN from SRS.MethodsThis was a single-institution retrospective study of 30 patients treated from 2011-2018 with pathologically-proven RN after SRS for brain metastases (n=28) or proximally treated extracranial lesions treated with external beam radiotherapy (n=2). Same-day biopsy was performed in all cases. Patients were prospectively followed with Functional Assessment of Cancer Therapy - Brain (FACT-Br), EuroQol-5 Dimension (EQ-5D), Hopkins Verbal Learning Test (HVLT) and clinical history and examination. Adjusted means, standard errors and tests comparing visits to pre-LITT were generated. Kaplan-Meier method was used to estimate time overall survival. Competing risk analysis was used to estimate cumulative incidence of LITT failure.ResultsIn our patient population, median time from radiotherapy to LITT was 13.1 months. Median SRS dose and median LITT treatment target volume were 20 Gy (IQR 18-22) and 3.5 cc (IQR 2.2-4.6), respectively. Seventy-seven percent of our patients tapered off steroids within one month. There were only two instances of RN recurrence after LITT, with recurrence defined as recurrence of symptoms after initial improvement. These recurrences occurred at 1.9 and 3.4 months. The three-, six- and nine-month freedom from recurrence rates were 95.7%, 90.9%, and 90.9%. Median survival in our patient population with pathologically confirmed RN treated with LITT was 2.1 years. Regarding the quality of life questionnaires with which some patients were followed as part of different prospective studies, completion rates were 22/30 for FACT-Br, 16/30 for the EQ-5D and 8/30 for HVLT. Quality of life questionnaire results were overall stable from baseline. Mean FACT-Br scores were stable from baseline (17.9, 16.6, 21.4 and 22.8) to three months (18.8, 15.4, 18.4 and 23.4) (p=0.38, 0.53, 0.09 and 0.59). The mean EQ-5D Aggregate score was stable from baseline (7.1) to one month (7.6) (p=0.25). Mean HVLT-R Total Recall was stable from baseline (20.6) to three months (18.4) (p=0.09). There was a statistically significant decrease in mean Karnofsky Performance Scale (KPS) score from baseline (84) to three-month follow-up (75) (p=0.03).ConclusionsLITT represents a safe and durably effective treatment option for RN in the brain. Results demonstrate a median survival of 2.1 years from LITT with only two recurrences, both within four months of treatment and salvageable. Patient-reported outcomes showed no severe declines after LITT. Quality of life questionnaires demonstrated stable well-being and functionality from baseline. LITT should be considered for definitive treatment of RN, especially in cases where patients have significant side effects from standards medical therapies such as steroids or if steroids are minimally effective.

Laser interstitial thermal therapy as an adjunct therapy in brain tumors: A meta-analysis and comparison with stereotactic radiotherapy.

Background: Minimally invasive procedures are gaining widespread acceptance in difficult-to-access brain tumor treatment. Stereotactic radiosurgery (SRS) is the preferred choice, however, laser interstitial thermal therapy (LITT) has emerged as a tumor cytoreduction technique. The present meta-analysis compared current SRS therapy with LITT in brain tumors.Methods: A search was performed in Lilacs, PubMed, and Cochrane database. Patient’s demographics, tumor location, therapy used, Karnofsky performance status score before treatment, and patient’s outcome (median overall survival, progression-free survival, and adverse events) data were extracted from studies. The risk of bias was assessed by Cochrane collaboration tool.Results: Twenty-five studies were included in this meta-analysis. LITT and SRS MOS in brain metastasis patients were 12.8 months’ versus 9.8 months (ranges 9.3–16.3 and 8.3–9.8; P = 0.02), respectively. In a combined comparison of adverse effects among LITT versus SRS in brain metastasis, we found 15% reduction in absolute risk difference (−0.16; 95% confidence interval P < 0.0001).Conclusion: We could not state that LITT treatment is an optimal alternative therapy for difficult-to-access brain tumors due to the lack of systematic data that were reported in our pooled studies. However, our results identified a positive effect in lowering the absolute risk of adverse events compared with SRS therapy. Therefore, randomized trials are encouraged to ascertain LITT role, as upfront or postoperative/post-SRS therapy for brain tumor treatment.

A Multi-Institutional Analysis of Factors Influencing Surgical Outcomes for Patients with Newly Diagnosed Grade I Gliomas

