The results of radiotherapy for brainstem tumors

The Current State of Radiotherapy for Pediatric Brain Tumors: An Overview of Post-Radiotherapy Neurocognitive Decline and Outcomes

Tumors of the central nervous system are the most common solid malignancies diagnosed in children. While common, they are also found to have some of the lowest survival rates of all malignancies. Treatment of childhood brain tumors often consists of operative gross total resection with adjuvant chemotherapy or radiotherapy. The current body of literature is largely inconclusive regarding the overall benefit of adjuvant chemo- or radiotherapy. However, it is known that both are associated with conditions that lower the quality of life in children who undergo those treatments. Chemotherapy is often associated with nausea, emesis, significant fatigue, immunosuppression, and alopecia. While radiotherapy can be effective for achieving local control, it is associated with late effects such as endocrine dysfunction, secondary malignancy, and neurocognitive decline. Advancements in radiotherapy grant both an increase in lifetime survival and an increased lifetime for survivors to contend with these late effects. In this review, the authors examined all the published literature, analyzing the results of clinical trials, case series, and technical notes on patients undergoing radiotherapy for the treatment of tumors of the central nervous system with a focus on neurocognitive decline and survival outcomes.

Single institution experience in re-irradiation of biopsy-proven diffuse intrinsic pontine gliomas

OBJECTIVES

Diffuse intrinsic pontine glioma (DIPG) is the leading cause of death from CNS tumors in children. Multiple clinical trials have failed to show any benefit from systemic therapy in DIPG, and radiation therapy (RT) alone remains the standard of care. Re-irradiation (rRT) for symptomatic relief is an option at disease progression. However, published data on treatment details and outcomes are limited. The objective of this study was to review and report our institutional experience with re-irradiation of patients with biopsy-proven DIPG.

METHODS

We identified a cohort of pediatric patients with biopsy-proven DIPG with clinical disease progression after initial radiotherapy who received a second course of radiotherapy at our institution. We reviewed patient and treatment characteristics and outcomes.

RESULTS

Between January 2014 and July 2018, we identified five patients with progressive DIPG who received re-irradiation. Re-irradiation was well tolerated with no serious adverse events reported and all patients experiencing stable to improved neurologic function during treatment. Median survival from completion of re-irradiation was 116 days (range 62 to 159 days). Median overall survival from time of diagnosis was 16.3 months (range 13.0 to 18.0 months), which is longer than the historical average of less than 12 months. In patients with available postmortem neuropathology, common findings were Wallerian degeneration and necrosis.

CONCLUSIONS

In our experience, re-irradiation is safe and feasible for patients with DIPG with symptomatic disease progression following initial radiotherapy treatment.

5-aminolevulinic acid-guided surgery for focal pediatric brainstem gliomas: A preliminary study

Background:

There is a growing body of literature supporting the use of 5-aminolevulinic acid (5-ALA) in the pediatric population, however, its use is still considered “off label” in this setting. In this retrospective study, we report our experience using 5-ALA in pediatric patients with focal brainstem gliomas (BSGs).

Methods:

Patients younger than 16 years presenting with a newly diagnosed BSG that was focal in nature were considered suitable for treatment with 5-ALA-assisted surgery. Exclusion criteria included MRI features suggestive of a diffuse intrinsic pontine glioma. A single dose of 5-ALA was administered preoperatively. Intraoperative fluorescence was recorded as “solid,” “vague,” or “none.” The effectiveness of the fluorescence was graded as “helpful” or “unhelpful.”

Results:

Eight patients underwent 5-ALA-assisted surgery. There were four tumors located in the pons, two midbrain tumors, and two cervicomedullary tumors. Histological analysis demonstrated three diffuse astrocytomas, three pilocytic astrocytomas, and two anaplastic astrocytomas. Solid fluorescence was found in three of the eight cases, vague fluorescence was found in two cases, and no fluorescence was found in three cases. Fluorescence was useful in 3 (37%) cases. No patients experienced any complications attributable to the administration of the 5-ALA.

Conclusion:

With a total fluorescence rate of 62.5% but a subjectively assessed “usefulness” rate of only 37.5%, the role of 5-ALA in BSG surgery is limited. Given the toxicological safety, however, of the agent, caution is perhaps needed before dismissing the use of 5-ALA entirely.

