Survival and failure patterns of high-grade gliomas after three-dimensional conformal radiotherapy

A Simple Automated Method for Detecting Recurrence in High-Grade Glioma

Our aim was to develop an automated multiparametric MR imaging analysis of routinely acquired imaging sequences to identify areas of focally recurrent high-grade glioma. Data from 141 patients treated with radiation therapy with a diagnosis of high-grade glioma were reviewed. Strict inclusion/exclusion criteria identified a homogeneous cohort of 12 patients with a nodular recurrence of high-grade glioma that was amenable to focal re-irradiation (cohort 1). T1WI, FLAIR, and DWI data were used to create subtraction maps across time points. Linear regression was performed to identify the pattern of change in these 3 imaging sequences that best correlated with recurrence. The ability of these parameters to guide treatment decisions in individual patients was assessed in a separate cohort of 4 patients who were treated with radiosurgery for recurrent high-grade glioma (cohort 2). A leave-one-out analysis of cohort 1 revealed that automated subtraction maps consistently predicted the radiologist-identified area of recurrence (median area under the receiver operating characteristic curve = 0.91). The regression model was tested in preradiosurgery MRI in cohort 2 and identified 8 recurrent lesions. Six lesions were treated with radiosurgery and were controlled on follow-up imaging, but the remaining 2 lesions were not treated and progressed, consistent with the predictions of the model. Multiparametric subtraction maps can predict areas of nodular progression in patients with previously treated high-grade gliomas. This automated method based on routine imaging sequences is a valuable tool to be prospectively validated in subsequent studies of treatment planning and posttreatment surveillance.

Role of STAT3 in Genesis and Progression of Human Malignant Gliomas

Signal transducer and activator of transcription 3 (STAT3) is aberrantly activated in glioblastoma and has been identified as a relevant therapeutic target in this disease and many other human cancers. After two decades of intensive research, there is not yet any approved STAT3-based glioma therapy. In addition to the canonical activation by tyrosine 705 phosphorylation, concordant reports described a potential therapeutic relevance of other post-translational modifications including mainly serine 727 phosphorylation. Such reports reinforce the need to refine the strategy of targeting STAT3 in each concerned disease. This review focuses on the role of serine 727 and tyrosine 705 phosphorylation of STAT3 in glioma. It explores their contribution to glial cell transformation and to the mechanisms that make glioma escape to both immune control and standard treatment.

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.

Quantitative Perfusion and Permeability Biomarkers in Brain Cancer from Tomographic CT and MR Images

Dynamic contrast-enhanced perfusion and permeability imaging, using computed tomography and magnetic resonance systems, are important techniques for assessing the vascular supply and hemodynamics of healthy brain parenchyma and tumors. These techniques can measure blood flow, blood volume, and blood-brain barrier permeability surface area product and, thus, may provide information complementary to clinical and pathological assessments. These have been used as biomarkers to enhance the treatment planning process, to optimize treatment decision-making, and to enable monitoring of the treatment noninvasively. In this review, the principles of magnetic resonance and computed tomography dynamic contrast-enhanced perfusion and permeability imaging are described (with an emphasis on their commonalities), and the potential values of these techniques for differentiating high-grade gliomas from other brain lesions, distinguishing true progression from posttreatment effects, and predicting survival after radiotherapy, chemotherapy, and antiangiogenic treatments are presented.

Anaplastic astrocytoma: prognostic factors and survival in 4807 patients with emphasis on receipt and impact of adjuvant therapy