To assess the impact of intraoperative magnetic resonance imaging (iMRI), extent of resection (EOR), and other factors on overall survival (OS) and progression-free survival (PFS) for patients with newly diagnosed grade I gliomas. A multicenter database was queried to identify patients with grade I gliomas. Retrospective analyses assessed the impact of patient, treatment, and tumor characteristics on OS and PFS. A total of 284 patients underwent treatment for grade I gliomas, including 248 resections (205 with iMRI, 43 without), 23 biopsies, and 13 laser interstitial thermal therapy treatments. Log-rank analyses of Kaplan-Meier plots showed improved 5-year OS (P= 0.0107) and PFS (P= 0.0009) with increasing EOR, and a trend toward improved 5-year OS for patients with lower American Society of Anesthesiologists score (P= 0.0528). Greater EOR was associated with significantly increased 5-year PFS for pilocytic astrocytoma (P < 0.0001), but not for ganglioglioma (P= 0.10) or dysembryoplastic neuroepithelial tumor (P= 0.57). Temporal tumors (P= 0.04) and location of "other" (P= 0.04) were associated with improved PFS, and occipital/parietal tumors (P= 0.02) were associated with decreased PFS compared with all other locations. Additional tumor resection was performed after iMRI in 49.7% of cases using iMRI, which produced gross total resection in 64% of these additional resection cases. Patients with grade I gliomas have extended OS and PFS, which correlates positively with increasing EOR, especially for patients with pilocytic astrocytoma. iMRI may increase EOR, indicated by the rate of gross total resection after iMRI use but was not independently associated with increased OS or PFS.

SURG-29. LASER INTERSTITIAL THERMAL THERAPY COMPARED TO CRANIOTOMY FOR TREATMENT OF RECURRENT GLIOBLASTOMA

Abstract There have been publications that propose the use of laser interstitial thermal therapy (LITT) as a viable alternative to craniotomy for the treatment of glioblastoma (GBM). The aim of this study was to retrospectively compare outcomes after LITT versus craniotomy for patients with recurrent GBM. To adequately match the cohorts, we included only pre-treatment tumor volumes of under 15 cc. We retrospectively collected data on all patients presenting with recurrent GBM, with a recurrence volume under 15 cc. These patients were either treated with LITT or craniotomy by the senior author. Data included demographics, tumor location and volume, tumor markers, perioperative complications, re-initiation of adjuvant chemotherapy, and long-term follow up data. We performed 23 LITT treatments and 34 craniotomies for recurrent GBM in patients that met selection criteria. There was no significant difference in the patients’ age, tumor volume (6.38 for craniotomy versus 5.765 cc for LITT), location, and post-procedure KPS. Patients that underwent LITT had significantly reduced inpatient stays in comparison to craniotomy (1.7 versus 4.2 days). They also had less perioperative complications (13.0% versus 32.3% for craniotomy). It was found that 28 out of the 34 patients that underwent craniotomy were able to undergo adjuvant therapy; in comparison, 15 out of the 23 patients who underwent LITT had undergone adjuvant therapy. Of these patient’s that underwent adjuvant therapy, 87% of patients were able to receive bevacizumab or a clinical trial versus 42% after craniotomy. Progression-free survival (PFS) and overall survival (OS) after procedure were similar for LITT versus craniotomy, respectively: % PFS-survival at 6 months = 23.5% versus 21.7%. Overall survival did not significantly differ at 9 months versus 9.9 months respectively. LITT appears to be safe and may be as efficacious as craniotomy in achieving progression free survival for small to moderate volume recurrent GBM.

Laser Interstitial Thermal Therapy to the Posterior Fossa: Challenges and Nuances

Abstract INTRODUCTION Posterior fossa tumors are rare in adults and pose a challenge to treat due to the bony contour of the posterior fossa, complex anatomical structures including deep venous sinuses, and the proximity of the fourth ventricle and brain stem. We describe our experience with laser interstitial thermal therapy (LITT) for the management of brain metastases and radiation necrosis of the posterior fossa. METHODS We retrospectively analyzed 13 patients with metastases and radiation necrosis of the posterior fossa managed with LITT. Patient data were extracted from the electronic medical record along with magnetic resonance images (MRI) preoperatively, immediately postoperatively, and at each follow-up. RESULTS Thirteen patients with histopathologically confirmed radiation necrosis (n = 5) and metastases (n = 8) of the posterior fossa underwent LITT. The median preoperative tumor and postoperative ablation cavity volume was 4.66 and 6.29 cm3, respectively. The median volume of the ablation cavity decreased to 2.90 cm3 at 9-mo follow-up. The median volume of peritumoral edema was 12.25 cm3, which fell to a median 5.77 cm3 at 1-mo follow-up. Median progression-free survival was 7 mo (range 3-14 mo) from LITT. The mean overall survival (OS) was 40 months (range 2-49 mo). There were no intraoperative complications. One patient experienced palsy of the seventh and eighth cranial nerves on follow-up, attributable to LITT. Two patients received 2 LITT treatments for their respective lesions. CONCLUSION Lesions of the posterior fossa are challenging to treat given their proximity to the dura and venous sinuses. We demonstrate that LITT ablation may be a safe and feasible option for metastases and radiation necrosis of the posterior fossa. Larger studies are needed to confirm the efficacy of this approach.

Glioblastoma Treated With Magnetic Resonance Imaging-Guided Laser Interstitial Thermal Therapy: Safety, Efficacy, and Outcomes.