CRISPRi-based radiation modifier screen identifies long non-coding RNA therapeutic targets in glioma

BACKGROUND

Long non-coding RNAs (lncRNAs) exhibit highly cell type-specific expression and function, making this class of transcript attractive for targeted cancer therapy. However, the vast majority of lncRNAs have not been tested as potential therapeutic targets, particularly in the context of currently used cancer treatments. Malignant glioma is rapidly fatal, and ionizing radiation is part of the current standard-of-care used to slow tumor growth in both adult and pediatric patients.

RESULTS

We use CRISPR interference (CRISPRi) to screen 5689 lncRNA loci in human glioblastoma (GBM) cells, identifying 467 hits that modify cell growth in the presence of clinically relevant doses of fractionated radiation. Thirty-three of these lncRNA hits sensitize cells to radiation, and based on their expression in adult and pediatric gliomas, nine of these hits are prioritized as lncRNA Glioma Radiation Sensitizers (lncGRS). Knockdown of lncGRS-1, a primate-conserved, nuclear-enriched lncRNA, inhibits the growth and proliferation of primary adult and pediatric glioma cells, but not the viability of normal brain cells. Using human brain organoids comprised of mature neural cell types as a three-dimensional tissue substrate to model the invasive growth of glioma, we find that antisense oligonucleotides targeting lncGRS-1 selectively decrease tumor growth and sensitize glioma cells to radiation therapy.

CONCLUSIONS

These studies identify lncGRS-1 as a glioma-specific therapeutic target and establish a generalizable approach to rapidly identify novel therapeutic targets in the vast non-coding genome to enhance radiation therapy.

Brainstem Low-Grade Gliomas in Children-Excellent Outcomes With Multimodality Therapy

Safe maximal surgical resection is the initial treatment of choice for pediatric brainstem low-grade gliomas. Optimal therapy for incompletely resected tumors or that progress after surgery is uncertain. We reviewed the clinical characteristics, therapy, and outcomes of all children with nontectal brainstem low-grade gliomas treated at the University of Michigan between 1993 and 2013. Median age at diagnosis was 6 years; histology was confirmed in 23 of 25 tumors, 64% were pilocytic astrocytoma. Nineteen patients underwent initial tumor resection; 14/19 received no upfront adjuvant therapy. Eight patients in the study had progressive disease; 5 initially resected tumors received chemotherapy at tumor relapse, all with partial or complete radiographic responses. Ten-year progression-free survival is 71% and overall survival, 100%. This single-institution retrospective study demonstrates excellent survival rates for children with brainstem low-grade gliomas. The efficacy of the well-tolerated chemotherapy in this series supports its role in the treatment of unresectable or progressive brainstem low-grade gliomas.

Principles of radiation therapy

Although resection remains the mainstay in the treatment of gliomas, microscopically complete resection of most central nervous system tumors remains challenging, and is, in fact, rarely accomplished. Considering their invasive nature, gross total resections to clearly negative margins often do or would require removal or transection of functional brain, with likely serious neurologic deficits. Consequently, radiotherapy has emerged as an indispensable component of therapy. It is delivered primarily by external-beam radiotherapy or brachytherapy techniques. Herein, we present the biologic principles, techniques, and applications of radiotherapy in glioma treatment today.

Analysis of survival in pediatric high-grade brainstem gliomas: A population-based study

Background:

The purpose of this study was to use the National Cancer Institutes’ Surveillance, Epidemiology, and End Results (SEER) database to perform a large-scale analysis of brainstem anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM). Use of the SEER database gave us a larger sample size of this rare tumor type, allowing for the analysis of the relationship between prognostic factors and survival.

Materials and Methods:

We selected pediatric patients (<18 years old) from the SEER database with histologically confirmed diagnoses of primary high-grade gliomas (World Health Organization Grade III/IV) of the brainstem. In univariate and multivariate analysis, we analyzed the relationship between demographic (age, gender, race, diagnosis date), histologic (AA, GBM), and treatment (surgery, radiation) factors on survival.

Results:

In our cohort of 124 patients, those with AA had a median survival of 13 months and those with GBM 9 months. Higher-grade tumors were associated with statistically significantly increased mortality (hazard ratio [HR]: 1.74, confidence intervals [CIs]: 1.17-2.60). Surgical intervention was associated with a significantly lower mortality, either alone (HR: 0.14, CI: 0.04-0.5) or in combination with radiation (HR: 0.35, CI: 0.15-0.82). Radiation therapy alone was significantly associated with decreased mortality within the first 9 months after diagnosis but not with overall mortality. No demographic characteristics were significantly associated with mortality.

