Hypofractionated intensity-modulated radiotherapy for primary glioblastoma multiforme

Programmed cell death disrupts inflammatory tumor microenvironment (TME) and promotes glioblastoma evolution

Glioblastoma (GBM) is the most common malignant brain tumor and has a dismal prognosis even under the current first-line treatment, with a 5-year survival rate less than 7%. Therefore, it is important to understand the mechanism of treatment resistance and develop new anti-tumor strategies. Induction of programmed cell death (PCD) has become a promising anti-tumor strategy, but its effectiveness in treating GBM remains controversial. On the one hand, PCD triggers tumor cell death and then release mediators to draw in immune cells, creating a pro-inflammatory tumor microenvironment (TME). One the other hand, mounting evidence suggests that PCD and inflammatory TME will force tumor cells to evolve under survival stress, leading to tumor recurrence. The purpose of this review is to summarize the role of PCD and inflammatory TME in the tumor evolution of GBM and promising methods to overcome tumor evolution.

Safety and Efficacy of Laser Interstitial Thermal Therapy as Upfront Therapy in Primary Glioblastoma and IDH-Mutant Astrocytoma: A Meta-Analysis

Although primary studies have reported the safety and efficacy of LITT as a primary treatment in glioma, they are limited by sample sizes and institutional variation in stereotactic parameters such as temperature and laser power. The current literature has yet to provide pooled statistics on outcomes solely for primary brain tumors according to the 2021 WHO Classification of Tumors of the Central Nervous System (WHO CNS5). In the present study, we identify recent articles on primary CNS neoplasms treated with LITT without prior intervention, focusing on relationships with molecular profile, PFS, and OS. This meta-analysis includes the extraction of data from primary sources across four databases using the Covidence systematic review manager. The pooled data suggest LITT may be a safe primary management option with tumor ablation rates of 94.8% and 84.6% in IDH-wildtype glioblastoma multiforme (GBM) and IDH-mutant astrocytoma, respectively. For IDH-wildtype GBM, the pooled PFS and OS were 5.0 and 9.0 months, respectively. Similar to rates reported in the prior literature, the neurologic and non-neurologic complication rates for IDH-wildtype GBM were 10.3% and 4.8%, respectively. The neurologic and non-neurologic complication rates were somewhat higher in the IDH-mutant astrocytoma cohort at 33% and 8.3%, likely due to a smaller cohort size.

Impact of boost sequence in concurrent chemo-radiotherapy on newly diagnosed IDH-wildtype glioblastoma multiforme

BACKGROUND

The standard of care for glioblastoma multiforme (GBM) is maximal surgical resection followed by conventional fractionated concurrent chemoradiotherapy (CCRT) with a total dose of 60 Gy. However, there is currently no consensus on the optimal boost technique for CCRT in GBM.

METHODS

We conducted a retrospective review of 398 patients treated with CCRT between 2016 and 2021, using data from two institutional databases. Patients were divided into two groups: those receiving sequential boost (SEB, N = 119) and those receiving simultaneous integrated boost (SIB, N = 279). The primary endpoint was overall survival (OS). To minimize differences between the SIB and SEB groups, we conducted propensity score matching (PSM) analysis.

RESULTS

The median follow-up period was 18.6 months. Before PSM, SEB showed better OS compared to SIB (2-year, 55.6% vs. 44.5%, p = 0.014). However, after PSM, there was no significant difference between two groups (2-year, 55.6% vs. 51.5%, p = 0.300). The boost sequence was not associated with inferior OS before and after PSM (all p-values > 0.05). Additionally, the rates of symptomatic pseudo-progression were similar between the two groups (odds ratio: 1.75, p = 0.055).

CONCLUSIONS

This study found no significant difference in OS between SEB and SIB for GBM patients treated with CCRT. Further research is needed to validate these findings and to determine the optimal boost techniques for this patient population.

Predictive digital twin for optimizing patient-specific radiotherapy regimens under uncertainty in high-grade gliomas

We develop a methodology to create data-driven predictive digital twins for optimal risk-aware clinical decision-making. We illustrate the methodology as an enabler for an anticipatory personalized treatment that accounts for uncertainties in the underlying tumor biology in high-grade gliomas, where heterogeneity in the response to standard-of-care (SOC) radiotherapy contributes to sub-optimal patient outcomes. The digital twin is initialized through prior distributions derived from population-level clinical data in the literature for a mechanistic model's parameters. Then the digital twin is personalized using Bayesian model calibration for assimilating patient-specific magnetic resonance imaging data. The calibrated digital twin is used to propose optimal radiotherapy treatment regimens by solving a multi-objective risk-based optimization under uncertainty problem. The solution leads to a suite of patient-specific optimal radiotherapy treatment regimens exhibiting varying levels of trade-off between the two competing clinical objectives: (i) maximizing tumor control (characterized by minimizing the risk of tumor volume growth) and (ii) minimizing the toxicity from radiotherapy. The proposed digital twin framework is illustrated by generating an in silico cohort of 100 patients with high-grade glioma growth and response properties typically observed in the literature. For the same total radiation dose as the SOC, the personalized treatment regimens lead to median increase in tumor time to progression of around six days. Alternatively, for the same level of tumor control as the SOC, the digital twin provides optimal treatment options that lead to a median reduction in radiation dose by 16.7% (10 Gy) compared to SOC total dose of 60 Gy. The range of optimal solutions also provide options with increased doses for patients with aggressive cancer, where SOC does not lead to sufficient tumor control.

The need of radiotherapy optimization for glioblastomas considering immune responses

Glioblastoma is the most common of malignant primary brain tumors and one of the tumors with the poorest prognosis for which the overall survival rate has not significantly improved despite recent advances in treatment techniques and therapeutic drugs. Since the emergence of immune checkpoint inhibitors, the immune response to tumors has attracted increasing attention. Treatments affecting the immune system have been attempted for various tumors, including glioblastomas, but little has been shown to be effective. It has been found that the reason for this is that glioblastomas have a high ability to evade attacks from the immune system, and that the lymphocyte depletion associated with treatment can reduce its immune function. Currently, research to elucidate the resistance of glioblastomas to the immune system and development of new immunotherapies are being vigorously carried out. Targeting of radiation therapy for glioblastomas varies among guidelines and clinical trials. Based on early reports, target definitions with wide margins are common, but there are also reports that narrowing the margins does not make a significant difference in treatment outcome. It has also been suggested that a large number of lymphocytes in the blood are irradiated by the irradiation treatment to a wide area in a large number of fractionations, which may reduce the immune function, and the blood is being recognized as an organ at risk. Recently, a randomized phase II trial comparing two types of target definition in radiotherapy for glioblastomas was conducted, and it was reported that the overall survival and progression-free survival were significantly better in a small irradiation field group. We review recent findings on the immune response and the immunotherapy to glioblastomas and the novel role of radiotherapy and propose the need to develop an optimal radiotherapy that takes radiation effects on the immune function into account.

Stereotactic radiotherapy for brain metastases: predictive factors of radionecrosis

PURPOSE

Stereotactic radiotherapy (SRT) is a highly effective approach and represents the current standard of treatment for patients with limited number of brain metastasis (BM). SRT is generally well tolerated but can sometimes lead to radionecrosis (RN). The aim of this study was to identify predictive factors of radionecrosis related to SRT for brain metastasis.

METHODS

This retrospective observational cohort study included patients who underwent SRT in the Institut Sainte Catherine between January 1st, 2017 and December 31st, 2020 for the treatment of brain metastasis from any cancer. Individual data and particularly signs of radionecrosis (clinical, imaging, anatomopathological) were collected from electronic medical records. Radionecrosis was defined as the occurrence on MRI of contrast-enhancing necrotic lesions, surrounded by edema, occurring at least 6 months after SRT and localized within fields of irradiation.

RESULTS

123 patients were included; median age was 66 years. 17 patients (11.8%) developed radionecrosis after a median follow up of 418.5 days [63;1498]. Predictive factors of radionecrosis in multivariate analysis were age under 66 years with a sensitivity of 77% and a specificity of 56%. No other factor as the presence of comorbidities, the number of irradiated metastases, the PTV volume or the volume of irradiated healthy brain were predictive of radionecrosis.

CONCLUSION

Age at treatment initiation and tumor location seems to be correlated with radionecrosis in patients with brain metastasis treated with SRT. These elements could be useful to adapted radiation therapy.

