Predictors of survival and time to progression following operative management of intramedullary spinal cord astrocytomas

Spinal Intramedullary Tumors

BACKGROUND

Intramedullary tumors are a subgroup of spinal tumors and are associated with high morbidity and mortality. The estimated incidence of spinal tumors in general is 0.74 to 1.6 per 100 000 persons per year, with intramedullary tumors making up 10% to 30% of the total. The diagnosis is often delayed because of the insidious onset of symptoms, which are often nonspecific at first.

METHODS

This review is based on pertinent publications about intramedullary tumors that were retrieved by a selective search in the PubMed database.

RESULTS

Intramedullary tumors often cause diffuse neurologic symptoms of gradually increasing severity, progressing, in advanced cases, to a complete spinal cord transection syndrome. Magnetic resonance imaging of the spine without and with intravenous contrast is the standard diagnostic technique. The histopathological origin of most intramedullary tumors is from glial cells, but other types of intramedullary tumor exist as well. The primary treatment of all intramedullary tumors is surgical resection. 9% to 34% of patients may experience a worse neurological deficit after surgery than before, but such problems resolve completely in 25% to 41% of cases. The extent of resection is the main factor affecting the risk of tumor recurrence and progression. The extent of resection also determines the possible indication for adjuvant treatment, which is needed, in particular, for high-grade and subtotally resected tumors, and for those that display progression. The treatment of intramedullary tumors is based on case series, retrospective analyses, and case reports, as randomized trials are lacking.

CONCLUSION

Patients with intramedullary tumors should be cared for, as much as possible, in the setting of prospective, uniform studies of their spontaneous course and the outcomes after treatment. This will yield better evidence on the treatment of these tumors in the future.

Determining the Predictors of Recurrence or Regrowth Following Spinal Astrocytoma Resection: A Systematic Review and Meta-Analysis

BACKGROUND/OBJECTIVES

Spinal astrocytomas (SA) represent 30-40% of all intramedullary spinal cord tumors (IMSCTs) and present significant clinical challenges due to their aggressive behavior and potential for recurrence. We aimed to pool the evidence on SA and investigate predictors of regrowth or recurrence after surgical resection.

METHODS

A systematic review and meta-analysis were conducted on peer-reviewed human studies from several databases covering the field of SA. Data were collected including sex, age, tumor location, extent of resection, histopathological diagnosis, and adjuvant therapy to identify predictors of SA recurrence. Recurrence was defined as failure of local tumor control or regrowth after treatment.

RESULTS

A total of 53 studies with 1365 patients were included in the meta-analysis. A postoperative deterioration in neurological outcomes, as assessed by the modified McCormick scale, was noted in most of the patients. The overall recurrence rate amounted to 41%. On meta-analysis, high-grade WHO tumors were associated with higher odds of recurrence (OR = 2.65; 95% CI: 1.87, 3.76; p = 0.001). Similarly, GTR was associated with lower odds of recurrence compared to STR (OR = 0.33; 95% CI: 0.18, 0.60; p = 0.0003). Sex (p = 0.5848) and tumor location (p = 0.3693) did not show any significant differences in the odds of recurrence. Intraoperative neurophysiological monitoring was described in 8 studies and adjuvant radiotherapy in 41 studies.

CONCLUSIONS

The results highlight the significant importance of tumor grade and extent of resection in patient prognosis. The role of adjuvant radiotherapy remains unclear, with most studies suggesting no differences in outcomes, with limitations due to potential confounders.