To determine the receipt and impact of adjuvant therapy on overall survival (OS) for anaplastic astrocytoma (AA). Data were extracted from the National Cancer Data Base (NCDB). Chi square test, Kaplan-Meier method, and Cox regression models were employed in SPSS 22.0 (Armonk, NY: IBM Corp.) for data analyses. 4807 patients with AA diagnosed from 2004 to 2013 who underwent surgery were identified. 3243 (67.5 %) received adjuvant chemoRT, 525 (10.9 %) adjuvant radiotherapy (RT) alone, 176 (3.7 %) adjuvant chemotherapy alone and 863 (18.0 %) received no adjuvant therapy. Patients were more likely to receive adjuvant chemoRT if they were diagnosed in 2009-2013 (p = 0.022), were ≤ 50 years (p < 0.001), were male (p = 0.043), were Asian or White race (p < 0.001), had private insurance (p < 0.001), had income ≥$38,000 (p < 0.001), or underwent total resection (p < 0.003). Those who received adjuvant chemoRT had significantly better 5-year OS than the other adjuvant treatment types (41.8 % vs. 31.2 % vs. 29.8 % vs. 27.4 %, p < 0.001). This significant 5-year OS benefit was also observed regardless of age at diagnosis. Of those undergoing adjuvant chemoRT, those receiving ≥59.4 Gy had significantly better 5-year OS than those receiving <59.4 Gy (44.4 % vs. 25.9 %, p < 0.001). There was no significant difference in OS when comparing 59.4 Gy to higher RT doses. On multivariate analysis, receipt of adjuvant chemoRT, age at diagnosis, extent of disease, and insurance status were independent prognostic factors for OS. Adjuvant chemoRT is an independent prognostic factor for improved OS in AA and concomitant chemoRT should be considered for all clinically suitable patients who have undergone surgery for the disease.

Relapse patterns after radiochemotherapy of glioblastoma with FET PET-guided boost irradiation and simulation to optimize radiation target volume

Background

O-(2-18 F-fluoroethyl)-L-tyrosine-(FET)-PET may be helpful to improve the definition of radiation target volumes in glioblastomas compared with MRI. We analyzed the relapse patterns in FET-PET after a FET- and MRI-based integrated-boost intensity-modulated radiotherapy (IMRT) of glioblastomas to perform an optimized target volume definition.

Methods

A relapse pattern analysis was performed in 13 glioblastoma patients treated with radiochemotherapy within a prospective phase-II-study between 2008 and 2009. Radiotherapy was performed as an integrated-boost intensity-modulated radiotherapy (IB-IMRT). The prescribed dose was 72 Gy for the boost target volume, based on baseline FET-PET (FET-1) and 60 Gy for the MRI-based (MRI-1) standard target volume. The single doses were 2.4 and 2.0 Gy, respectively. Location and volume of recurrent tumors in FET-2 and MRI-2 were analyzed related to initial tumor, detected in baseline FET-1. Variable target volumes were created theoretically based on FET-1 to optimally cover recurrent tumor.

Results

The tumor volume overlap in FET and MRI was poor both at baseline (median 12 %; range 0–32) and at time of recurrence (13 %; 0–100). Recurrent tumor volume in FET-2 was localized to 39 % (12–91) in the initial tumor volume (FET-1). Over the time a shrinking (mean 12 (5–26) ml) and shifting (mean 6 (1–10 mm) of the resection cavity was seen. A simulated target volume based on active tumor in FET-1 with an additional safety margin of 7 mm around the FET-1 volume covered recurrent FET tumor volume (FET-2) significantly better than a corresponding target volume based on contrast enhancement in MRI-1 with a same safety margin of 7 mm (100 % (54–100) versus 85 % (0–100); p < 0.01). A simulated planning target volume (PTV), based on FET-1 and additional 7 mm margin plus 5 mm margin for setup-uncertainties was significantly smaller than the conventional, MR-based PTV applied in this study (median 160 (112–297) ml versus 231 (117–386) ml, p < 0.001).

Conclusions

In this small study recurrent tumor volume in FET-PET (FET-2) overlapped only to one third with the boost target volume, based on FET-1. The shrinking and shifting of the resection cavity may have an influence considering the limited overlap of initial and relapse tumor volume. A simulated target volume, based on FET-1 with 7 mm margin covered 100 % of relapse volume in median and led to a significantly reduced PTV, compared to MRI-based PTVs. This approach may achieve similar therapeutic efficacy but lower side effects offering a broader window to intensify concomitant systemic treatment focusing distant failures.