Multiple therapeutic approaches of glioblastoma multiforme: From terminal to therapy

Glioblastoma multiforme (GBM) is an aggressive brain cancer showing poor prognosis. Currently, treatment methods of GBM are limited with adverse outcomes and low survival rate. Thus, advancements in the treatment of GBM are of utmost importance, which can be achieved in recent decades. However, despite aggressive initial treatment, most patients develop recurrent diseases, and the overall survival rate of patients is impossible to achieve. Currently, researchers across the globe target signaling events along with tumor microenvironment (TME) through different drug molecules to inhibit the progression of GBM, but clinically they failed to demonstrate much success. Herein, we discuss the therapeutic targets and signaling cascades along with the role of the organoids model in GBM research. Moreover, we systematically review the traditional and emerging therapeutic strategies in GBM. In addition, we discuss the implications of nanotechnologies, AI, and combinatorial approach to enhance GBM therapeutics.

Prognosis prediction for glioblastoma multiforme patients using machine learning approaches: Development of the clinically applicable model

BACKGROUND AND PURPOSE

We aimed to develop a clinically applicable prognosis prediction model predicting overall survival (OS) and progression-free survival (PFS) for glioblastoma multiforme (GBM) patients.

MATERIALS AND METHODS

All 467 patients treated with concurrent chemoradiotherapy at Yonsei Cancer Center from 2016 to 2020 were included in this study. We developed a conventional linear regression, Cox proportional hazards (COX), and non-linear machine learning algorithms, random survival forest (RSF) and survival support vector machine (SVM) based on 16 clinical variables. After backward feature selection and hyperparameter tuning using grid search, we repeated 100 times of cross-validations to combat overfitting and enhance the model performance. Harrell's concordance index (C-index) and integrated brier score (IBS) were employed as quantitative performance metrics.

RESULTS

In both predictions, RSF performed much better than COX and SVM. (For OS prediction: RSF C-index = 0.72 90%CI [0.71-0.72] and IBS = 0.12 90%CI [0.10-0.13]; For PFS prediction: RSF C-index = 0.70 90%CI [0.70-0.71] and IBS = 0.12 90%CI [0.10-0.14]). Permutation feature importance confirmed that MGMT promoter methylation, extent of resection, age, cone down planning target volume, and subventricular zone involvement are significant prognostic factors for OS. The importance of the extent of resection and MGMT promoter methylation was much higher than other selected input factors in PFS. Our final models accurately stratified two risk groups with root mean square errors less than 0.07. The sensitivity analysis revealed that our final models are highly applicable to newly diagnosed GBM patients.

CONCLUSION

Our final models can provide a reliable outcome prediction for individual GBM. The final OS and PFS predicting models we developed accurately stratify high-risk groups up to 5-years, and the sensitivity analysis confirmed that both final models are clinically applicable.

Hyperbaric Oxygen Therapy as a Complementary Treatment in Glioblastoma-A Scoping Review

Glioblastoma (GBM) is the most common and aggressive malignant brain tumor in adults. The mainstay of management for GBM is surgical resection, radiation (RT), and chemotherapy (CT). Even with optimized multimodal treatment, GBM has a high recurrence and poor survival rates ranging from 12 to 24 months in most patients. Recently, relevant advances in understanding GBM pathophysiology have opened new avenues for therapies for recurrent and newly diagnosed diseases. GBM's hypoxic microenvironment has been shown to be highly associated with aggressive biology and resistance to RT and CT. Hyperbaric oxygen therapy (HBOT) may increase anticancer therapy sensitivity by increasing oxygen tension within the hypoxic regions of the neoplastic tissue. Previous data have investigated HBOT in combination with cytostatic compounds, with an improvement of neoplastic tissue oxygenation, inhibition of HIF-1α activity, and a significant reduction in the proliferation of GBM cells. The biological effect of ionizing radiation has been reported to be higher when it is delivered under well-oxygenated rather than anoxic conditions. Several hypoxia-targeting strategies reported that HBOT showed the most significant effect that could potentially improve RT outcomes, with higher response rates and survival and no serious adverse events. However, further prospective and randomized studies are necessary to validate HBOT's effectiveness in the 'real world' GBM clinical practice.

Safety and efficacy of irradiation boost based on 18F-FET-PET in patients with newly diagnosed glioblastoma

PURPOSE

Dual timepoint FET-PET acquisition (10 and 60 minutes after FET injection) improves the definition of glioblastoma location and shape. Here we evaluated the safety and efficacy of simultaneous integrated boost (SIB) planned using dual FET-PET for postoperative glioblastoma treatment.

EXPERIMENTAL DESIGN

In this prospective pilot study (March 2017-December 2020), 17 patients qualified for FET-PET-based SIB intensity-modulated radiotherapy after resection. The prescribed dose was 78 and 60 Gy (2.6 and 2.0 Gy per fraction, respectively) for the FET-PET- and MR-based target volumes. Eleven patients had FET-PET within nine months to precisely define biological responses. Progression-free survival (PFS), overall survival (OS), toxicities, and radiation necrosis were evaluated. Six patients (35%) had tumors with MGMT promoter methylation.

RESULTS

The one- and two-year OS and PFS rates were 73% and 43% and 53% and 13%, respectively. The median OS and PFS were 24 (95%CI 9-26) and 12 (95%CI 6-18) months, respectively. Two patients developed uncontrolled seizures during radiotherapy and could not receive treatment per protocol. In patients treated per protocol, 7/15 presented with new or increased neurological deficits in the first month after irradiation. Radiation necrosis was diagnosed by MRI three months after SIB in five patients and later in another two patients. In two patients, the tumor was larger in FET-PET images after six months.

CONCLUSIONS

Survival outcomes using our novel dose escalation concept (total 78 Gy) were promising, even within the MGMTunmethylated subgroup. Excessive neurotoxicity was not observed, but radionecrosis was common and must be considered in future trials.

Moderately hypofractionated versus conventionally fractionated radiation therapy with temozolomide for young and fit patients with glioblastoma: an institutional experience and meta-analysis of literature

PURPOSE

Shorter hypofractionated radiation therapy (HF-RT) schedules may have radiobiological, patient convenience and healthcare resource advantages over conventionally fractionated radiation therapy (CF-RT) in glioblastoma (GBM). We report outcomes of young, fit GBM patients treated with HF-RT and CF-RT during the COVID-19 pandemic, and a meta-analysis of HF-RT literature in this patient subgroup.

METHODS

Hospital records of patients with IDH-wildtype GBM treated with HF-RT (50 Gy/20 fractions) and CF-RT (60 Gy/30 fractions) between January 2020 and September 2021 were reviewed. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method. Univariable analysis was performed using Cox regression analysis. A systematic search and meta-analysis of studies from January 2000 to January 2022 was performed.

RESULTS

41 patients were treated (HF-RT:15, CF-RT:26). For both HF-RT and CF-RT groups, median age was 58 years and 80-90% were ECOG 0-1. There were more methylated tumours in the HF-RT group. All patients received concurrent/adjuvant temozolomide. At 19.2 months median follow-up, median OS was 19.8 months and not-reached for HF-RT and CF-RT (p = 0.5), and median PFS was 7.7 and 5.8 months, respectively (p = 0.8). HF-RT or CF-RT did not influence OS/PFS on univariable analysis. Grade 3 radionecrosis rate was 6.7% and 7.7%, respectively. 15 of 1135 studies screened from a systematic search were eligible for meta-analysis. For studies involving temozolomide, pooled median OS and PFS with HF-RT were 17.5 and 9.9 months (927 and 862 patients). Studies using shortened HF-RT schedules reported 0-2% Grade 3 radionecrosis rates.

CONCLUSION

HF-RT may offer equivalent outcomes and reduce treatment burden compared to CF-RT in young, fit GBM patients.

Dose Escalated Radiation Therapy for Glioblastoma Multiforme: An International Systematic Review and Meta-Analysis of 22 Prospective Trials

PURPOSE

Limited evidence is available on the utility of dose-escalated radiation therapy (DE-RT) with or without temozolomide (TMZ) versus standard-of-care radiation therapy (SoC-RT) for patients with newly diagnosed glioblastoma multiforme. We performed a systematic review/meta-analysis to compare overall survival (OS) and progression-free survival (PFS) between DE-RT and SoC-RT.

METHODS AND MATERIALS

We used a Population, Intervention, Control, Outcomes, Study Design/Preferred Reporting Items for Systematic Reviews and Meta-analyses/Meta-analysis of Observational Studies in Epidemiology selection criterion to identify studies. The primary and secondary outcomes were 1-year OS and 1-year PFS, respectively. Outcomes and comparisons were subdivided based on receipt of TMZ and MGMT status. DE-RT was defined based on equivalent dose calculations. Random effects meta-analyses using the Knapp-Hartung correction, arcsine transformation, and restricted maximum likelihood method were conducted. Meta-regression was used to compare therapeutic (eg, DE-RT or TMZ) and pathologic characteristics (eg, MGMT methylation status) using the Wald-type test.