Astrocytomas of the spinal cord

Tumors of astrocytic origin represent one of the most frequent entities among the overall rare group of spinal cord gliomas. Initial clinical symptoms are often unspecific, and sensorimotor signs localizing to the spinal cord occur with progressing tumor growth. On MRI, a hyperintense intrinsic spinal cord signal on T2-weighted sequences with varying degrees of contrast enhancement raises suspicion for an infiltrative neoplasm. Blood and CSF analysis serves to exclude an infectious process, nutritional deficits, or metabolic disorders. When such other differential diagnoses have been ruled out, a neuropathological tissue-based analysis is warranted to confirm the diagnosis of a spinal cord astrocytoma and guide further patient management. As such, maximal safe resection forms the basis of any treatment. Meticulous preoperative planning is necessary to weigh the potential improvement in survival against the risk of functional deterioration. Intraoperative neuromonitoring and ultrasound may aid in achieving a more extensive resection. Depending on the assigned WHO tumor grade spanning from grade 1 to grade 4, the use of radiotherapy and chemotherapy might be indicated but also wait-and-scan approaches appear reasonable in tumors of lower grade. Close imaging follow-up is necessary given that recurrence inevitably occurs in astrocytomas of grades 2-4. Prognosis is so far dictated by tumor grade and histopathological findings, but also by age and clinical performance of the patient. Targeted therapies resting upon an in-depth tissue analysis are emerging in recurrent tumors, but no prospective study is available so far given the rarity of spinal cord astrocytomas.

The disparity in pediatric spinal cord tumor clinical trials: A scoping review of registered clinical trials from 1989 to 2023

Background

Spinal cord tumors (SCTs) comprise 10% of all central nervous system (CNS) tumors. Pediatric SCTs are often excluded and underrepresented in clinical trials though exclusion rates haven't been reported.

Methods

We reviewed all interventional clinical trials recruiting patients <21 years with SCTs on ClinicalTrials.gov between 1989 and 2023.

Results

Five hundred and two CNS tumor trials were identified, of which 255 included SCTs and/or spincal metastases. Among these, 96.5% were open to all CNS tumors (brain or spine); however, only 3.5% were exclusive to spine tumors. One trial was specific to pediatric spine tumors (inclusive of bone, soft tissue, and neural tumors); no trial was specific to primary pediatric SCTs. Most trials were located in North America, with multisite investigations being more common than single-institution designs. Trials frequently evaluated interventions/treatments (89%), supportive care/quality of life measures (7.1%), or diagnostic protocols (3.1%). Among included treatment paradigms, systemic therapies using cytotoxic chemotherapies, targeted therapies, and/or immunotherapies were more common among brain/spine trials, while radiotherapy, surgical adjuncts, and/or local drug delivery more frequently occurred in spinal tumor trials.

Conclusions

Though SCTs comprise 10% of pediatric CNS tumors, they remain underrepresented in clinical trials. This lack of trials specific to advancing pediatric SCTs management highlights an area of clinical and research need.

Intramedullary pediatric low-grade glioma of the spine

PURPOSE

Pediatric intramedullary spinal cord low-grade gliomas (pLGGs) are rare diagnoses among central nervous system (CNS) tumors in the pediatric population. The classic presentation of the patients includes some degree of neurologic deficit, although many times the symptoms are vague which leads to delayed diagnosis.

MATERIAL AND METHODS

The first step in the diagnosis includes special parameters in spinal imaging, particularly magnetic resonance imaging (MRI), and surgical resection remains the cornerstone for both diagnosis and treatment. Yet, recent years advancement in molecular and genetic understanding of CNS tumors allows for better adjustment of the treatment and follow-up regimens. Based on postoperative status, adjuvant therapy may provide additional therapeutic advantage for some types of tumors.

CONCLUSION

Ultimately, patients have a very promising prognosis when treated appropriately in most of the cases of pediatric spinal cord LGG with continued advances arising. This manuscript summarizes the most contemporary evidence regarding clinical and treatment features of intramedullary pLGGs.

Development and internal validation of machine learning models for personalized survival predictions in spinal cord glioma patients

BACKGROUND CONTEXT

Numerous factors have been associated with the survival outcomes in patients with spinal cord gliomas (SCG). Recognizing these specific determinants is crucial, yet it is also vital to establish a reliable and precise prognostic model for estimating individual survival outcomes.

OBJECTIVE

The objectives of this study are twofold: first, to create an array of interpretable machine learning (ML) models developed for predicting survival outcomes among SCG patients; and second, to integrate these models into an easily navigable online calculator to showcase their prospective clinical applicability.

STUDY DESIGN

This was a retrospective, population-based cohort study aiming to predict the outcomes of interest, which were binary categorical variables, in SCG patients with ML models.