Recurrence patterns in patients with high-grade glioma following temozolomide-based chemoradiotherapy

There is currently no consensus regarding the optimal radiation volume for high-grade glioma (HGG). The brain volume irradiated is associated with the extent of radiation neurotoxicity. When reducing the treatment volume, the risk of geographic tumor miss should be considered. In such cases, the recurrence patterns and, particularly, the rate of marginal tumor recurrence, are important indices for determining the optimal radiation volume. In the present study, a smaller-target delineation protocol with limited margins was adopted. The postoperative enhancing tumor and resection cavity were defined as gross tumor volume (GTV); 1 and 2 cm were added to the GTV to create clinical target volume (CTV1 and CTV2), which received 60 and 54 Gy, respectively. At a median follow-up of 14 months, 54 HGG patients developed tumor recurrence. The median overall and progression-free survival were 14 and 10.5 months, respectively. A total of 34 patients developed central recurrence, 8 presented with in-field recurrence, 2 developed marginal recurrence, 2 had distant recurrence and 11 patients developed cerebrospinal fluid dissemination, 2 of whom developed central recurrence, with 1 patient simultaneously developing marginal recurrence. Local recurrence (central and in-field) was found to be the main recurrence pattern. As the rate of marginal recurrence was low (<5%), it appears that the smaller irradiated volume in the present study was appropriate. However, clinical trials investigating limited irradiation volume are required to validate our findings.

Intensity-modulated radiotherapy for gliomas:dosimetric effects of changes in gross tumor volume on organs at risk and healthy brain tissue

Aim

The aim of this study was to explore the effects of changes in the gross tumor volume (GTV) on dose distribution in organs at risk (OARs) and healthy brain tissue in patients with gliomas.

Methods

Eleven patients suffering from gliomas with intensity-modulated radiotherapy (IMRT) plans treated with a simultaneous integrated boost technique planned before therapy (initial plans) were prospectively enrolled. At the end of radiotherapy, patients underwent repeat computed tomography and magnetic resonance imaging, and IMRT was replanned. The GTV and dosimetric parameters between the initial and replanned IMRT were compared using the Wilcoxon two-related-sample test, and correlations between the initial GTV and the replanned target volumes were assessed using the bivariate correlation test.

Results

The volume of the residual tumor did not change significantly (P>0.05), the volume of the surgical cavity decreased significantly (P<0.05), and the GTV and target volumes decreased significantly at the end of IMRT (all P<0.05). The near-maximum dose to OARs and volumes of healthy brain tissue receiving total doses of 10–50 Gy were lower in the replanned IMRT than in the initial IMRT (all P<0.05). The GTV in the initial plan was significantly positively correlated with the changes in the GTV and planning target volume 1 that occurred during IMRT (all P<0.05).

Conclusion

The reduction in the GTV in patients with gliomas resulted from shrinkage of the surgical cavity during IMRT, leading to decreased doses to the OARs and healthy brain tissue. Such changes appeared to be most meaningful in patients with large initial GTV values.

Can advanced new radiation therapy technologies improve outcome of high grade glioma (HGG) patients? analysis of 3D-conformal radiotherapy (3DCRT) versus volumetric-modulated arc therapy (VMAT) in patients treated with surgery, concomitant and adjuvant chemo-radiotherapy

BACKGROUND

To assess the impact of volumetric-modulated arc therapy (VMAT) compared with 3D-conformal radiotherapy (3DCRT) in patients with newly diagnosed high grade glioma in terms of toxicity, progression free survival (PFS) and overall survival (OS).

METHODS

From March 2004 to October 2014, 341 patients underwent surgery followed by concomitant and adjuvant chemo-radiotherapy. From 2003 to 2010, 167 patients were treated using 3DCRT; starting from 2011, 174 patients underwent VMAT. The quantitative evaluation of the treatment plans was performed by means of standard dose volume histogram analysis. Response was recorded using the Response Assessment in Neuro-Oncology (RANO) criteria and toxicities graded according to Common Terminology Criteria for Adverse Event version 4.0.