BACKGROUNDDespite the multitude of available treatments, glioblastoma (GBM) remains an aggressive and uniformly fatal tumor. Laser interstitial thermal therapy (LITT) is a novel, minimally invasive treatment that holds promise for treating patients with GBM who are not candidates for traditional open craniotomy. However, due to the recent introduction of LITT into clinical practice, large series that evaluate safety and long-term outcomes after LITT are lacking.OBJECTIVETo present our institution's series of over 50 GBM patients treated with LITT, with regard to safety, efficacy, and outcomes.METHODSWe performed a retrospective descriptive study of patients with histologically proven GBM who underwent LITT. Data collected included demographics, tumor location and volume, tumor genetic markers, treatment volume, perioperative complications, and long-term follow-up data.RESULTSWe performed 58 LITT treatments for GBM in 54 patients over 5.5 yr. Forty-one were recurrent tumors while 17 were frontline treatments. Forty GBMs were lobar in location, while 18 were in deep structures (thalamus, insula, corpus callosum). Average tumor volume was 12.5 ± 13.4 cm3. Average percentage of tumor treated with the yellow thermal damage threshold (TDT) line (dose equivalent of 43°C for 2 min) was 93.3% ± 10.6%, and with the blue TDT line (dose equivalent of 43°C for 10 min) was 88.0% ± 14.2%. There were 7 perioperative complications (12%) and 2 mortalities (3.4%). Median overall survival after LITT for the total cohort was 11.5 mo, and median progression-free survival 6.6 mo.CONCLUSIONLITT appears to be a safe and effective treatment for GBM in properly selected patients.

Cerebral edema induced by laser interstitial thermal therapy and radiotherapy in close succession in patients with brain tumor.

Laser interstitial thermal therapy (LITT) is an image-guided technique that uses high temperature to ablate pathological tissue. Brain tumor patients undergoing LITT may also undergo radiation therapy (RT) either before or after LITT. Both procedures have been reported to increase cerebral edema and thereby the two treatments in close succession may worsen existing edema that can be difficult to control. The purpose of our study was to determine the frequency of increased and/or symptomatic cerebral edema after combined LITT and RT, the radiographic and clinical signs of this cerebral edema, and the treatment required. This is a single center, retrospective study of patients who underwent LITT and RT less than 60 days apart. Brain Magnetic Resonance Imaging (MRI) and clinical information were reviewed at three time points (pre-treatment, post-LITT, and post-RT). The study cohort comprised eight patients: six with glioblastoma, one with anaplastic astrocytoma, and one with metastasis. Pre-treatment MRI showed cerebral edema in seven patients. Post-LITT MRI showed worsening cerebral edema in three patients, of which one was symptomatic. Post-RT MRI showed worsening cerebral edema in one patient. One patient who received RT before LITT had asymptomatic cerebral edema post-RT that improved post-LITT. Three patients required prolonged steroid therapy (>65 days), while two patients required bevacizumab for steroid-refractory edema. LITT and RT treatment in close succession can induce cerebral edema, which can usually be managed successfully with steroids, although the treatment period may be prolonged. A minority of patients may require more aggressive treatment, such as bevacizumab. Lasers Surg. Med. 50:917-923, 2018. © 2018 Wiley Periodicals, Inc.

Volumetric response of progressing post-SRS lesions treated with laser interstitial thermal therapy.

We analyzed volumetric response of metastatic brain tumors that progressed despite treatment with stereotactic radiosurgery (SRS) after treatment with laser interstitial thermal therapy (LITT). We retrospectively reviewed consecutive patients treated from 1/2012 to 10/2015 with LITT for metastatic brain tumors demonstrating progression after SRS. Volumes were quantified using MRI with contrast-enhanced T1-weighted (T1W) and fluid-attenuated inversion recovery (FLAIR). Fifty lesions from 36 patients were studied. Lesions were assessed prior to LITT, immediately after LITT, 0-90 days after LITT, 90-180 days after LITT, 180-270 days after LITT, and 270-360 days after LITT. The median T1W volume was 5.05cc (range 0.54-23.31cc) before LITT treatment (n = 50), 7.70cc (range 1.72-38.76cc) 0-90 days after LITT (n = 47), and 3.68cc (range 1.282-48.31cc) 180-270 days after LITT (n = 21). The median FLAIR volume was 43.36cc (range 3.09-233.01cc) before LITT treatment (n = 50), 37.13cc (range 3.48-244.23cc) 0-90 days after LITT (n = 43), 31.68cc (range 1.6-248.75cc) 180-270 days after LITT (n = 18). The 6-month FLAIR volume showed a statistically significant reduction compared to pretreatment (p = 0.04). After selecting for cases where patients had two or more post-operative MRIs, we found that 24 lesions (63%) demonstrated an overall downward trend and 14 lesions (37%) demonstrated an upward trend. The median pre-treatment T1W volume for the patients whose lesions demonstrated volumetric reduction after LITT was 3.54cc (range 0.539-10.06cc) and for those who did not demonstrate volumetric reduction after LITT it was 8.81cc (range 0.926-23.313cc). The pre-treatment tumor volume plays a significant role in determining response to LITT with smaller tumor volumes responding better to LITT than tumors with larger volumes.