RESULTS

Across 22 published studies, 2198 patients with glioblastoma multiforme were included; 507 received DE-RT. One-year OS after DE-RT alone was higher than SoC-RT alone (46.3% vs 23.4%; P = .02) as was 1-year PFS (17.9% vs 5.3%; P = .02). No significant difference in 1-year OS (73.2% vs 64.4%; P = .23) or 1-year PFS (44.5% vs 44.3%; P = .33) between DE-RT + TMZ and SoC-RT + TMZ was noted. No difference in 1-year OS was noted between DE-RT + TMZ and SoC-RT + TMZ in either MGMT methylated (83.2% vs 73.2%; P = .23) or MGMT unmethylated (72.6% vs 50.6%; P = .16) patients.

CONCLUSIONS

DE-RT alone resulted in superior PFS and OS versus SoC-RT alone. DE-RT + TMZ did not lead to improved outcomes versus SoC-RT + TMZ. No differential benefit based on MGMT status was found. Future studies are warranted to define which subgroups benefit most from DE-RT.

A phase I/II trial of 5-fraction stereotactic radiosurgery with 5-mm margins with concurrent temozolomide in newly diagnosed glioblastoma: primary outcomes

BACKGROUND

We sought to determine the maximum tolerated dose (MTD) of 5-fraction stereotactic radiosurgery (SRS) with 5-mm margins delivered with concurrent temozolomide in newly diagnosed glioblastoma (GBM).

METHODS

We enrolled adult patients with newly diagnosed glioblastoma to 5 days of SRS in a 3 + 3 design on 4 escalating dose levels: 25, 30, 35, and 40 Gy. Dose limiting toxicity (DLT) was defined as Common Terminology Criteria for Adverse Events grades 3-5 acute or late CNS toxicity, including adverse radiation effect (ARE), the imaging correlate of radiation necrosis.

RESULTS

From 2010 to 2015, thirty patients were enrolled. The median age was 66 years (range, 51-86 y). The median target volume was 60 cm3 (range, 14.7-137.3 cm3). DLT occurred in 2 patients: one for posttreatment cerebral edema and progressive disease at 3 weeks (grade 4, dose 40 Gy); another patient died 1.5 weeks following SRS from postoperative complications (grade 5, dose 40 Gy). Late grades 1-2 ARE occurred in 8 patients at a median of 7.6 months (range 3.2-12.6 mo). No grades 3-5 ARE occurred. With a median follow-up of 13.8 months (range 1.7-64.4 mo), the median survival times were: progression-free survival, 8.2 months (95% CI: 4.6-10.5); overall survival, 14.8 months (95% CI: 10.9-19.9); O6-methylguanine-DNA methyltransferase hypermethylated, 19.9 months (95% CI: 10.5-33.5) versus 11.3 months (95% CI: 8.9-17.6) for no/unknown hypermethylation (P = 0.03), and 27.2 months (95% CI: 11.2-48.3) if late ARE occurred versus 11.7 months (95% CI: 8.9-17.6) for no ARE (P = 0.08).

CONCLUSIONS

The per-protocol MTD of 5-fraction SRS with 5-mm margins with concurrent temozolomide was 40 Gy in 5 fractions. ARE was limited to grades 1-2 and did not statistically impact survival.

Treating Glioblastoma Multiforme (GBM) with super hyperfractionated radiation therapy: Implication of temporal dose fractionation optimization including cancer stem cell dynamics

PURPOSE

A previously developed ordinary differential equation (ODE) that models the dynamic interaction and distinct radiosensitivity between cancer stem cells (CSC) and differentiated cancer cells (DCC) was used to explain the definitive treatment failure in Glioblastoma Multiforme (GBM) for conventionally and hypo-fractionated treatments. In this study, optimization of temporal dose modulation based on the ODE equation is performed to explore the feasibility of improving GBM treatment outcome.

METHODS

A non-convex optimization problem with the objective of minimizing the total cancer cell number while maintaining the normal tissue biological effective dose (BEDnormal) at 100 Gy, equivalent to the conventional 2 Gy × 30 dosing scheme was formulated. With specified total number of dose fractions and treatment duration, the optimization was performed using a paired simulated annealing algorithm with fractional doses delivered to the CSC and DCC compartments and time intervals between fractions as variables. The recurrence time, defined as the time point at which the total tumor cell number regrows to 2.8×109 cells, was used to evaluate optimization outcome. Optimization was performed for conventional treatment time frames equivalent to currently and historically utilized fractionation schemes, in which limited improvement in recurrence time delay was observed. The efficacy of a super hyperfractionated approach with a prolonged treatment duration of one year was therefore tested, with both fixed regular and optimized variable time intervals between dose fractions corresponding to total number of fractions equivalent to weekly, bi-weekly, and monthly deliveries (n = 53, 27, 13). Optimization corresponding to BEDnormal of 150 Gy was also obtained to evaluate the possibility in further recurrence delay with dose escalation.

RESULTS

For the super hyperfractionated schedules with dose fraction number equivalent to weekly, bi-weekly, and monthly deliveries, the recurrence time points were found to be 430.5, 423.9, and 413.3 days, respectively, significantly delayed compared with the recurrence time of 250.3 days from conventional fractionation. Results show that optimal outcome was achieved by first delivering infrequent fractions followed by dense once per day fractions in the middle and end of the treatment course, with sparse and low dose treatments in the between. The dose to the CSC compartment was held relatively constant throughout while larger dose fractions to the DCC compartment were observed in the beginning and final fractions that preceded large time intervals. Dose escalation to BEDnormal of 150 Gy was shown capable of further delaying recurrence time to 452 days.

CONCLUSION

The development and utilization of a temporal dose fractionation optimization framework in the context of CSC dynamics have demonstrated that substantial delay in GBM local tumor recurrence could be achieved with a super hyperfractionated treatment approach. Preclinical and clinical studies are needed to validate the efficacy of this novel treatment delivery method.

Survival after hypofractionation in glioblastoma: a systematic review and meta-analysis

BACKGROUND

Glioblastoma multiforme (GBM) has a poor prognosis despite a multi modal treatment that includes normofractionated radiotherapy. So, various hypofractionated alternatives to normofractionated RT have been tested to improve such prognosis. There is need of systematic review and meta-analysis to analyse the literature properly and maybe generalised the use of hypofractionation. The aim of this study was first, to perform a meta-analysis of all controlled trials testing the impact of hypofractionation on survival without age restriction and secondly, to analyse data from all non-comparative trials testing the impact of hypofractionation, radiosurgery and hypofractionated stereotactic RT in first line.

MATERIALS/METHODS

We searched Medline, Embase and Cochrane databases to identify all publications testing the impact of hypofractionation in glioblastoma between 1985 and March 2020. Combined hazard ratio from comparative studies was calculated for overall survival. The impact of study design, age and use of adjuvant temozolomide was explored by stratification. Meta-regressions were performed to determine the impact of prognostic factors.

RESULTS

2283 publications were identified. Eleven comparative trials were included. No impact on overall survival was evidenced (HR: 1.07, 95%CI: 0.89-1.28) without age restriction. The analysis of non-comparative literature revealed heterogeneous outcomes with limited quality of reporting. Concurrent chemotherapy, completion of surgery, immobilization device, isodose of prescription, and prescribed dose (depending on tumour volume) were poorly described. However, results on survival are encouraging and were correlated with the percentage of resected patients and with patients age but not with median dose.

CONCLUSIONS

Because few trials were randomized and because the limited quality of reporting, it is difficult to define the place of hypofactionation in glioblastoma. In first line, hypofractionation resulted in comparable survival outcome with the benefit of a shortened duration. The method used to assess hypofractionation needs to be improved.

Efficacy and Safety of Hypofractionated Radiotherapy for the Treatment of Newly Diagnosed Glioblastoma Multiforme: A Systematic Review and Meta-Analysis

Background: Hypofractionated radiotherapy (HFR) is sometimes used in the treatment of glioblastoma multiforme (GBM). The efficacy and safety of HFR is still under investigation. The aim of this systematic review and meta-analysis was to provide a comprehensive summary of the efficacy and safety of HFR, and to compare the efficacy and safety of HFR and conventional fraction radiotherapy (CFR) for the treatment of patients with GBM, based on the results of randomized controlled trials (RCTs).

Methods: A literature search was conducted to identify Phase II and III trials o comparing the efficacy and safety of HFR and CFR. Study selection, data extraction, and quality assessment, were conducted by two independent researchers. The analysis was performed using RevMan 5.3 and Stata 12.0.

Results: Sixteen Phase II and III trials were included in the systematic review, and four RCTs were included in the meta-analysis. Participants treated with HRF and CRF had comparable overall survival (OS) (hazard ratio [HR]: 0.94, 95% confidence interval [CI]: 0.72–1.22, P = 0.64) and progression-free survival (PFS) (HR: 1.09, 95% CI: 0.60–1.95, P = 0.79), and similar rates of adverse events. However, in participants aged >70 years, those who received HFR had a higher OS than those who received CFR (HR: 0.59, 95% CI: 0.37–0.93, P = 0.02).