Conclusions:

Outcome remains poor in the pediatric high-grade brainstem glioma population. Survival is correlated with lower-grade tumor histology, radiation therapy only in the first 9 months after diagnosis, and surgical resection.

A twenty-year review of diagnosing and treating children with diffuse intrinsic pontine glioma in The Netherlands

INTRODUCTION

Children with diffuse intrinsic pontine glioma (DIPG) face a dismal prognosis, with a median overall survival of 9 months. Our aims are to determine the incidence of DIPG in the Netherlands and to identify points for improvement in clinical research, a prerequisite for increasing the chance to find a cure.

METHODS

We performed a population-based retrospective cohort study by evaluating all children diagnosed with DIPG in the Netherlands between 1990 and 2010.

RESULTS

The incidence of DIPG in the Netherlands corresponds with international literature. Between 1990 and 2010, a large heterogeneity of treatment schedules was applied and only a minority of patients was included in clinical trials.

DISCUSSION

Given the rarity of DIPG, we emphasize the need for (inter-)national trials to facilitate the identification of potentially effective therapeutics in the future. This can be supported by the recent development of a European DIPG registry enabling international study collaborations.

Clinical management and outcome of histologically verified adult brainstem gliomas in Switzerland: a retrospective analysis of 21 patients

Because of low incidence, mixed study populations and paucity of clinical and histological data, the management of adult brainstem gliomas (BSGs) remains non-standardized. We here describe characteristics, treatment and outcome of patients with exclusively histologically confirmed adult BSGs. A retrospective chart review of adults (age >18 years) was conducted. BSG was defined as a glial tumor located in the midbrain, pons or medulla. Characteristics, management and outcome were analyzed. Twenty one patients (17 males; median age 41 years) were diagnosed between 2004 and 2012 by biopsy (n = 15), partial (n = 4) or complete resection (n = 2). Diagnoses were glioblastoma (WHO grade IV, n = 6), anaplastic astrocytoma (WHO grade III, n = 7), diffuse astrocytoma (WHO grade II, n = 6) and pilocytic astrocytoma (WHO grade I, n = 2). Diffuse gliomas were mainly located in the pons and frequently showed MRI contrast enhancement. Endophytic growth was common (16 vs. 5). Postoperative therapy in low-grade (WHO grade I/II) and high-grade gliomas (WHO grade III/IV) consisted of radiotherapy alone (three in each group), radiochemotherapy (2 vs. 6), chemotherapy alone (0 vs. 2) or no postoperative therapy (3 vs. 1). Median PFS (24.1 vs. 5.8 months; log-rank, p = 0.009) and mOS (30.5 vs. 11.5 months; log-rank, p = 0.028) was significantly better in WHO grade II than in WHO grade III/IV tumors. Second-line therapy considerably varied. Histologically verification of adult BSGs is feasible and has an impact on postoperative treatment. Low-grade gliomas can simple be followed or treated with radiotherapy alone. Radiochemotherapy with temozolomide can safely be prescribed for high-grade gliomas without additional CNS toxicities.

Management and outcome of focal low-grade brainstem tumors in pediatric patients: the St. Jude experience

OBJECT

Whereas diffuse intrinsic pontine gliomas generally have a short symptom duration and more cranial nerve involvement, focal brainstem gliomas are commonly low grade, with fewer cranial neuropathies. Although these phenotypic distinctions are not absolute predictors of outcome, they do demonstrate correlation in most cases. Because there is a limited literature on focal brainstem gliomas in pediatric patients, the objective of this paper was to report the management and outcome of these tumors.

METHODS

The authors reviewed the records of all children diagnosed with radiographically confirmed low-grade focal brainstem gliomas from 1986 to 2010. Each patient underwent biopsy or resection for tissue diagnosis. Event-free survival (EFS) and overall survival were evaluated. Univariate analysis was conducted to identify demographic and treatment variables that may affect EFS.

