Proton therapy for low-grade gliomas in adults: A systematic review

Symptom experience and symptom distress in patients with malignant brain tumor treated with proton therapy: A five-year follow-up study

Background and purpose

Since patients with primary brain tumor are expected to become long-term survivors, the prevention of long-term treatment-induced side effects is particularly important. This study aimed to explore whether symptom experience and symptom distress change over five years in adults with primary brain tumors treated with proton therapy. An additional aim was to explore whether symptom experience and symptom distress correlate.

Materials and methods

The study had a longitudinal observational design. Adult (≥18 years) patients (n = 170) with primary brain tumors treated with proton therapy were followed over five years. Symptom experience and symptom distress were evaluated using the patient-reported Radiotherapy-Related Symptom Assessment Scale. Data from baseline, 1, 12, and 60 months were analyzed using non-parametric tests.

Results

Of the 170 patients, the levels of symptoms and symptom distress were low. Fatigue increased at 1 (p=0.005) and 12 months (p=0.025) and was the most frequent symptom from baseline to 60 months' follow-up. Cognitive impairment increased at 12 (p=0.027) and 60 months (p<0.001) and was the most distressing symptom at 60 months' follow-up. There were significant, moderate to strong, correlations at all time points between symptom experience and symptom distress of fatigue, insomnia, pain, dyspnea, cognitive impairment, worry, anxiety, nausea, sadness, constipation, and skin reactions.

Conclusion

Symptom experience and symptom distress changed in intensity over time with cognitive impairment as the most distressing symptom at 60 months. Future research should focus on identifying effective interventions aimed at alleviating these symptoms and reducing symptom distress for this vulnerable group of patients.

Dosimetric comparison of advanced radiation techniques for scalp-sparing in low-grade gliomas

BACKGROUND

Alopecia causes significant distress for patients and negatively impacts quality of life for low-grade glioma (LGG) patients. We aimed to compare and evaluate variations in dose distribution for scalp-sparing in LGG patients with proton therapy and photon therapy, namely intensity-modulated proton therapy (IMPT), intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), and helical tomotherapy (HT).

METHODS

This retrospective study utilized a dataset comprising imaging data from 22 patients with LGG who underwent postoperative radiotherapy. Treatment plans were generated for each patient with scalp-optimized (SO) approaches and scalp-non-optimized (SNO) approaches using proton techniques and photons techniques; all plans adhered to the same dose constraint of delivering a total radiation dose of 54.04 Gy to the target volume. All treatment plans were subsequently analyzed.

RESULTS

All the plans generated in this study met the dose constraints for the target volume and OARs. The SO plans resulted in reduced maximum scalp dose (Dmax), mean scalp dose (Dmean), and volume of the scalp receiving 30 Gy (V30) and 40 Gy (V40) compared with SNO plans in all radiation techniques. Among all radiation techniques, the IMPT plans exhibited superior performance compared to other plans for dose homogeneity as for SO plans. Also, IMPT showed lower values for Dmean and Dmax than all photon radiation techniques.

CONCLUSION

Our study provides evidence that the SO approach is a feasible technique for reducing scalp radiation dose. However, it is imperative to conduct prospective trials to assess the benefits associated with this approach.

Current state of proton therapy for tumors of the central nervous system in Spain: physical bases, indications, controversies and perspectives

The unique biophysical properties of proton therapy (PT), regarding the precise dose distribution, a remarkable better sparing of surrounding normal tissues, and the decreasing costs have promoted the spread of this technique worldwide. In Spain, eleven new PT centers, added to the currently two in function, are expected to be available in the near future. Indications for PT are currently evolving. The suitability of PT in central nervous system tumors of the adult population has been extrapolated from the favorable experience in children and adolescents. Given the lack of appropriate randomized trials, controversies remain regarding its use in lower grade tumors, re-irradiation, and other clinical scenarios in which an a priori dose distribution benefit is expected compared to photon-based radiotherapy. PT is a reasonable option in many brain and spinal tumors associating long life expectancy, in which cognitive decline, and the appearance of radiation-induced neoplasms can be minimized.Estado actual de la terapia con protones en los tumores del sistema nervioso central en España: bases físicas, indicaciones, controversias y perspectivas.