Conclusions: HRF is efficacious and safe for the treatment of GBM. In individuals aged >70 years, treatment with HRF is superior to CFR in terms of OS. The role of HFR in the treatment of GBM in younger individuals and those with good prognostic factors requires further research.

Glioblastoma Treatment Modalities besides Surgery

Glioblastoma multiforme (GBM) is commonly known as the most aggressive primary CNS tumor in adults. The mean survival of it is 14 to 15 months, following the standard therapy from surgery, chemotherapy, to radiotherapy. Efforts in recent decades have brought many novel therapies to light, however, with limitations. In this paper, authors reviewed current treatments for GBM besides surgery. In the past decades, only radiotherapy, temozolomide (TMZ), and tumor treating field (TTF) were approved by FDA. Though promising in preclinical experiments, therapeutic effects of other novel treatments including BNCT, anti-angiogenic therapy, immunotherapy, epigenetic therapy, oncolytic virus therapy, and gene therapy are still either uncertain or discouraging in clinical results. In this review, we went through current clinical trials, underlying causes, and future therapy designs to present neurosurgeons and researchers a sketch of this field.

Efficacy of moderately hypofractionated simultaneous integrated boost intensity-modulated radiotherapy combined with temozolomide for the postoperative treatment of glioblastoma multiforme: a single-institution experience

PURPOSE

Despite recent advances in multimodal treatments, the prognosis of patients with glioblastoma multiforme (GBM) remains poor. The aim of this study was to evaluate the efficacy of moderately hypofractionated simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) combined with temozolomide (TMZ) for the postoperative treatment of GBM.

MATERIALS AND METHODS

From February 2012 to February 2018, 80 patients with newly diagnosed and histologically confirmed GBM in our institute were reviewed retrospectively. All patients underwent complete resection or partial resection surgery and then received hypofractionated SIB-IMRT with concomitant TMZ followed by adjuvant TMZ. A total dose of 64 Gy over 27 fractions was delivered to the gross tumor volume (GTV), clinical target volume 1 (CTV1) received 60 Gy over 27 fractions, and CTV2 received 54 Gy over 27 fractions. The progression-free survival (PFS) and overall survival (OS) rates and the toxicities were evaluated. Prognostic factors were analyzed using univariate and multivariate Cox models.

RESULTS

The median follow-up was 16 months (range, 5~72 months). The median PFS was 15 months, and the 1-, 2-, and 3-year PFS rates were 56.0, 27.6, and 19.5%, respectively. The median OS was 21 months, and the 1-, 2-, 3-, and 5-year OS rates were 77.6, 41.6, 32.8, and 13.4%, respectively. The toxicities were mild and acceptable. Age, KPS scores and the total number of TMZ cycles were significant factors influencing patient survival.

CONCLUSION

Moderately hypofractionated SIB-IMRT combined with TMZ is a feasible and safe treatment option with mild toxicity and good PFS and OS.

Retrospective comparison of standard and escalated doses of radiotherapy in newly diagnosed glioblastoma patients treated with concurrent and adjuvant temozolomide

BACKGROUND

To compare the efficacies of standard dose-(SDRT) and escalated dose radiotherapy (EDRT) in newly diagnosed glioblastoma (GBM) with concurrent and adjuvant temozolomide (TMZ).

MATERIALS AND METHODS

Outcomes of 126 newly diagnosed GBM patients who received SDRT (60 Gy, 30 fractions) or EDRT (70 Gy, 30 fractions) with concurrent plus adjuvant TMZ were retrospectively analyzed. Both groups received concurrent TMZ (75 mg/m2) during the course of RT and at least one course of adjuvant TMZ (150-200 mg/m2), thereafter. Overall survival (OS) and local progression free survival (LPFS) constituted the primary and secondary endpoints, respectively.

RESULTS

At median 14.2 months follow-up, 26 (20.6%) patients were alive. Median LPFS and OS were 9.2 [95% confidence interval (CI); 8.4-10.0] and 15.4 months (95% CI; 12.1-18.8), respectively, for the entire cohort. Although the median OS was numerically superior in the EDRT this difference could not reach statistical significance (22.0 vs. 14.9 months; P = 0.45), Likewise, LPFS was also (9.9 vs. 8.9 months; P = 0.89) not different between the two treatment groups. In multivariate analysis, better recursive partitioning analysis class (3-4 vs. 5; P = 0.044) and extensive surgery (gross total resection vs. subtotal resection/biopsy only; P= 0.021) were identified to associate significantly with superior OS times, irrespective of the RT protocol.

CONCLUSIONS

Although the current median OS of 22 months of the EDRT group is promising, no statistically significant survival advantage for EDRT was observed even in the presence of TMZ. Randomized studies with larger population sizes and available genetic markers are warranted to conclude more reliably on the fate of EDRT plus TMZ.

Inhibition of PI3K signalling increases the efficiency of radiotherapy in glioblastoma cells

Glioblastoma, the most common primary brain tumour, is also considered one of the most lethal cancers per se. It is highly refractory to therapeutic intervention, as highlighted by the mean patient survival of only 15 months, despite an aggressive treatment approach, consisting of maximal safe surgical resection, followed by radio- and chemotherapy. Radiotherapy, in particular, can have effects on the surviving fractions of tumour cells, which are considered adverse to the desired clinical outcome: It can induce increased cellular proliferation, as well as enhanced invasion. In this study, we established that differentiated glioblastoma cells alter their DNA repair response following repeated exposure to radiation and, therefore, high single-dose irradiation (SD-IR) is not a good surrogate marker for fractionated dose irradiation (FD-IR), as used in clinical practice. Integrating irradiation into a combination therapy approach, we then investigated whether the pharmacological inhibition of PI3K signalling, the most abundantly activated survival cascade in glioblastoma, enhances the efficacy of radiotherapy. Of note, treatment with GDC-0941, which blocks PI3K-mediated signalling, did not enhance cell death upon irradiation, but both treatment modalities functioned synergistically to reduce the total cell number. Furthermore, GDC-0941 not only prevented the radiation-induced increase in the motility of the differentiated cells, but further reduced their speed below that of untreated cells. Therefore, combining radiotherapy with the pharmacological inhibition of PI3K signalling is a potentially promising approach for the treatment of glioblastoma, as it can reduce the unwanted effects on the surviving fraction of tumour cells.

Stereotactic Radiosurgery and Hypofractionated Radiotherapy for Glioblastoma

Glioblastoma is the most common primary brain tumor in adults. Standard therapy depends on patient age and performance status but principally involves surgical resection followed by a 6-wk course of radiation therapy given concurrently with temozolomide chemotherapy. Despite such treatment, prognosis remains poor, with a median survival of 16 mo. Challenges in achieving local control, maintaining quality of life, and limiting toxicity plague treatment strategies for this disease. Radiotherapy dose intensification through hypofractionation and stereotactic radiosurgery is a promising strategy that has been explored to meet these challenges. We review the use of hypofractionated radiotherapy and stereotactic radiosurgery for patients with newly diagnosed and recurrent glioblastoma.

New Hypofractionation Radiation Strategies for Glioblastoma

PURPOSE OF REVIEW

Glioblastoma (GBM) is the most common and lethal primary brain tumor in adults, with a median survival of less than 2 years despite the standard of care treatment of 6 weeks of chemoradiotherapy. We review the data investigating hypofractionated radiotherapy (HFRT) in the treatment of newly diagnosed GBM.

RECENT FINDINGS

Investigators have explored alternative radiotherapy strategies that shorten treatment duration with the goal of similar or improved survival while minimizing toxicity. HFRT over 1-3 weeks is already a standard of care for patients with advanced age or poor performance status. For young patients with good performance status, HFRT holds the promise of radiobiologically escalating the dose and potentially improving local control while maintaining quality of life. Through the use of shorter radiotherapy fractionation regimens coupled with novel systemic agents, improved outcomes for patients with GBM may be achieved.

Remote brain microhaemorrhages may predict haematoma in glioma patients treated with radiation therapy

OBJECTIVES

To evaluate the prevalence of cerebral remote microhaemorrhages (RMH) and remote haematomas (RH) using magnetic resonance susceptibility-weighted imaging (SWI) among patients treated for gliomas during follow-up.

METHODS

We conducted a retrospective single centre longitudinal study on 58 consecutive patients treated for gliomas from January 2009 through December 2010. Our institutional review board approved this study. We evaluated the presence and number of RMH and RH found outside the brain tumour on follow-up MR imaging. We performed univariate and bivariate analyses to identify predictors for RMH and RH and Kaplan-Meier survival analysis techniques.