RESULTS

Both techniques achieved an adequate dose conformity to the target. The median follow up time was 1.3 years; at the last observation 76 patients (23.4 %) were alive and 249 (76.6 %) dead (16 patients were lot to follow-up). For patients who underwent 3DCRT, the median PFS was 0.99 ± 0.07 years (CI95: 0.9-1.1 years); the 1 and 3 years PFS were, 49.6 ± 4 and 19.1 ± 3.1 %. This shall be compared, respectively, to 1.29 ± 0.13 years (CI95: 1.01-1.5 years), 60.8 ± 3.8, and 29.7 ± 4.6 % for patients who underwent VMAT (p = 0.02). The median OS for 3DCRT patients was 1.21 ± 0.09 years (CI95:1.03-1.3 years); 1 and 5 year OS was, 63.3 ± 3.8 and 21.5 ± 3.3 %. The corresponding results for 3DRCT patients were 1.56 ± 0.09 years (CI95:1.37-1.74 years), 73.4 ± 3.5, 30 ± 4.6 % respectively (p < 0.01). In both groups, prognostic factors conditioning PFS and OS were age, gender, KPS, histology and extent of resection (EOR).

CONCLUSIONS

VMAT resulted superior to 3DCRT in terms of dosimetric findings and clinical results.

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.

Survival in glioblastoma: a review on the impact of treatment modalities

Glioblastoma (GBM) is the most common and lethal tumor of the central nervous system. The natural history of treated GBM remains very poor with 5-year survival rates of 5 %. Survival has not significantly improved over the last decades. Currently, the best that can be offered is a modest 14-month overall median survival in patients undergoing maximum safe resection plus adjuvant chemoradiotherapy. Prognostic factors involved in survival include age, performance status, grade, specific markers (MGMT methylation, mutation of IDH1, IDH2 or TERT, 1p19q codeletion, overexpression of EGFR, etc.) and, likely, the extent of resection. Certain adjuncts to surgery, especially cortical mapping and 5-ALA fluorescence, favor higher rates of gross total resection with apparent positive impact on survival. Recurrent tumors can be offered re-intervention, participation in clinical trials, anti-angiogenic agent or local electric field therapy, without an evident impact on survival. Molecular-targeted therapies, immunotherapy and gene therapy are promising tools currently under research.

Concurrent therapy to enhance radiotherapeutic outcomes in glioblastoma

Glioblastoma is one of the most fatal and incurable human cancers characterized by nuclear atypia, mitotic activity, intense microvascular proliferation and necrosis. The current standard of care includes maximal safe surgical resection followed by radiation therapy (RT) with concurrent and adjuvant temozolomide (TMZ). The prognosis remains poor with median survival of 14.6 months with RT plus TMZ. Majority will have a recurrence within 2 years from diagnosis despite adequate treatment. Radiosensitizers, radiotherapy dose escalation and altered fractionation have failed to improve outcome. The molecular biology of glioblastoma is complex and poses treatment challenges. High rate of mutation, genotypic and phenotypic heterogeneity, rapid development of resistance, existence of blood-brain barrier (BBB), multiple intracellular and intercellular signalling pathways, over-expression of growth factor receptors, angiogenesis and antigenic diversity renders the tumor cells differentially susceptible to various treatment modalities. Thus, the treatment strategies require personalised or individualized approach based on the characteristics of tumor. Several targeted agents have been evaluated in clinical trials but the results have been modest despite these advancements. This review summarizes the current standard of care, results of concurrent chemoradiation trials, evolving innovative treatments that use targeted therapy with standard chemoradiation or RT alone, outcome of various recent trials and future outlook.

The evolving roles and controversies of radiotherapy in the treatment of glioblastoma

Numerous randomised controlled trials have demonstrated the benefit of radiation therapy in patients with newly diagnosed glioblastoma and it has been the cornerstone of treatment for decades. The aims of this review are to (1) Briefly outline the historical studies which resulted in radiation being the current standard of care as used in the Stupp et al. trial (2) Discuss the evolving role of radiation therapy in the management of elderly patients (3) Review the current evidence and ongoing studies of radiation use in the recurrent/salvage setting and (4) Discuss the continuing controversies of volume delineation in the planning of radiation delivery.