Low grade gliomas guide-lines elaborated by the tumor section of Spanish Society of Neurosurgery

Adult low-grade gliomas (Low Grade Gliomas, LGG) are tumors that originate from the glial cells of the brain and whose management involves great controversy, starting from the diagnosis, to the treatment and subsequent follow-up. For this reason, the Tumor Group of the Spanish Society of Neurosurgery (GT-SENEC) has held a consensus meeting, in which the most relevant neurosurgical issues have been discussed, reaching recommendations based on the best scientific evidence. In order to obtain the maximum benefit from these treatments, an individualised assessment of each patient should be made by a multidisciplinary team. Experts in each LGG treatment field have briefly described it based in their experience and the reviewed of the literature. Each area has been summarized and focused on the best published evidence. LGG have been surrounded by treatment controversy, although during the last years more accurate data has been published in order to reach treatment consensus. Neurosurgeons must know treatment options, indications and risks to participate actively in the decision making and to offer the best surgical treatment in every case.

An In Vitro Model of Glioma Development

Gliomas are the prevalent forms of brain cancer and derive from glial cells. Among them, astrocytomas are the most frequent. Astrocytes are fundamental for most brain functions, as they contribute to neuronal metabolism and neurotransmission. When they acquire cancer properties, their functions are altered, and, in addition, they start invading the brain parenchyma. Thus, a better knowledge of transformed astrocyte molecular properties is essential. With this aim, we previously developed rat astrocyte clones with increasing cancer properties. In this study, we used proteomic analysis to compare the most transformed clone (A-FC6) with normal primary astrocytes. We found that 154 proteins are downregulated and 101 upregulated in the clone. Moreover, 46 proteins are only expressed in the clone and 82 only in the normal cells. Notably, only 11 upregulated/unique proteins are encoded in the duplicated q arm of isochromosome 8 (i(8q)), which cytogenetically characterizes the clone. Since both normal and transformed brain cells release extracellular vesicles (EVs), which might induce epigenetic modifications in the neighboring cells, we also compared EVs released from transformed and normal astrocytes. Interestingly, we found that the clone releases EVs containing proteins, such as matrix metalloproteinase 3 (MMP3), that can modify the extracellular matrix, thus allowing invasion.

Proton boron capture therapy (PBCT) induces cell death and mitophagy in a heterotopic glioblastoma model

Despite aggressive therapeutic regimens, glioblastoma (GBM) represents a deadly brain tumor with significant aggressiveness, radioresistance and chemoresistance, leading to dismal prognosis. Hypoxic microenvironment, which characterizes GBM, is associated with reduced therapeutic effectiveness. Moreover, current irradiation approaches are limited by uncertain tumor delineation and severe side effects that comprehensively lead to unsuccessful treatment and to a worsening of the quality of life of GBM patients. Proton beam offers the opportunity of reduced side effects and a depth-dose profile, which, unfortunately, are coupled with low relative biological effectiveness (RBE). The use of radiosensitizing agents, such as boron-containing molecules, enhances proton RBE and increases the effectiveness on proton beam-hit targets. We report a first preclinical evaluation of proton boron capture therapy (PBCT) in a preclinical model of GBM analyzed via μ-positron emission tomography/computed tomography (μPET-CT) assisted live imaging, finding a significant increased therapeutic effectiveness of PBCT versus proton coupled with an increased cell death and mitophagy. Our work supports PBCT and radiosensitizing agents as a scalable strategy to treat GBM exploiting ballistic advances of proton beam and increasing therapeutic effectiveness and quality of life in GBM patients.

Investigating survival, quality of life and cognition in PROton versus photon therapy for IDH-mutated diffuse grade 2 and 3 GLIOmas (PRO-GLIO): a randomised controlled trial in Norway and Sweden

INTRODUCTION

The use of proton therapy increases globally despite a lack of randomised controlled trials demonstrating its efficacy and safety. Proton therapy enables sparing of non-neoplastic tissue from radiation. This is principally beneficial and holds promise of reduced long-term side effects. However, the sparing of seemingly non-cancerous tissue is not necessarily positive for isocitrate dehydrogenase (IDH)-mutated diffuse gliomas grade 2-3, which have a diffuse growth pattern. With their relatively good prognosis, yet incurable nature, therapy needs to be delicately balanced to achieve a maximal survival benefit combined with an optimised quality of life.

METHODS AND ANALYSIS

PRO-GLIO (PROton versus photon therapy in IDH-mutated diffuse grade 2 and 3 GLIOmas) is an open-label, multicentre, randomised phase III non-inferiority study. 224 patients aged 18-65 years with IDH-mutated diffuse gliomas grade 2-3 from Norway and Sweden will be randomised 1:1 to radiotherapy delivered with protons (experimental arm) or photons (standard arm). First intervention-free survival at 2 years is the primary endpoint. Key secondary endpoints are fatigue and cognitive impairment, both at 2 years. Additional secondary outcomes include several survival measures, health-related quality of life parameters and health economy endpoints.