RESULTS

Fifty-two patients (20 girls, 32 boys) with follow-up data were identified. Median follow-up was 10.0 years, and the median age at diagnosis was 6.5 years (range 1-17 years). The tumor locations were midbrain (n = 22, 42%), pons (n = 15, 29%), and medulla (n = 15, 29%). Surgical extirpation was the primary treatment in 25 patients (48%). The 5- and 10-year EFS and overall survival were 59%/98% and 52%/90%, respectively. An event or treatment failure occurred in 24 patients (46%), including 5 deaths. Median time to treatment failure was 3.4 years. Disease progression in the other 19 patients transpired within 25.1 months of diagnosis. Thirteen of these patients received radiation, including 11 within 2 months of primary treatment failure. Although children with intrinsic tumors had slightly better EFS at 5 years compared with those with exophytic tumors (p = 0.054), this difference was not significant at 10 years (p = 0.147). No other variables were predictive of EFS.

CONCLUSIONS

Surgery suffices in many children with low-grade focal brainstem gliomas. Radiation treatment is often reserved for disease progression but offers comparable disease control following biopsy. In the authors' experience, combining an assessment of clinical course, imaging, and tumor biopsy yields a reasonable model for managing children with focal brainstem tumors.

Balloon-assisted superselective intra-arterial cerebral infusion of bevacizumab for malignant brainstem glioma. A technical note

Malignant brainstem gliomas (BSG) are rare tumors in adults, associated with a grim prognosis and limited treatment options. Currently, radiotherapy represents the mainstay of treatment, although new studies suggest an increased role for certain chemotherapeutic agents. Intravenous (IV) administration of bevacizumab (Avastin, Genentech Pharmaceuticals) has been shown to be active in the treatment of some enhancing malignant brainstem gliomas. The IV route of administration, however, carries a risk of systemic side effects such as bowel perforation, wound disrepair and pulmonary embolism. In addition, the percentage of IV drug that reaches the tumor site is restricted by the blood brain barrier (BBB).Weill Cornell Brain Tumor Center, Department of Neurosurgery, Weill Cornell Medical College of Cornell University: New York, NY, USA. This technical report describes our protocol in performing superselective intra-arterial cerebral infusion (SIACI) of bevacizumab using endovascular balloon-assistance in the top of the basilar artery in a patient with a recurrent malignant brainstem glioma. It represents the first time such a technique has been performed for this disease. This method of drug delivery may have important implications in the treatment of both adult and pediatric brainstem gliomas.

Osmotic blood–brain barrier disruption chemotherapy for diffuse pontine gliomas

The prognosis for patients with diffuse pontine gliomas (DPG) remains poor. New aggressive innovative treatments are necessary to treat this disease. From 1984 to 1998, eight patients (4M/4F), median age 11 years, with DPG were treated with monthly osmotic blood-brain barrier disruption (BBBD) chemotherapy using intraarterial carboplatin or methotrexate and intravenous cytoxan and etoposide. Patients presented for a median duration of 6 weeks with increased intracranial pressure, long tract signs, diplopia, ataxia, and nausea/vomiting. DPG was demonstrated on magnetic resonance (MR) imaging in seven patients and on CT in one. Two patients had biopsies that showed an astrocytoma and an anaplastic astrocytoma. Three tumors enhanced on MR imaging after contrast administration. Three patients had radiation therapy before BBBD chemotherapy and four afterwards. Two patients had chemotherapy (tamoxifen, topotecan) before BBBD chemotherapy and two afterwards. In general, patients were evaluated with MR imaging every 3 months to monitor for a response to treatment. The median number of chemotherapy cycles that were administered by BBBD was 10, mean 10. Three patients also received one, two, or three cycles of intraarterial chemotherapy without BBBD. One patient that was started on carboplatin was converted to methotrexate, and five that were started on the methotrexate protocol were later converted over to carboplatin. One patient received monthly methotrexate followed by 14 days of procarbazine and one patient started on methotrexate was switched to navelbine. MR imaging demonstrated two partial responses, five patients with stable disease, and one with disease progression. The median time to tumor progression was 15 months with the range from <1 to 40 months. The median survival from the time of diagnosis was 27 months, ranging from 7 to 80 months. The median survival time from the first BBBD or intraarterial treatment was 16.5 months, ranging from 5 to 69 months. One patient was lost to follow-up with an unknown date of death. Although the sample size is small, the TTP and survival times are longer than those previously reported in other DPG series. In addition, the ability to demonstrate stable disease or partial responses in DPG on MR imaging argues for the therapeutic benefit of BBBD chemotherapy. The enhanced delivery of chemotherapy afforded by osmotic BBBD supports the further examination of this treatment modality for patients with DPG.