Minimizing the uncertainties regarding the effects of delaying radiotherapy for Glioblastoma: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Previous studies have provided no clear conclusions regarding the effects of delaying radiotherapy (RT) in GBM patients. We present a systematic review and meta-analysis to address the effect of delayed RT on the overall survival (OS) of GBM patients.

METHODS

A systematic search retrieved 19 retrospective studies published between 1975 and 2014 reporting on the waiting time (WT) to RT for GBM patients. The meta-analysis was performed by converting WT to RT studies intervals into a regression coefficient (β) and standard error expressing the effect size on OS per week of delay.

RESULTS

Data required to calculate the effect size on OS per week of delay were available for 12 studies (5212 patients). A non-adjusted model and a meta-regression model based on well-recognized prognostic factors were performed. No association between WT to RT, per week of delay, and OS was found (HR=0.98; 95% CI 0.90-1.08; p=0.70). The meta-regression adjusted for prognostic factors weighted by the inverse-variance (1/SE(2)) showed no clear evidence of the effect of WT to RT, per week of delay, on OS.

CONCLUSIONS

This meta-analysis, despite limitations, provided no evidence of a true effect on OS by delaying RT in GBM patients.

Polymeric drug delivery for the treatment of glioblastoma

Glioblastoma (GBM) remains an almost universally fatal diagnosis. The current therapeutic mainstay consists of maximal safe surgical resection followed by radiation therapy (RT) with concomitant temozolomide (TMZ), followed by monthly TMZ (the "Stupp regimen"). Several chemotherapeutic agents have been shown to have modest efficacy in the treatment of high-grade glioma (HGG), but blood-brain barrier impermeability remains a major delivery obstacle. Polymeric drug-delivery systems, developed to allow controlled local release of biologically active substances for a variety of conditions, can achieve high local concentrations of active agents while limiting systemic toxicities. Polymerically delivered carmustine (BCNU) wafers, placed on the surface of the tumor-resection cavity, can potentially provide immediate chemotherapy to residual tumor cells during the standard delay between surgery and chemoradiotherapy. BCNU wafer implantation as monochemotherapy (with RT) in newly diagnosed HGG has been investigated in 2 phase III studies that reported significant increases in median overall survival. A number of studies have investigated the tumoricidal synergies of combination chemotherapy with BCNU wafers in newly diagnosed or recurrent HGG, and a primary research focus has been the integration of BCNU wafers into multimodality therapy with the standard Stupp regimen. Overall, the results of these studies have been encouraging in terms of safety and efficacy. However, the data must be qualified by the nature of the studies conducted. Currently, there are no phase III studies of BCNU wafers with the standard Stupp regimen. We review the rationale, biochemistry, pharmacokinetics, and research history (including toxicity profile) of this modality.

Colony stimulating factor 1 receptor inhibition delays recurrence of glioblastoma after radiation by altering myeloid cell recruitment and polarization

BACKGROUND

Glioblastoma (GBM) may initially respond to treatment with ionizing radiation (IR), but the prognosis remains extremely poor because the tumors invariably recur. Using animal models, we previously showed that inhibiting stromal cell-derived factor 1 signaling can prevent or delay GBM recurrence by blocking IR-induced recruitment of myeloid cells, specifically monocytes that give rise to tumor-associated macrophages. The present study was aimed at determining if inhibiting colony stimulating factor 1 (CSF-1) signaling could be used as an alternative strategy to target pro-tumorigenic myeloid cells recruited to irradiated GBM.

METHODS

To inhibit CSF-1 signaling in myeloid cells, we used PLX3397, a small molecule that potently inhibits the tyrosine kinase activity of the CSF-1 receptor (CSF-1R). Combined IR and PLX3397 therapy was compared with IR alone using 2 different human GBM intracranial xenograft models.

RESULTS

GBM xenografts treated with IR upregulated CSF-1R ligand expression and increased the number of CD11b+ myeloid-derived cells in the tumors. Treatment with PLX3397 both depleted CD11b+ cells and potentiated the response of the intracranial tumors to IR. Median survival was significantly longer for mice receiving combined therapy versus IR alone. Analysis of myeloid cell differentiation markers indicated that CSF-1R inhibition prevented IR-recruited monocyte cells from differentiating into immunosuppressive, pro-angiogenic tumor-associated macrophages.