ETHICS AND DISSEMINATION

To implement proton therapy as part of standard of care for patients with IDH-mutated diffuse gliomas grade 2-3, it should be deemed safe. With its randomised controlled design testing proton versus photon therapy, PRO-GLIO will provide important information for this patient population concerning safety, cognition, fatigue and other quality of life parameters. As proton therapy is considerably more costly than its photon counterpart, cost-effectiveness will also be evaluated. PRO-GLIO is approved by ethical committees in Norway (Regional Committee for Medical & Health Research Ethics) and Sweden (The Swedish Ethical Review Authority) and patient inclusion has commenced. Trial results will be published in international peer-reviewed journals, relevant conferences, national and international meetings and expert forums.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT05190172).

Radiation induced contrast enhancement after proton beam therapy in patients with low grade glioma - How safe are protons?

PURPOSE

The optimal treatment strategy for low-grade glioma (LGG) is still a matter of controversy. Considering that the prognosis is typically favorable, the prevention of late sequelae is of particular importance. Proton beam therapy (PRT) has the potential to further reduce the burden of treatment related side effects. We set out to evaluate the clinical outcome of proton irradiation with a particular focus on morphologic features on magnetic resonance imaging (MRI).

METHODS

We assessed prospectively 110 patients who received radiotherapy with protons for histologically proven LGG. Clinical and radiological information were analyzed resulting in more than 1200 available MRI examinations with a median follow-up of 39 months. Newly diagnosed contrast-enhancing lesions on MRI were delineated and correlated with parameters of the corresponding treatment plan. A voxel-based dose-matched paired analysis of the linear energy transfer (LET) inside vs outside lesions was performed.

RESULTS

Proton beam irradiation of patients with low-grade glioma results in overall survival (OS) of 90% after seven years. Median progression free survival had not yet been reached with surviving fraction of 54% after seven years. The incidence of temporary or clinically silent radiation induced contrast enhancement was significantly higher than previously assumed, however, symptomatic radiation necrosis was only detected in one patient. These radiation-induced contrast-enhancing lesions were almost exclusively seen at the distal beam end of the proton beam. In 22 out of 23 patients, the average LET of voxels inside contrast-enhancing lesions was significantly increased, compared to dose-matched voxels outside the lesions.

CONCLUSION

Symptomatic radiation necrosis following PRT was as rare as conventional photon-based treatment series suggest. However, the increased incidence of asymptomatic radiation-induced brain injuries with an increased average LET observed in this cohort provides strong clinical evidence to support the hypothesis that the relative biological effectiveness of protons is variable and different to the fixed factor of 1.1 currently used worldwide.

Treatment plan comparison of proton vs photon radiotherapy for lower-grade gliomas

Background and purpose

Patients with lower-grade gliomas are long-term survivors after radiotherapy and may benefit from the reduced dose to normal tissue achievable with proton therapy. Here, we aimed to quantify differences in dose to the uninvolved brain and contralateral hippocampus and compare the risk of radiation-induced secondary cancer for photon and proton plans for lower-grade glioma patients.

Materials and methods

Twenty-three patients were included in this in-silico planning comparative study and had photon and proton plans calculated (50.4 Gy(RBE = 1.1), 28 Fx) applying similar dose constraints to the target and organs at risk. Automatically calculated photon plans were generated with a 3 mm margin from clinical target volume (CTV) to planning target volume. Manual proton plans were generated using robust optimisation on the CTV. Dose metrics of organs at risk were compared using population mean dose-volume histograms and Wilcoxon signed-rank test. Secondary cancer risk per 10,000 persons per year (PPY) was estimated using dose-volume data and a risk model for secondary cancer induction.

Results

CTV coverage (V95%>98%) was similar for the two treatment modalities. Mean dose (D_mean) to the uninvolved brain was significantly reduced from 21.5 Gy (median, IQR 17.1–24.4 Gy) with photons compared to 10.3 Gy(RBE) (8.1–13.9 Gy(RBE)) with protons. D_mean to the contralateral hippocampus was significantly reduced from 6.5 Gy (5.4–11.7 Gy) with photons to 1.5 Gy(RBE) (0.4–6.8 Gy(RBE)) with protons. The estimated secondary cancer risk was reduced from 6.7 PPY (median, range 3.3–10.4 PPY) with photons to 3.0 PPY (1.3–7.5 PPY) with protons.