PATIENT SAMPLE

The National Cancer Database (NCDB) was utilized to identify adults aged 18 years or older who were diagnosed with histologically confirmed SCGs between 2010 and 2019.

OUTCOME MEASURES

The outcomes of interest were survival outcomes at three specific time points postdiagnosis: 1, 3, and 5 years. These outcomes were formed by combining the "Vital Status" and "Last Contact or Death (Months from Diagnosis)" variables. Model performance was evaluated visually and numerically. The visual evaluation utilized receiver operating characteristic (ROC) curves, precision-recall curves (PRCs), and calibration curves. The numerical evaluation involved metrics such as sensitivity, specificity, accuracy, area under the PRC (AUPRC), area under the ROC curve (AUROC), and Brier Score.

METHODS

We employed five ML algorithms-TabPFN, CatBoost, XGBoost, LightGBM, and Random Forest-along with the Optuna library for hyperparameter optimization. The models that yielded the highest AUROC values were chosen for integration into the online calculator. To enhance the explicability of our models, we utilized SHapley Additive exPlanations (SHAP) for assessing the relative significance of predictor variables and incorporated partial dependence plots (PDPs) to delineate the influence of singular variables on the predictions made by the top performing models.

RESULTS

For the 1-year survival analysis, 4,913 patients [5.6% with 1-year mortality]; for the 3-year survival analysis, 4,027 patients (11.5% with 3-year mortality]; and for the 5-year survival analysis, 2,854 patients (20.4% with 5-year mortality) were included. The top models achieved AUROCs of 0.938 for 1-year mortality (TabPFN), 0.907 for 3-year mortality (LightGBM), and 0.902 for 5-year mortality (Random Forest). Global SHAP analyses across survival outcomes at different time points identified histology, tumor grade, age, surgery, radiotherapy, and tumor size as the most significant predictor variables for the top-performing models.

CONCLUSIONS

This study demonstrates ML techniques can develop highly accurate prognostic models for SCG patients with excellent discriminatory ability. The interactive online calculator provides a tool for assessment by physicians (https://huggingface.co/spaces/MSHS-Neurosurgery-Research/NCDB-SCG). Local interpretability informs prediction influences for a given individual. External validation across diverse datasets could further substantiate potential utility and generalizability. This robust, interpretable methodology aligns with the goals of precision medicine, establishing a foundation for continued research leveraging ML's predictive power to enhance patient counseling.

What Factors Predict the Development of Neurologic Deficits Following Resection of Intramedullary Spinal Cord Tumors: A Multi-Center Study

BACKGROUND

Intramedullary spinal cord tumors are challenging to resect, and their postoperative neurological outcomes are often difficult to predict, with few studies assessing this outcome.

METHODS

We reviewed the medical records of all patients surgically treated for Intramedullary spinal cord tumors at our multisite tertiary care institution (Mayo Clinic Arizona, Mayo Clinic Florida, Mayo Clinic Rochester) between June 2002 and May 2020. Variables that were significant in the univariate analyses were included in a multivariate logistic regression. "MissForest" operating on the Random Forest algorithm, was used for data imputation, and K-prototype was used for data clustering. Heatmaps were added to show correlations between postoperative neurological deficit and all other included variables. Shapley Additive exPlanations were implemented to understand each feature's importance.

RESULTS

Our query resulted in 315 patients, with 160 meeting the inclusion criteria. There were 53 patients with astrocytoma, 66 with ependymoma, and 41 with hemangioblastoma. The mean age (standard deviation) was 42.3 (17.5), and 48.1% of patients were women (n = 77/160). Multivariate analysis revealed that pathologic grade >3 (OR = 1.55; CI = [0.67, 3.58], P = 0.046 predicted a new neurological deficit. Random Forest algorithm (supervised machine learning) found age, use of neuromonitoring, histology of the tumor, performing a midline myelotomy, and tumor location to be the most important predictors of new postoperative neurological deficits.

CONCLUSIONS

Tumor grade/histology, age, use of neuromonitoring, and myelotomy type appeared to be most predictive of postoperative neurological deficits. These results can be used to better inform patients of perioperative risk.