CONCLUSION

CSF-1R inhibition may be a promising strategy to improve GBM response to radiotherapy.

Dosimetric Effects of Magnetic Resonance Imaging-assisted Radiotherapy Planning: Dose Optimization for Target Volumes at High Risk and Analytic Radiobiological Dose Evaluation

Based on the assumption that apparent diffusion coefficients (ADCs) define high-risk clinical target volume (aCTVHR) in high-grade glioma in a cellularity-dependent manner, the dosimetric effects of aCTVHR-targeted dose optimization were evaluated in two intensity-modulated radiation therapy (IMRT) plans. Diffusion-weighted magnetic resonance (MR) images and ADC maps were analyzed qualitatively and quantitatively to determine aCTVHR in a high-grade glioma with high cellularity. After confirming tumor malignancy using the average and minimum ADCs and ADC ratios, the aCTVHR with double- or triple-restricted water diffusion was defined on computed tomography images through image registration. Doses to the aCTVHR and CTV defined on T1-weighted MR images were optimized using a simultaneous integrated boost technique. The dosimetric benefits for CTVs and organs at risk (OARs) were compared using dose volume histograms and various biophysical indices in an ADC map-based IMRT (IMRTADC) plan and a conventional IMRT (IMRTconv) plan. The IMRTADC plan improved dose conformity up to 15 times, compared to the IMRTconv plan. It reduced the equivalent uniform doses in the visual system and brain stem by more than 10% and 16%, respectively. The ADC-based target differentiation and dose optimization may facilitate conformal dose distribution to the aCTVHR and OAR sparing in an IMRT plan.

Outcome of Adult Brain Tumor Consortium (ABTC) prospective dose-finding trials of I-125 balloon brachytherapy in high-grade gliomas: challenges in clinical trial design and technology development when MRI treatment effect and recurrence appear similar

OBJECTIVES

The aim of this study is to define the maximal safe radiation dose to guide further study of the GliaSite balloon brachytherapy (GSBT) system in untreated newly diagnosed glioblastoma (NEW-GBM) and recurrent high-grade glioma (REC-HGG). GBST is a balloon placed in the resection cavity and later filled through a subcutaneous port with liquid I-125 Iotrex, providing radiation doses that diminish uniformly with distance from the balloon surface.

METHODS

The Adult Brain Tumor Consortium initiated prospective dose-finding studies to determine maximum tolerated dose in NEW-GBM treated before standard RT or after surgery for REC-HGG. Patients were inevaluable if there was progression before the 90-day posttreatment toxicity evaluation point.

RESULTS

Ten NEW-GBM patients had the balloon placed, and 2/10 reached the 90 day timepoint. Five REC-HGG enrolled and two were assessable at the 90-day evaluation endpoint. Imaging progression occurred before 90-day evaluation in 7/12 treated patients. The trials were closed as too few patients were assessable to allow dose escalation, although no dose-limiting toxicities (DLTs) were observed. Median survival from treatment was 15.3 months (95 % CI 7.1-23.6) for NEW-GBM and 12.8 months (95 % CI 4.2-20.9) for REC-HGG.

CONCLUSION

These trials failed to determine a maximum tolerated dose (MTD) for further testing as early imaging changes, presumed to be progression, were common and interfered with the assessment of treatment-related toxicity. The survival outcomes in these and other related studies, although based on small populations, suggest that GSBT may be worthy of further study using clinical and survival endpoints, rather than standard imaging results. The implications for local therapy development are discussed.

Increasing feasibility and utility of (18)F-FDOPA PET for the management of glioma

INTRODUCTION

Despite radical treatment therapies, glioma continues to carry with it a uniformly poor prognosis. Patients diagnosed with WHO Grade IV glioma (glioblastomas; GBM) generally succumb within two years, even those with WHO Grade III anaplastic gliomas and WHO Grade II gliomas carry prognoses of 2-5 and 2 years, respectively. PET imaging with (18)F-FDOPA allows in vivo assessment of the metabolism of glioma relative to surrounding tissues. The high sensitivity of (18)F-DOPA imaging grants utility for a number of clinical applications.