RESULTS

Twenty-five (43%) and four patients (7%) developed at least one RMH or RH, respectively, during follow-up. The risk was significantly higher for patients who received radiation therapy (49% and 8% versus 0%) (p = 0.02). The risk of developing RH was significantly higher in patients with at least one RMH and a high burden of RMH. The mean age of those presenting with at least one RMH or RH was significantly lower.

CONCLUSIONS

RMH were common in adult survivors of gliomas who received radiation therapy and may predict the onset of RH during follow-up, mainly in younger patients.

KEY POINTS

• Brain RMH and RH are significantly more likely to occur after RT. • RMH occur in almost half of the patients treated with RT. • RMH and RH are significantly more frequent in younger patients. • RH occur only in patients with RMH.

[Hypofractionated radiotherapy for glioblastoma: changing the radiation treatment paradigm]

Hypofractionation has the dual advantage of increased cell death with a higher dose per fraction and a reduced effect of accelerated tumor cell repopulation due to a shorter overall treatment time. However, the potential advantage may be offset by increased toxicity in the late-responding neural tissues. Recently, investigators have attempted delivering radical doses of HFRT by escalating the dose in the immediate vicinity of the enhancing tumor and postoperative surgical cavity and reported reasonable outcomes with acceptable toxicity levels. Three different studies of high-dose HFRT have reported on the paradoxical phenomenon of improved survival in patients developing radiation necrosis at the primary tumor site. The toxicity criteria of RTOG and EORTC have defined clinically or radiographically suspected radionecrosis as Grade 4 toxicity. However, most patients diagnosed with radiation necrosis in the above studies remained asymptomatic. Furthermore, the probable association with improved survival would strongly argue against adopting a blind approach for classifying radiation necrosis as Grade 4 toxicity. The data emerging from the above studies is encouraging and strongly argues for further research. However, the majority of these studies are predominantly retrospective or relatively small single-arm prospective series that add little to the overall quality of evidence. Notwithstanding the above limitations, HFRT appears to be a safe and feasible strategy for glioblastoma patients.

Hypofractionated intensity-modulated radiotherapy using simultaneous integrated boost technique with concurrent and adjuvant temozolomide for glioblastoma

Aims and background

We assessed the therapeutic efficacy of combined hypofractionated intensity-modulated radiotherapy with temozolomide in patients with primary glioblastoma.

Methods and study design

Thirty-nine patients with histologically confirmed glioblastoma were accrued. Using the simultaneous integrated boost technique, a dose of 50 Gy in 5-Gy fractions was applied to the gross tumor volume, together with 40 Gy in 4-Gy fractions and 30 Gy in 3-Gy fractions to the 1- and 2-cm margins from the gross tumor volume, respectively. Patients were also treated with concurrent temozolomide during intensity-modulated radiotherapy, followed by six cycles of adjuvant temozolomide.

Results

Median follow-up was 16.8 months (range, 4.3–54.3). Tumor progression was observed in 28 patients (71.8%), and the median time to progression was 6.8 months. Median survival was 16.8 months, and it was affected significantly by the extent of surgery. During adjuvant temozolomide treatment, 3 patients (9.7%) developed grade 3–4 hematologic or hepatic toxicity. Radiation necrosis developed in 7 patients (17.9%) and massive necrosis, requiring emergency surgery, in 1 patient (2.6%).

Conclusions

The regimen of hypofractionated intensity-modulated radiotherapy with temozolomide showed a relatively good outcome in patients with glioblastoma. Further studies are required to define the optimal fraction size for glioblastoma using this highly sophisticated radiation technique.

Hypofractionated radiotherapy with simultaneous integrated boost (SIB) plus temozolomide in good prognosis patients with glioblastoma: a multicenter phase II study by the Brain Study Group of the Italian Association of Radiation Oncology (AIRO)

INTRODUCTION

A multicenter phase II study for assessing the efficacy and the toxicity of hypofractionated radiotherapy with SIB plus temozolomide in patients with glioblastoma was carried out by the Brain Study Group of the Italian Association of Radiation Oncology.

METHODS

Twenty-four patients with newly diagnosed glioblastoma belonging to Recursive Partitioning Analysis classes III and IV were enrolled. The prescribed dose was 52.5 Gy in 15 fractions of 3.5 Gy and 67.5 in 15 fractions of 4.5 Gy to the SIB volume. Dose constraints for the hypofractionated schedule were provided. Radiotherapy was associated with concomitant and sequential temozolomide.

RESULTS

Median overall survival (OS) was 15.1 months, while median progression-free survival (PFS) was 8.6 months. Actuarial OS at 12 months was 65.6% ± 0.09, whereas actuarial PFS at 12 months was 41.2% ± 0.10. Status of methylation of MGMT promoter resulted to be a significant prognostic factor for OS. Radiotherapy-related acute toxicity was not relevant. Three patients (12.5%) had G3 myelotoxicity that required temozolomide temporary interruption or dose reduction during the chemotherapy. However, chemotherapy was not definitely discontinued for toxicity in any case. One patient out of 24 (4.2%) developed radionecrosis that required surgical resection with no evidence of disease in the surgical specimen.

CONCLUSIONS

This trial confirms that hypofractionated radiotherapy with SIB and association with temozolomide may be a reasonable and feasible option for good prognosis patients with GBM.

The radiosurgery fractionation quandary: single fraction or hypofractionation?

Stereotactic radiosurgery (SRS), typically administered in a single session, is widely employed to safely, efficiently, and effectively treat small intracranial lesions. However, for large lesions or those in close proximity to critical structures, it can be difficult to obtain an acceptable balance of tumor control while avoiding damage to normal tissue when single-fraction SRS is utilized. Treating a lesion in 2 to 5 fractions of SRS (termed "hypofractionated SRS" [HF-SRS]) potentially provides the ability to treat a lesion with a total dose of radiation that provides both adequate tumor control and acceptable toxicity. Indeed, studies of HF-SRS in large brain metastases, vestibular schwannomas, meningiomas, and gliomas suggest that a superior balance of tumor control and toxicity is observed compared with single-fraction SRS. Nonetheless, a great deal of effort remains to understand radiobiologic mechanisms for HF-SRS driving the dose-volume response relationship for tumors and normal tissues and to utilize this fundamental knowledge and the results of clinic studies to optimize HF-SRS. In particular, the application of HF-SRS in the setting of immunomodulatory cancer therapies offers special challenges and opportunities.

Phase 1/2 Trial of 5-Fraction Stereotactic Radiosurgery With 5-mm Margins With Concurrent and Adjuvant Temozolomide in Newly Diagnosed Supratentorial Glioblastoma: Health-Related Quality of Life Results

PURPOSE

We report a longitudinal assessment of health-related quality of life (HRQOL) in patients with glioblastoma (GBM) treated on a prospective dose escalation trial of 5-fraction stereotactic radiosurgery (25-40 Gy in 5 fractions) with concurrent and adjuvant temozolomide.

METHODS

HRQOL was assessed using the European Organization for Research and Treatment of Cancer (EORTC) quality of life questionnaire core-30 (QLQ-C30) general, the EORTC quality of life questionnaire-brain cancer specific module (QLQ-BN20), and the M.D. Anderson Symptom Inventory-Brain Tumor (MDASI-BT). Questionnaires were completed at baseline and at every follow-up visit after completion of radiosurgery. Changes from baseline for 9 predefined HRQOL measures (global quality of life, physical functioning, social functioning, emotional functioning, motor dysfunction, communication deficit, fatigue, insomnia, and future uncertainty) were calculated at every time point.

RESULTS

With a median follow-up time of 10.4 months (range, 0.4-52 months), 139 total HRQOL questionnaires were completed by the 30 patients on trial. Compliance with HRQOL assessment was 76% at 12 months. Communication deficit significantly worsened over time, with a decline of 1.7 points per month (P=.008). No significant changes over time were detected in the other 8 scales of our primary analysis, including global quality of life. Although 8 patients (27%) experienced adverse radiation effects (ARE) on this dose escalation trial, it was not associated with a statistically significant decline in any of the primary HRQOL scales. Disease progression was associated with communication deficit, with patients experiencing an average worsening of 13.9 points per month after progression compared with 0.7 points per month before progression (P=.01).

CONCLUSION

On this 5-fraction dose escalation protocol for newly diagnosed GBM, overall HRQOL remained stable and appears similar to historical controls of 30 fractions of radiation therapy. Tumor recurrence was associated with worsening communication deficit, and ARE did not correlate with a decline in HRQOL.