Neurological Outcome and Respiratory Insufficiency in Intramedullary Tumors of the Upper Cervical Spine

Background and Objectives: Intramedullary spinal cord tumors (IMSCT) are rare entities. A location in the upper cervical spine as a highly eloquent region carries the risk of postoperative neurological deficits, such as tetraparesis or respiratory dysfunction. Evidence for respiratory dysfunction is scarce. This study aimed to describe these highly eloquent tumors' early and late postoperative clinical course. Materials and Methods: This is a single-center retrospective cohort study. We included 35 patients with IMSCT at levels of the craniocervical junction to C4 who underwent surgical treatment between 2008 and 2022. The authors analyzed the patients' preoperative status, tumor- and surgery-specific characteristics, and follow-up functional status. Results: The study cohort included twenty-two patients with grade II ependymoma (62.9%), two low-grade astrocytomas (5.7%), two glioblastomas (5.7%), six hemangioblastomas (17.1%), two metastases (5.7%), and one patient with partially intramedullary schwannoma (2.9%). Gross total resection was achieved in 76% of patients. Early dorsal column-related symptoms (gait ataxia and sensory loss) and motor deterioration occurred in 64% and 44% of patients. At a follow-up of 3.27 ± 3.83 years, 43% and 33% of patients still exhibited postoperative sensory and motor deterioration, respectively. The median McCormick Scale grade was 2 in the preoperative and late postoperative periods, respectively. Only three patients (8.6%) developed respiratory dysfunction, of whom, two patients, both with malignant IMSCT, required prolonged invasive ventilation. Conclusions: More than 60% of the patients with IMSCT in the upper cervical cord developed new neurological deficits in the immediate postoperative period, and more than 40% are permanent. However, these deficits are not disabling in most cases since most patients maintain functional independence as observed by unchanged low McCormick scores. The rate of respiratory insufficiency is relatively low and seems to be influenced by the rapid neurological deterioration in high-grade tumors.

Approaches to Incidental Intradural Tumors of the Spine in the Pediatric Population

BACKGROUND

Incidental intradural tumors of the spine in the pediatric population are rare lesions whose management remains unclear. Surgeons must balance the risks of iatrogenic deficits and complications after surgical resection against the risks from progressive growth of the tumor. Moreover, the natural history of an incidental finding can be difficult to predict. Here, we review the literature on incidental intradural tumors of the spine and present considerations for their management.

SUMMARY

Growth of the tumor or changes in radiographic features are usually indications for resection. Asymptomatic lesions can be found in patients with genetic syndromes that predispose to tumor formation, such as neurofibromatosis type 1 and 2, schwannomatosis, and Von-Hippel-Lindau syndrome, and careful workup of a genetic cause is warranted in any patient presenting with multiple tumors and/or cutaneous features. Close follow-up is generally favored given the heavy tumor burden; however, some recommend pre-emptive resection to prevent permanent neurological deficits. Incidental intradural tumors can also occur in association with hydrocephalus, significant syringomyelia, and cord compression, and surgical treatment is usually warranted. Tumors may also be discovered as part of the workup for scoliosis, where they are not truly incidental to the scoliosis but rather are contributing to curve deformation.

KEY MESSAGES

Thorough workup of patients for associated genetic syndromes or comorbidities should be undertaken in pediatric patients with incidental intradural tumors. Further research is needed into the natural history of these incidental lesions. Incidental tumors can often be managed conservatively with close follow-up, with surgical intervention warranted for expanding tumors or new-onset symptoms.

Applications of Focused Ultrasound for the Treatment of Glioblastoma: A New Frontier