METHODS

A collection of published work about (18)F-FDOPA PET was made and a critical review was discussed and written.

RESULTS

A number of research papers have been published demonstrating that in conjunction with MRI, (18)F-FDOPA PET provides greater sensitivity and specificity than these modalities in detection, grading, prognosis and validation of treatment success in both primary and recurrent gliomas. In further comparisons with (11)C-MET, (18)F-FLT, (18)F-FET and MRI, (18)F-FDOPA has shown similar or better efficacy. Recently synthesis cassettes have become available, making (18)F-FDOPA more accessible.

CONCLUSIONS

According to the available data, (18)F-FDOPA PET is a viable radiotracer for imaging and treatment planning of gliomas.

ADVANCES IN KNOWLEDGE AND IMPLICATION FOR PATIENT CARE

(18)F-FDOPA PET appears to be a viable radiopharmaceutical for the diagnosis and treatment planning of gliomas cases, improving on that of MRI and (18)F-FDG PET.

STAT3 Serine 727 Phosphorylation: A Relevant Target to Radiosensitize Human Glioblastoma

Radiotherapy is an essential component of glioma standard treatment. Glioblastomas (GBM), however, display an important radioresistance leading to tumor recurrence. To improve patient prognosis, there is a need to radiosensitize GBM cells and to circumvent the mechanisms of resistance caused by interactions between tumor cells and their microenvironment. STAT3 has been identified as a therapeutic target in glioma because of its involvement in mechanisms sustaining tumor escape to both standard treatment and immune control. Here, we studied the role of STAT3 activation on tyrosine 705 (Y705) and serine 727 (S727) in glioma radioresistance. This study explored STAT3 phosphorylation on Y705 (pSTAT3-Y705) and S727 (pSTAT3-S727) in glioma cell lines and in clinical samples. Radiosensitizing effect of STAT3 activation down-modulation by Gö6976 was explored. In a panel of 15 human glioma cell lines, we found that the level of pSTAT3-S727 was correlated to intrinsic radioresistance. Moreover, treating GBM cells with Gö6976 resulted in a highly significant radiosensitization associated to a concomitant pSTAT3-S727 down-modulation only in GBM cell lines that exhibited no or weak pSTAT3-Y705. We report the constitutive activation of STAT3-S727 in all GBM clinical samples. Targeting pSTAT3-S727 mainly in pSTAT3-Y705-negative GBM could be a relevant approach to improve radiation therapy.

Evaluation of pre-radiotherapy apparent diffusion coefficient (ADC): patterns of recurrence and survival outcomes analysis in patients treated for glioblastoma multiforme

PURPOSE

To investigate the association of pre-radiotherapy apparent diffusion coefficient (ADC) abnormalities with patterns of recurrence and outcomes in patients with glioblastoma multiforme (GBM).

MATERIALS AND METHODS

Fifty-two patients with recurrent GBM were retrospectively evaluated. Diffusion MRI images were acquired for all patients postoperatively prior to radiotherapy. ADC images were evaluated for geographic regions of diffusion restriction (hypointensity) within the FLAIR volume. If identified, the ADC map and the T1+C MRI at the time of recurrence were registered to the original plan to determine the pattern of recurrence and the coverage of the ADC abnormality by the 60 Gy isodose line (IDL). Progression-free and overall survival was determined for patients with and without an ADC hypointensity.

RESULTS

An ADC hypointensity was identified in 32 (62%) of cases. The recurrence pattern in these cases was central in 27/32 (84%), marginal in 4/32 (13%) and distant in 1/32 (3%). The recurrence overlapped with the ADC hypointensity in 28 (88%) patients. The ADC hypointensity was covered by 95% of the 60 Gy IDL in all cases. Kaplan-Meier analysis revealed inferior progression free survival and overall survival in patients with an ADC hypointensity compared to those without, despite similarities between the groups in terms of age, RT dose, performance status, and extent of resection.