Conclusion

A significant reduction in mean dose to uninvolved brain and contralateral hippocampus was found with proton planning. The estimated secondary cancer risk was reduced with proton therapy.

Excellent Radiological Response with Modern Contemporary Proton Beam Therapy in Favorable Molecular Low-Intermediate Grade Oligodendroglioma: A Report of Two Cases

Radiotherapy (RT) has been a long-standing treatment option for low-grade glioma. Improvements in tumor control and reduced radiation-related toxicity can be attributed to advances in neuroimaging as well as RT treatment planning and delivery techniques. The molecular markers such as isocitrate dehydrogenase and lpl9q play a key role in determining which patients will benefit most from combined radiation and systemic therapy. We hereby report two cases of favorable molecular low-intermediate grade oligodendroglioma treated with modern proton pencil-beam therapy under high-precision image guidance showing excellent radiological response that is usually not seen with conventional photon radiation.

Health-related quality of life in patients with primary brain tumors during and three months after treatment with proton beam therapy

Background

Proton beam therapy (PBT) is increasingly administered to patients with primary brain tumors. Benefits of new treatments must be weighed against side effects and possible deterioration in health-related quality of life (HRQoL). The aim of this study was to describe and compare HRQoL, including acute symptom experiences and associated factors, in patients with malignant and benign brain tumors treated with PBT.

Materials and Methods

Adult PBT-treated patients with primary brain tumors (n = 266) were studied. HRQoL was assessed with EORTC QLQ-C30, QLQ-BN20, HADS, ISI and MFI before, during and three months after treatment. Associations with demographic and medical factors were explored.

Results

Between baseline and three months post-treatment: HRQoL decreased significantly in the global health/QOL domains physical functioning, role functioning and cognitive functioning in the malignant group, global health/QOL and physical functioning decreased significantly in the benign group, more comorbidity was significantly associated with increased motor dysfunction, leg weakness, headache and future uncertainty. Fatigue and depression were the most frequent symptoms in both groups. Independent predictors of risk factor recognition were age, sex, chemotherapy, comorbidity and education level.

Discussion

Global health/QOL in patient with brain tumors is very complex and multidimensional. Symptoms are interrelated and related to patient, tumor and treatment factors. It is important to identify aspects of HRQoL that may be affected by treatment. These include both benefits, expected to improve HRQoL, and negative changes such as symptom experience and influencing factors. Evidence-based guidelines are needed for symptom management, and for high quality of care for patients experiencing low PBT-related HRQoL.

Establishment and Preliminary Characterization of Three Astrocytic Cells Lines Obtained from Primary Rat Astrocytes by Sub-Cloning

Gliomas are complex and heterogeneous tumors that originate from the glial cells of the brain. The malignant cells undergo deep modifications of their metabolism, and acquire the capacity to invade the brain parenchyma and to induce epigenetic modifications in the other brain cell types. In spite of the efforts made to define the pathology at the molecular level, and to set novel approaches to reach the infiltrating cells, gliomas are still fatal. In order to gain a better knowledge of the cellular events that accompany astrocyte transformation, we developed three increasingly transformed astrocyte cell lines, starting from primary rat cortical astrocytes, and analyzed them at the cytogenetic and epigenetic level. In parallel, we also studied the expression of the differentiation-related H1.0 linker histone variant to evaluate its possible modification in relation with transformation. We found that the most modified astrocytes (A-FC6) have epigenetic and chromosomal alterations typical of cancer, and that the other two clones (A-GS1 and A-VV5) have intermediate properties. Surprisingly, the differentiation-specific somatic histone H1.0 steadily increases from the normal astrocytes to the most transformed ones. As a whole, our results suggest that these three cell lines, together with the starting primary cells, constitute a potential model for studying glioma development.

Proton therapy for selected low grade glioma patients in the Netherlands

Proton therapy offers an attractive alternative to conventional photon-based radiotherapy in low grade glioma patients, delivering radiotherapy with equivalent efficacy to the tumour with less radiation exposure to the brain. In the Netherlands, patients with favourable prognosis based on tumour and patient characteristics can be offered proton therapy. Radiation-induced neurocognitive function decline is a major concern in these long surviving patients. Although level 1 evidence of superior clinical outcome with proton therapy is lacking, the Dutch National Health Care Institute concluded that there is scientific evidence to assume that proton therapy can have clinical benefit by reducing radiation-induced brain damage. Based on this decision, proton therapy is standard insured care for selected low grade glioma patients. Patients with other intracranial tumours can also qualify for proton therapy, based on the same criteria. In this paper, the evidence and considerations that led to this decision are summarised. Additionally, the eligibility criteria for proton therapy and the steps taken to obtain high-quality data on treatment outcome are discussed.