Glioblastoma (GBM) is an aggressive primary astrocytoma associated with short overall survival. Treatment for GBM primarily consists of maximal safe surgical resection, radiation therapy, and chemotherapy using temozolomide. Nonetheless, recurrence and tumor progression is the norm, driven by tumor stem cell activity and a high mutational burden. Focused ultrasound (FUS) has shown promising results in preclinical and clinical trials for treatment of GBM and has received regulatory approval for the treatment of other neoplasms. Here, we review the range of applications for FUS in the treatment of GBM, which depend on parameters, including frequency, power, pulse duration, and duty cycle. Low-intensity FUS can be used to transiently open the blood-brain barrier (BBB), which restricts diffusion of most macromolecules and therapeutic agents into the brain. Under guidance from magnetic resonance imaging, the BBB can be targeted in a precise location to permit diffusion of molecules only at the vicinity of the tumor, preventing side effects to healthy tissue. BBB opening can also be used to improve detection of cell-free tumor DNA with liquid biopsies, allowing non-invasive diagnosis and identification of molecular mutations. High-intensity FUS can cause tumor ablation via a hyperthermic effect. Additionally, FUS can stimulate immunological attack of tumor cells, can activate sonosensitizers to exert cytotoxic effects on tumor tissue, and can sensitize tumors to radiation therapy. Finally, another mechanism under investigation, known as histotripsy, produces tumor ablation via acoustic cavitation rather than thermal effects.

Surgical approaches to intramedullary spinal cord astrocytomas in the age of genomics

Intramedullary astrocytomas represent approximately 30%–40% of all intramedullary tumors and are the most common intramedullary tumor in children. Surgical resection is considered the mainstay of treatment in symptomatic patients with neurological deficits. Gross total resection (GTR) can be difficult to achieve as astrocytomas frequently present as diffuse lesions that infiltrate the cord. Therefore, GTR carries a substantial risk of new post-operative deficits. Consequently, subtotal resection and biopsy are often the only surgical options attempted. A midline or paramedian sulcal myelotomy is frequently used for surgical resection, although a dorsal root entry zone myelotomy can be used for lateral tumors. Intra-operative neuromonitoring using D-wave integrity, somatosensory, and motor evoked potentials is critical to facilitating a safe resection. Adjuvant radiation and chemotherapy, such as temozolomide, are often administered for high-grade recurrent or progressive lesions; however, consensus is lacking on their efficacy. Biopsied tumors can be analyzed for molecular markers that inform clinicians about the tumor’s prognosis and response to conventional as well as targeted therapeutic treatments. Stratification of intramedullary tumors is increasingly based on molecular features and mutational status. The landscape of genetic and epigenetic mutations in intramedullary astrocytomas is not equivalent to their intracranial counterparts, with important difference in frequency and type of mutations. Therefore, dedicated attention is needed to cohorts of patients with intramedullary tumors. Targeted therapeutic agents can be designed and administered to patients based on their mutational status, which may be used in coordination with traditional surgical resection to improve overall survival and functional status.

Molecular Pathways and Genomic Landscape of Glioblastoma Stem Cells: Opportunities for Targeted Therapy

Glioblastoma (GBM) is an aggressive tumor of the central nervous system categorized by the World Health Organization as a Grade 4 astrocytoma. Despite treatment with surgical resection, adjuvant chemotherapy, and radiation therapy, outcomes remain poor, with a median survival of only 14-16 months. Although tumor regression is often observed initially after treatment, long-term recurrence or progression invariably occurs. Tumor growth, invasion, and recurrence is mediated by a unique population of glioblastoma stem cells (GSCs). Their high mutation rate and dysregulated transcriptional landscape augment their resistance to conventional chemotherapy and radiation therapy, explaining the poor outcomes observed in patients. Consequently, GSCs have emerged as targets of interest in new treatment paradigms. Here, we review the unique properties of GSCs, including their interactions with the hypoxic microenvironment that drives their proliferation. We discuss vital signaling pathways in GSCs that mediate stemness, self-renewal, proliferation, and invasion, including the Notch, epidermal growth factor receptor, phosphatidylinositol 3-kinase/Akt, sonic hedgehog, transforming growth factor beta, Wnt, signal transducer and activator of transcription 3, and inhibitors of differentiation pathways. We also review epigenomic changes in GSCs that influence their transcriptional state, including DNA methylation, histone methylation and acetylation, and miRNA expression. The constituent molecular components of the signaling pathways and epigenomic regulators represent potential sites for targeted therapy, and representative examples of inhibitory molecules and pharmaceuticals are discussed. Continued investigation into the molecular pathways of GSCs and candidate therapeutics is needed to discover new effective treatments for GBM and improve survival.