The radiosensitivity index predicts for overall survival in glioblastoma

We have previously developed a multigene expression model of tumor radiosensitivity (RSI) with clinical validation in multiple cohorts and disease sites. We hypothesized RSI would identify glioblastoma patients who would respond to radiation and predict treatment outcomes. Clinical and array based gene expression (Affymetrix HT Human Genome U133 Array Plate Set) level 2 data was downloaded from the cancer genome atlas (TCGA). A total of 270 patients were identified for the analysis: 214 who underwent radiotherapy and temozolomide and 56 who did not undergo radiotherapy. Median follow-up for the entire cohort was 9.1 months (range: 0.04–92.2 months). Patients who did not receive radiotherapy were more likely to be older (p < 0.001) and of poorer performance status (p < 0.001). On multivariate analysis, RSI is an independent predictor of OS (HR = 1.64, 95% CI 1.08–2.5; p = 0.02). Furthermore, on subset analysis, radiosensitive patients had significantly improved OS in the patients with high MGMT expression (unmethylated MGMT), 1 year OS 84.1% vs. 53.7% (p = 0.005). This observation held on MVA (HR = 1.94, 95% CI 1.19–3.31; p = 0.008), suggesting that RT has a larger therapeutic impact in these patients. In conclusion, RSI predicts for OS in glioblastoma. These data further confirm the value of RSI as a disease-site independent biomarker.

Innovative Hypofractionated Stereotactic Regimen Achieves Excellent Local Control with No Radiation Necrosis: Promising Results in the Management of Patients with Small Recurrent Inoperable GBM

Management of recurrent glioblastoma multiforme (GBM) remains a challenge. Several institutions reported that a single fraction of ≥ 20 Gy for small tumor burden results in excellent local control; however, this is at the expense of a high incidence of radiation necrosis (RN). Therefore, we developed a hypofractionation pattern of 33 Gy/3 fractions, which is a radiobiological equivalent of 20 Gy, with the aim to lower the incidence of RN. We reviewed records of 21 patients with recurrent GBM treated with hypofractionated stereotactic radiation therapy (HFSRT) to their 22 respective lesions. Sixty Gy fractioned external beam radiotherapy was performed as first-line treatment. Median time from primary irradiation to HFSRT was 9.6 months (range: 3.1 – 68.1 months). In HFSRT, a median dose of 33 Gy in 11 Gy fractions was delivered to the 80% isodose line that encompassed the target volume. The median tumor volume was 1.07 cm3 (range: 0.11 – 16.64 cm3). The median follow-up time after HFSRT was 9.3 months (range: 1.7 – 33.6 months). Twenty-one of 23 lesions treated (91.3%) achieved local control while 2/23 (8.7%) progressed. Median time to progression outside of the treated site was 5.2 months (range: 2.2 – 9.6 months). Progression was treated with salvage chemotherapy. Five of 21 patients (23.8%) were alive at the end of this follow-up; two patients remain disease-free. The remaining 16/21 patients (76.2%) died of disease. Treatment was well tolerated by all patients with no acute CTC/RTOG > Grade 2. There was 0% incidence of RN. A prospective trial will be underway to validate these promising results.

Pseudoprogression in glioblastoma patients: the impact of extent of resection

Pseudoprogression (psPD) is a radiation-induced toxicity that has substantial neurological consequence in glioblastoma (GBM) patients. MGMT promoter methylation has been shown to be an important prognostic factor of psPD, but the significance of extent of resection (EOR) remains unclear. We performed a retrospective analysis on newly diagnosed GBM patients with assessable MGMT promoter status who underwent the Stupp protocol. EOR was grouped into gross total resection (GTR), subtotal resection (STR), partial resection (PR) and stereotactic biopsy. Contrast enhancing lesion enlargement was classified as psPD or non-psPD. Among a total of 101 patients, GTR, STR, PR and stereotactic biopsy was performed in 57 (56.4%), 34 (33.7%), 9 (8.9%) and 1 patient (1%), respectively. Follow-up imaging at the end of Stupp protocol classified 45 patients (44.6%) as psPD and 56 (55.4%) as non-psPD. psPD was observed in 24 (61.5%) of 39 patients with methylated MGMT promoter and 21 (33.9%) of 62 patients with unmethylated MGMT promoter (p < 0.01). psPD was documented in 17 (29.8%), 19 (55.9%), 8 (88.9%) and 1 (100%) patient with GTR, STR, PR and stereotactic biopsy (p < 0.01), respectively. On multivariate analysis MGMT promoter status (OR 3.36, 95% CI 1.36-8.34) and EOR (OR 4.12, 95% CI 1.71-9.91) were independent predictors of psPD. A Cox proportional hazards model showed that MGMT status (HR 2.51, p < 0.01) and EOR (HR 2.99, p < 0.01) significantly influenced survival. MGMT status and EOR have a significant impact on psPD. GTR can reduce the side effects of psPD and prolong survival.

Elderly patients with glioblastoma multiforme treated with concurrent temozolomide and standard- versus abbreviated-course radiotherapy

CONTEXT

Glioblastoma multiforme (GBM) is an aggressive neoplasm, with controversy regarding treatment in elderly patients.

OBJECTIVE

To review outcomes of elderly patients aged ≥ 65 with newly diagnosed GBM treated with concurrent temozolomide and either standard-course radiotherapy (SRT) or abbreviated-course radiotherapy (ART).

DESIGN

Retrospective review from 2003 to 2012.

MAIN OUTCOME MEASURE

Survival, comparing treatment regimens. One hundred patients received SRT (median dose = 60 Gy), and 29 received ART (median dose = 35 Gy). O6- methylguanine-DNA methyltransferase (MGMT) status was available for 26 SRT and 13 ART recipients.

RESULTS

Median age was 70 years. Median follow-up was 11 months. At analysis, 3 patients were alive. Multivariate analysis of the entire cohort found SRT (hazard ratio [HR] = 0.421, p = 0.0001), Karnofsky Performance Score of 70 or higher (HR = 1.894, p = 0.0031), and more extensive surgery (HR = 0.466, p = 0.0023) were associated with longer survival time, but age was not. Median time to death with SRT was 13 months versus 5.4 months with ART, but the latter had worse prognostic factors, including lower Karnofsky Performance Scores, fewer gross total resections, and higher recursive partitioning analysis class. Recipients of SRT with methylated MGMT promoter had a trend toward longer survival compared with unmethylated MGMT (p = 0.06), but ART recipients had shorter survival with MGMT methylation (p = 0.02).

CONCLUSION

Elderly patients with multiple poor prognostic factors given ART had short survival times. Relative to other variables, MGMT status may not predict outcome for these patients.

Comparison of linear accelerator and helical tomotherapy plans for glioblastoma multiforme patients

BACKGROUND

Despite advances in radiotherapy, overall survival of glioblastoma multiforme (GBM) patients is still poor. Moreover dosimetrical analyses with these newer treatment methods are insufficient. The current study is aimed to compare intensity modulated radiation therapy (IMRT) linear accelerator (linac) and helical tomotherapy (HT) treatment plans for patients with prognostic aggressive brain tumors.

MATERIAL AND METHODS

A total of 20 GBM patient plans were prospectively evaluated in both linac and HT planning systems. Plans are compared with respect to homogenity index, conformity index and organs at risk (OAR) sparing effects of the treatments.

RESULTS

Both treatment plans provided good results that can be applied to GBM patients but it was concluded that if the critical organs with relatively lower dose constraints are closer to the target region, HT for radiotherapeutical application could be preferred.

CONCLUSION

Tomotherapy plans were superior to linear accelerator plans from the aspect of OAR sparing with slightly broader low dose ranges over the healthy tissues. In case a clinic has both of these IMRT systems, employment of HT is recommended based on the observed results and future re-irradiation strategies must be considered.

Incorporating cancer stem cells in radiation therapy treatment response modeling and the implication in glioblastoma multiforme treatment resistance

PURPOSE

To perform a preliminary exploration with a simplistic mathematical cancer stem cell (CSC) interaction model to determine whether the tumor-intrinsic heterogeneity and dynamic equilibrium between CSCs and differentiated cancer cells (DCCs) can better explain radiation therapy treatment response with a dual-compartment linear-quadratic (DLQ) model.

METHODS AND MATERIALS

The radiosensitivity parameters of CSCs and DCCs for cancer cell lines including glioblastoma multiforme (GBM), non-small cell lung cancer, melanoma, osteosarcoma, and prostate, cervical, and breast cancer were determined by performing robust least-square fitting using the DLQ model on published clonogenic survival data. Fitting performance was compared with the single-compartment LQ (SLQ) and universal survival curve models. The fitting results were then used in an ordinary differential equation describing the kinetics of DCCs and CSCs in response to 2- to 14.3-Gy fractionated treatments. The total dose to achieve tumor control and the fraction size that achieved the least normal biological equivalent dose were calculated.