Efficacy and toxicity of particle radiotherapy in WHO grade II and grade III meningiomas: a systematic review

OBJECTIVEAdjuvant radiotherapy has become a common addition to the management of high-grade meningiomas, as immediate treatment with radiation following resection has been associated with significantly improved outcomes. Recent investigations into particle therapy have expanded into the management of high-risk meningiomas. Here, the authors systematically review studies on the efficacy and utility of particle-based radiotherapy in the management of high-grade meningioma.METHODSA literature search was developed by first defining the population, intervention, comparison, outcomes, and study design (PICOS). A search strategy was designed for each of three electronic databases: PubMed, Embase, and Scopus. Data extraction was conducted in accordance with the PRISMA guidelines. Outcomes of interest included local disease control, overall survival, and toxicity, which were compared with historical data on photon-based therapies.RESULTSEleven retrospective studies including 240 patients with atypical (WHO grade II) and anaplastic (WHO grade III) meningioma undergoing particle radiation therapy were identified. Five of the 11 studies included in this systematic review focused specifically on WHO grade II and III meningiomas; the others also included WHO grade I meningioma. Across all of the studies, the median follow-up ranged from 6 to 145 months. Local control rates for high-grade meningiomas ranged from 46.7% to 86% by the last follow-up or at 5 years. Overall survival rates ranged from 0% to 100% with better prognoses for atypical than for malignant meningiomas. Radiation necrosis was the most common adverse effect of treatment, occurring in 3.9% of specified cases.CONCLUSIONSDespite the lack of randomized prospective trials, this review of existing retrospective studies suggests that particle therapy, whether an adjuvant or a stand-alone treatment, confers survival benefit with a relatively low risk for severe treatment-derived toxicity compared to standard photon-based therapy. However, additional controlled studies are needed.

Managing an altered social context-Patients experiences of staying away from home while undergoing proton beam therapy

Aim

To illuminate the experience of an altered social context for patients with primary brain tumours living away from home while undergoing proton beam therapy.

Design

A descriptive, qualitative cross-sectional interview study.

Methods

Nineteen patients were interviewed between December 2015-August 2016, either during (N = 7) or before and after (N = 12) their proton beam therapy. A hermeneutical analysis was performed.

Results

Participants made adjustments to achieve control and well-being during the treatment period. The analysis also revealed two interrelated patterns that helped participants adjust: being part of the family from a distance and seeking affinity.

Conclusion

It is important that patients receiving treatment far from home find a way to remain a part of their family and find affinity in the altered social context. Health professionals can prepare patients for the treatment period and can implement interventions to promote well-being for both patients and their relatives.

Spatial distribution of malignant transformation in patients with low-grade glioma

Background

Malignant transformation represents the natural evolution of diffuse low-grade gliomas (LGG). This is a catastrophic event, causing neurocognitive symptoms, intensified treatment and premature death. However, little is known concerning the spatial distribution of malignant transformation in patients with LGG.

Materials and methods

Patients histopathological diagnosed with LGG and subsequent radiological malignant transformation were identified from two different institutions. We evaluated the spatial distribution of malignant transformation with (1) visual inspection and (2) segmentations of longitudinal tumor volumes. In (1) a radiological transformation site < 2 cm from the tumor on preceding MRI was defined local transformation. In (2) overlap with pretreatment volume after importation into a common space was defined as local transformation. With a centroid model we explored if there were particular patterns of transformations within relevant subgroups.

Results

We included 43 patients in the clinical evaluation, and 36 patients had MRIs scans available for longitudinal segmentations. Prior to malignant transformation, residual radiological tumor volumes were > 10 ml in 93% of patients. The transformation site was considered local in 91% of patients by clinical assessment. Patients treated with radiotherapy prior to transformation had somewhat lower rate of local transformations (83%). Based upon the segmentations, the transformation was local in 92%. We did not observe any particular pattern of transformations in examined molecular subgroups.

Conclusion

Malignant transformation occurs locally and within the T2w hyperintensities in most patients. Although LGG is an infiltrating disease, this data conceptually strengthens the role of loco-regional treatments in patients with LGG.