Biopsy of brain stem glioma using motor-evoked potential mapping by direct peduncular stimulation and individual adjuvant therapy. Case report

A 23-year-old man presented with a brain stem glioma manifesting as a 6-month history of right hemiparesis and diplopia. Serial magnetic resonance imaging showed an intrinsic diffuse brain stem glioma that gradually localized to the left cerebral peduncle after initial adjuvant therapy. Surgery was performed through a left subtemporal transtentorial approach under motor-evoked potential (MEP) mapping by direct peduncular stimulation. The lateral aspect of the midbrain was exposed, a train of five bipolar 25 mA pulses was applied, and MEPs recorded from the extremities. MEPs were only recorded from the left extremities even with left cerebral peduncular stimulation. Partial resection of the tumor was safely performed, with slight temporary neurological worsening. The histological diagnosis was anaplastic astrocytoma. Individual adjuvant therapy based on the results of real-time reverse transcription-polymerase chain reaction of O6-methylguanine-deoxyribonucleic acid methyltransferase achieved an almost complete tumor response. Surgery under pyramidal tract mapping and intensive postoperative adjuvant therapy resulted in a good outcome despite the presence of a generally intractable intrinsic brain stem glioma.

Surgical outcome following resection of contrast-enhanced pediatric brainstem gliomas

BACKGROUND

The role of surgery in the management of gadolinium-enhancing pediatric brainstem lesions on magnetic resonance imaging (MRI) has been a matter of open debate. This clinical series correlates radiological and pathological findings to assess the role of contrast enhancement as an indication for surgery with respect to clinical outcome.

METHODS

We retrospectively reviewed the charts of all pediatric patients admitted to the Johns Hopkins Hospital with a diagnosis of a brainstem tumor between January 1985 and December 2000.

RESULTS

There were a total of 89 patients who met the inclusion criteria. Fifty-seven patients (64.0%) underwent surgical resection while 32 (36%) were treated with radiation and/or chemotherapy. Of the surgical candidates, 57 (100%) had an accompanying MRI scan significant for an enhancing lesion in the midbrain, pons or the medulla. The pathology was consistent with juvenile pilocytic astrocytoma in 30 patients (52.6%) and glioblastoma multiforme in 12 patients (21.1%). The remaining cases consisted of 10 patients (17.5%) with fibrillary astrocytomas, 3 (5.3%) with gangliogliomas, 1 (1.8%) with an oligodendroglioma and 1 (1.8%) with a primitive neuroectodermal tumor. A total of 29 patients had a total surgical resection, 8 a near total resection (>90%), 15 a subtotal resection (50-90%) and 5 a partial resection (<50%). The progression-free survival of all patients was 71.9% at 3 years and 45.6% at 5 years.

CONCLUSIONS

This case series illustrates that contrast-enhanced MRI has positive prognostic value in the management of pediatric brainstem gliomas. In our study, the majority of enhancing tumors were low grade and amenable to surgical intervention. Consequently, we recommend surgical resection and pathological diagnosis of all enhancing brainstem tumors with adjuvant therapy reserved for recurrent or unresectable cases.

Experimental rodent models of brainstem tumors

Despite recent advances in surgical technology, resection is not an option for many brainstem tumors. Experimental models have played essential roles in examining new approaches to therapy. The objective of the present study was to generate models by determining coordinates for safe inoculation into the brainstem of mice and rats, and to establish whether the implantation of heterotopic cells would create reproducible survival curves. Morbidity and survival studies were used to map stereotactic coordinates allowing successful inoculation of tumor cells. Survival studies were used to investigate the time course of tumor growth. Tumor location was examined by light microscopy and magnetic resonance imaging. Mice survived injections of 2 microL of saline at interaural, lateral, and depth coordinates of -2.5, 1.0, and 3.5 mm and -1.5, 1.0, and 3.5 mm. Rats survived injections at interaural, lateral, and depth coordinates of -2.0, 2.0, and 7.0 mm and -3.0, 0, and 7.0 mm. Median survival of mice challenged with 5 x 10(5) EMT6 and 10(4) B16 tumor cells was 11 and 10 days, respectively. Median survival for rats challenged with 10(4) 9L and F98 cells was 14 and 13 days, respectively. The present study demonstrates a feasible approach to preparing models of brainstem tumors. Limitations of these models are discussed.