RESULTS

Smaller cell survival fitting errors were observed using DLQ, with the exception of melanoma, which had a low α/β = 0.16 in SLQ. Ordinary differential equation simulation indicated lower normal tissue biological equivalent dose to achieve the same tumor control with a hypofractionated approach for 4 cell lines for the DLQ model, in contrast to SLQ, which favored 2 Gy per fraction for all cells except melanoma. The DLQ model indicated greater tumor radioresistance than SLQ, but the radioresistance was overcome by hypofractionation, other than the GBM cells, which responded poorly to all fractionations.

CONCLUSION

The distinct radiosensitivity and dynamics between CSCs and DCCs in radiation therapy response could perhaps be one possible explanation for the heterogeneous intertumor response to hypofractionation and in some cases superior outcome from stereotactic ablative radiation therapy. The DLQ model also predicted the remarkable GBM radioresistance, a result that is highly consistent with clinical observations. The radioresistance putatively stemmed from accelerated DCC regrowth that rapidly restored compartmental equilibrium between CSCs and DCCs.

Comparison of radiation regimens in the treatment of Glioblastoma multiforme: results from a single institution

Background

The optimal fractionation schedule of radiotherapy (RT) for Glioblastoma multiforme (GBM) is yet to be determined. We aim to compare different fractionation regimens and identify prognostic factors to better tailor RT for newly diagnosed GBM patients.

Methods

All data for patients who underwent surgery for GBM between January 2005 and December 2012 were compiled. Clinical information was collected using patient charts and government registry. Cox analysis was used to identify variables affecting survival and treatment outcome.

Results

The median follow-up time was 13.2 months. Two hundred and seventy-six patients met the inclusion criteria, including 147 patients in the 60 Gy in 30 fractions (ConvRT) group, 86 patients in the 60 Gy in 20 fractions (HF60) group, and 43 patients in the 40 Gy in 15 fractions (HF40) group. Median survival (MS) was 16.0 months with a median progression-free survival (PFS) of 9.23 months in the ConvRT group. This was comparable to outcome in the HF60 group with MS 15.0 months and a median PFS of 9.1 months. Patients in the HF40 group had MS of 8 months, with a median PFS 5.4 months. Cox analysis showed no significant difference in OS between the ConvRT and HF60 groups but worse outcome in the HF40 group (HR 2.22, P = 0.04). MGMT methylation, extent of resection, use of chemotherapy, and repeat surgery were found to be significant independent prognostic factors for survival.

Conclusions

HF60 constitutes a safe RT approach that shows survival comparable to standard RT while allowing for a shorter treatment time.

Re-irradiation of recurrent glioblastoma multiforme using 11C-methionine PET/CT/MRI image fusion for hypofractionated stereotactic radiotherapy by intensity modulated radiation therapy

Background

This research paper presents a valid treatment strategy for recurrent glioblastoma multiforme (GBM) using hypofractionated stereotactic radiotherapy by intensity modulated radiation therapy (HS-IMRT) planned with ¹¹C-methionine positron emission tomography (MET-PET)/computed tomography (CT)/magnetic resonance imaging (MRI) fusion.

Methods

Twenty-one patients with recurrent GBM received HS-IMRT planned by MET-PET/CT/MRI. The region of increased amino acid tracer uptake on MET-PET was defined as the gross tumor volume (GTV). The planning target volume encompassed the GTV by a 3-mm margin. Treatment was performed with a total dose of 25- to 35-Gy, given as 5- to 7-Gy daily for 5 days.

Results

With a median follow-up of 12 months, median overall survival time (OS) was 11 months from the start of HS-IMRT, with a 6-month and 1-year survival rate of 71.4% and 38.1%, respectively. Karnofsky performance status was a significant prognostic factor of OS as tested by univariate and multivariate analysis. Re-operation rate was 4.8% for radiation necrosis. No other acute or late toxicity Grade 3 or higher was observed.

Conclusions

This is the first prospective study of biologic imaging optimized HS-IMRT in recurrent GBM. HS-IMRT with PET data seems to be well tolerated and resulted in a median survival time of 11 months after HS-IMRT.

Hypofractionated high-dose irradiation with positron emission tomography data for the treatment of glioblastoma multiforme

This research paper presents clinical outcomes of hypofractionated high-dose irradiation by intensity-modulated radiation therapy (Hypo-IMRT) with ¹¹C-methionine positron emission tomography (MET-PET) data for the treatment of glioblastoma multiforme (GBM). A total of 45 patients with GBM were treated with Hypo-IMRT after surgery. Gross tumor volume (GTV) was defined as the area of enhanced lesion on MRI, including MET-PET avid region; clinical target volume (CTV) was the area with 5 mm margin surrounding the GTV; planning target volume (PTV) was the area with 15 mm margin surrounding the CTV, including MET-PET moderate region. Hypo-IMRT was performed in 8 fractions; planning the dose for GTV was escalated to 68 Gy and that for CTV was escalated to 56 Gy, while keeping the dose delivered to the PTV at 40 Gy. Concomitant and adjuvant TMZ chemotherapy was administered. At a median follow-up of 18.7 months, median overall survival (OS) was 20.0 months, and median progression-free survival was 13.0 months. The 1- and 2-year OS rates were 71.2% and 26.3%, respectively. Adjuvant TMZ chemotherapy was significantly predictive of OS on multivariate analysis. Late toxicity included 7 cases of Grade 3-4 radiation necrosis. Hypo-IMRT with MET-PET data appeared to result in favorable survival outcomes for patients with GBM.

Phase 2 trial of hypofractionated high-dose intensity modulated radiation therapy with concurrent and adjuvant temozolomide for newly diagnosed glioblastoma

PURPOSE/OBJECTIVES

To assess the effect and toxicity of hypofractionated high-dose intensity modulated radiation therapy (IMRT) with concurrent and adjuvant temozolomide (TMZ) in 46 patients with newly diagnosed glioblastoma multiforme (GBM).

METHODS AND MATERIALS

All patients underwent postsurgical hypofractionated high-dose IMRT. Three layered planning target volumes (PTVs) were contoured. PTV1 was the surgical cavity and residual tumor on T1-weighted magnetic resonance images with 5-mm margins, PTV2 was the area with 15-mm margins surrounding the PTV1, and PTV3 was the high-intensity area on fluid-attenuated inversion recovery images. Irradiation was performed in 8 fractions at total doses of 68, 40, and 32 Gy for PTV1, PTV2, and PTV3, respectively. Concurrent TMZ was given at 75 mg/m(2)/day for 42 consecutive days. Adjuvant TMZ was given at 150 to 200 mg/m(2)/day for 5 days every 28 days. Overall and progression-free survivals were evaluated.

RESULTS

No acute IMRT-related toxicity was observed. The dominant posttreatment failure pattern was dissemination. During a median follow-up time of 16.3 months (range, 4.3-80.8 months) for all patients and 23.7 months (range, 12.4-80.8 months) for living patients, the median overall survival was 20.0 months after treatment. Radiation necrosis was diagnosed in 20 patients and was observed not only in the high-dose field but also in the subventricular zone (SVZ). Necrosis in the SVZ was significantly correlated with prolonged survival (hazard ratio, 4.08; P=.007) but caused deterioration in the performance status of long-term survivors.

CONCLUSIONS

Hypofractionated high-dose IMRT with concurrent and adjuvant TMZ altered the dominant failure pattern from localized to disseminated and prolonged the survival of patients with GBM. Necrosis in the SVZ was associated with better patient survival, but the benefit of radiation to this area remains controversial.

Is current technology improving outcomes with radiation therapy for gliomas?

Radiotherapy (RT) remains the principal component of glioma treatment, and three-dimensional conformal RT (3DCRT) is the current standard of RT delivery. Advances in imaging and in RT technology have enabled more precise treatment to defined targets combined with better means of avoiding critical normal structures, and this is complemented by intensive quality assurance, which includes on-treatment imaging. The refinements of 3DCRT include intensity modulated RT (IMRT), arcing IMRT, and high-precision conformal RT, formerly described as "stereotactic," which can be delivered using a linear accelerator or other specialized equipment. Although proton therapy uses heavy charged particles, the principal application can also be considered as refinement of 3DCRT. The technologies generally improve the dose differential between the tumor and normal tissue and enable more dose-intensive treatments. However, these have not translated into improved survival outcome in patients with low- and high-grade gliomas. More intensive altered fractionation regimens have also failed to show survival benefit. Nevertheless, novel technologies enable better sparing of normal tissue and selective avoidance of critical structures, and these need to be explored further to improve the quality of life of patients with gliomas. Principal clinical advance in RT has been the recognition that less intensive treatments are beneficial for patients with adverse prognosis high-grade gliomas. We conclude that the principal gain of modern RT technology is more likely to emerge as a reduction in treatment related toxicity rather than as an improvement in overall survival; the optimal avoidance strategies remain to be defined.

Radiation and concomitant chemotherapy for patients with glioblastoma multiforme

Postoperative external beam radiotherapy was considered the standard adjuvant treatment for patients with glioblastoma multiforme until the advent of using the drug temozolomide (TMZ) in addition to radiotherapy. High-dose volume should be focal, minimizing whole brain irradiation. Modern imaging, using several magnetic resonance sequences, has improved the planning target volume definition. The total dose delivered should be in the range of 60 Gy in fraction sizes of 1.8-2.0 Gy. Currently, TMZ concomitant and adjuvant to radiotherapy has become the standard of care for glioblastoma multiforme patients. Radiotherapy dose-intensification and radiosensitizer approaches have not improved the outcome. In spite of the lack of high quality evidence, stereotactic radiotherapy can be considered for a selected group of patients. For elderly patients, data suggest that the same survival benefit can be achieved with similar morbidity using a shorter course of radiotherapy (hypofractionation). Elderly patients with tumors that exhibit methylation of the O-6-methylguanine-DNA methyltransferase promoter can benefit from TMZ alone.

Feasibility and outcomes of hypofractionated simultaneous integrated boost-intensity modulated radiotherapy for malignant gliomas: a preliminary report

PURPOSE

The aim of this study was to assess the feasibility and efficacy of hypofractionated simultaneous integrated boost-intensity modulated radiotherapy (SIB-IMRT) using three-layered planning target volumes (PTV) for malignant gliomas.

MATERIALS AND METHODS

We conducted a retrospective analysis of 12 patients (WHO grade IV-10; III-2) postoperatively treated with SIB-IMRT with concurrent temozolomide. Three-layered PTVs were contoured based on gadolinium-enhanced magnetic resonance imaging as follows; high risk PTV (H-PTV) as the area of surgical bed including residual gross tumor with a 0.5 cm margin; low risk PTV (L-PTV) as the area surrounding the high risk PTV with 1.5 cm margin; moderate risk PTV (M-PTV) as a line at one-third the distance from high risk PTV to low risk PTV. Total dose to high risk PTV was 70 Gy in 8 and 62.5 Gy in 4 patients.

RESULTS

The median follow-up time was 52 months in surviving patients. The 2- and 5-year overall survival (OS) rates were 66.6% and 47.6%, respectively. The 2- and 5-year progression-free survival (PFS) rates were 57.1% and 45.7%, respectively. The median OS and PFS were 48 and 31 months, respectively. Six patients (50%) progressed: in-field only in one, out-field or disseminated in 4, and both in one patient. All patients completed planned treatments without a toxicity-related gap. Asymptomatic radiation necrosis was observed in 4 patients at post-radiotherapy 9-31 months.

CONCLUSION

An escalated dose of hypofractionated SIB-IMRT using three-layered PTVs can be safely performed in patients with malignant glioma, and might contribute to better tumor control and survival.

MRI patterns of T1 enhancing radiation necrosis versus tumour recurrence in high-grade gliomas

INTRODUCTION

Despite the emergence of new imaging technologies, the differentiation of treatment-related changes from recurrent tumour in patients with high-grade gliomas remains a difficult challenge. We evaluated whether specific MRI (magnetic resonance imaging) T1 post-contrast enhancement patterns can help to distinguish between radiation necrosis and tumour recurrence.

METHODS

This study was approved by local institutional review board. Fifty-one patients with World Health Organization grade III-IV glioma underwent reoperation after prior chemoradiation. The percentage of radiation necrosis versus recurrent tumour in reoperation specimens was estimated by an experienced neuropathologist. Enhancement patterns on T1 post-contrast sequences from the MRIs obtained prior to reoperation were evaluated according to pathology.

RESULTS

T1 contrast enhancement patterns correlating with recurrent tumour included focal solid nodules and solid uniform enhancement with distinct margins. Eighty-five per cent (17/20) of patients with ≥70% recurrent tumour at reoperation demonstrated one of these patterns on preoperative MRI. Enhancement patterns correlating with radiation necrosis included a hazy mesh-like diffuse enhancement and rim enhancement with feathery indistinct margins. Ninety-four per cent (17/18) of patients with ≥70% radiation necrosis demonstrated one of these two patterns. Thirteen cases had more mixed pathology (>30% of tumour/necrosis) and demonstrated patterns associated with recurrence and/or necrosis. Compared to MR spectroscopy performed in 10 patients, enhancement patterns on MRI were just as accurate in predicting pathologic diagnosis.

CONCLUSION

Identifying distinct patterns of contrast enhancement on MRI may help to differentiate between radiation necrosis and tumour recurrence in high-grade gliomas.

Hypofractionated intensity modulated radiotherapy with temozolomide in newly diagnosed glioblastoma multiforme

We conducted a phase I study to determine (a) the maximum tolerated dose of peri-radiation therapy temozolomide (TMZ) and (b) the safety of a selected hypofractionated intensity modulated radiation therapy (HIMRT) regimen in glioblastoma multiforme (GBM) patients. Patients with histological diagnosis of GBM, Karnofsky performance status (KPS)≥ 60 and adequate bone marrow function were eligible for the study. All patients received peri-radiation TMZ; 1 week before the beginning of radiation therapy (RT), 1 week after RT and for 3 weeks during RT. Standard 75 mg/m(2)/day dose was administered to all patients 1 week post-RT. Dose escalation was commenced at level I: 50mg/m(2)/day, level II: 65 mg/m(2)/day and level III: 75 mg/m(2)/day for 4 weeks. HIMRT was delivered at 52.5 Gy in 15 fractions to the contrast enhancing lesion (or surgical cavity) plus the surrounding edema plus a 2 cm margin. Six men and three women with a median age of 67 years (range, 44-81) and a median KPS of 80 (range, 80-90) were enrolled. Three patients were accrued at each TMZ dose level. Median follow-up was 10 months (range, 1-15). Median progression free survival was 3.9 months (95% confidence interval [CI]: 0.9-7.4; range, 0.9-9.9 months) and the overall survival 12.7 months (95% CI: 2.5-17.6; range, 2.5-20.7 months). Time spent in a KPS ≥ 70 was 8.1 months (95% CI: 2.4-15.6; range, 2.4-16 months). No instance of irreversible grade 3 or higher acute toxicity was noted. HIMRT at 52.5 Gy in 15 fractions with peri-RT TMZ at a maximum tolerated dose of 75 mg/m(2)/day for 5 weeks is well tolerated and is able to abate treatment time for these patients.

Pseudoprogression after glioma therapy: a comprehensive review

Over the last decade, pseudoprogression as a clinically significant entity affecting both glioma patient management and the conduct of clinical trials has been recognized as a significant issue. The authors have summarized the literature relative to the incidence, chronological sequence, therapy-relatedness, impact of O-6-methylguanine-DNA methyltransferase methylation status and clinical features of pseudoprogression. Evidence regarding numerous neuroradiologic techniques to differentiate pseudoprogression from tumor recurrence is summarized. The implications of pseudoprogression on prognosis and clinical trial design are substantial, and are reviewed. Relative to this, the overlapping terms pseudoprogression and radiation necrosis are clarified to produce an appropriate basis for future consideration and research regarding this important biological phenomenon.

A volumetric study of CyberKnife hypofractionated stereotactic radiotherapy as salvage for progressive malignant brain tumors: initial experience

OBJECTIVE

Radiosurgery is frequently offered to patients with progressive malignant brain tumors if radiation therapy or chemotherapy fails to provide local control. The use of single-shot regimens, however, is limited by the risk of complications when the tumor is large, surrounded by edema or has been pre-treated with radiation. Hypofractionation may confer safety but has not been tested for these difficult tumors. We report the results of hypofractionation as an alternative option in a small cohort of progressive malignant brain tumors.

METHODS

Hypofractionated CyberKnife radiotherapy was chosen for 18 progressive malignant brain tumors (six high-grade gliomas and 12 metastatic lesions) in 15 patients because of size, previous treatment with radiation or surrounding edema. The mean dose was 21 +/- 4 Gy and the number of fractions was 5 +/- 0.6. The volume of each tumor at treatment was compared with the volume at follow-up.

RESULTS

Thirteen of the 18 tumors (72%) showed a volume decrease. The average volume change was a decrease of 16 +/- 58% (median: 20%) with a follow-up of 180 +/- 121 days (median: 172 days). Toxicity occurred in only one patient, with symptoms improving on steroids.

DISCUSSION

Progression of malignant brain tumors not ideal for single-shot radiosurgery can be arrested or reversed, at least for short periods, with minimal toxicity using hypofractionated radiotherapy. Longer studies will be needed to assess durability of this response in these difficult tumors.