CONCLUSIONS

The presence of an ADC hypointensity on pre-radiotherapy diffusion-weighted imaging is associated with the location of tumor recurrence as demonstrated by frequent overlap in this series, and is associated with a trend toward inferior outcomes. This abnormality may reflect a high risk region of hypercellularity and warrants consideration with respect to radiotherapy planning.

Combining immunotherapy with radiation for the treatment of glioblastoma

Glioblastoma is a devastating cancer with universally poor outcomes in spite of current standard multimodal therapy. Immunotherapy is an attractive new treatment modality given its potential for exquisite specificity and its favorable side effect profile; however, clinical trials of immunotherapy in GBM have thus far shown modest benefit. Optimally combining radiation with immunotherapy may be the key to unlocking the potential of both therapies given the evidence that radiation can enhance anti-tumor immunity. Here we review this evidence and discuss considerations for combined therapy.

Surgical management of high-grade glioma: a standard of care

Neurosurgical oncology for intrinsic glioma is evolving rapidly. It must be patient-centered, consultant-led and research-orientated. The value of specialist neurosurgical engagement is becoming more widely recognized. Detailed evaluation tailored to each patient is essential before the surgical admission, in conjunction with clinical oncology input. Medical optimization, collation of magnetic resonance datasets for preoperative planning and providing an informed explanation of the proposed management and its alternatives are all part of the neurosurgeon's remit. Meticulous microsurgical technique during surgery utilizing modern neuronavigation and physiological monitoring are integral components of the specialist armamentarium. A clear understanding of the rationale for surgical intervention, including its place alongside radiotherapy and chemotherapy, informs surgical decision-making. Recognition and understanding of these issues are driving the evolution of neurosurgical management of high-grade glioma. New challenges are emerging and need to be critically evaluated in robustly designed clinical trials.

Comparison of dose distributions hippocampus in high grade gliomas irradiation with linac-based imrt and volumetric arc therapy: a dosimetric study

The aim of this study was to assess the feasibility of sparing contralateral hippocampus during partial brain radiotherapy in high grade gliomas. 20 previously treated patients were replanned to 60 Gy in 30 fractions with sparing intensity-modulated radiotherapy (IMRT) and volumetric modulated arctherapy (VMAT) using the following planning objectives: 100 % of PTV covered by 95% isodose without violating organs at risk (OAR) and hot spot dose constraints. For each, standard intensity-modulated radiotherapy (IMRT) plans were generated, as well as sparing IMRT and VMAT plans which spared contralateral (hemispheric cases) hippocampus. When the three plans were compared, there was equivalent PTV coverage, homogeneity, and conformality. Sparing IMRT significantly reduced maximum, mean, V20, V30 and V40 hippocampus doses compared with standart IMRT and VMAT (p < 0.05). VMAT significantly reduced maximum left lens and mean eye doses compared with standart IMRT and sparing IMRT (p < 0.05). Brainstem, chiasm, left and right optic nerves, right eyes and lens doses were similar. VMAT significantly reduced monitor units compared with standart IMRT and sparing IMRT (p < 0.05). It is possible to spare contralateral hippocampus during PBRT for high grade gliomas using IMRT. This approach may reduce late cognitive sequelae of cranial radiotherapy.

Evaluation of RANO response criteria compared to clinician evaluation in WHO grade III anaplastic astrocytoma: implications for clinical trial reporting and patterns of failure

The utility of current response criteria has not been established in anaplastic astrocytoma (AA). We retrospectively reviewed MR images for 20 patients with AA and compared RANO-based approaches to clinician impression described as follow: (1) standard RANO-based criteria met by growth of or development of new enhancing lesion (RANO-C), (2) RANO criteria for progression based on significant FLAIR increase (RANO-F) and (3) clinical progression usually resulting in change of treatment (Clinical). Patterns of failure (POF) were analyzed utilizing all proposed progression MRIs fused with the patients' radiotherapy treatment plan. With an overall median survival of 24.3 months, development of new enhancing lesion was the most common determinant of progression (70 % of patients). Median time to RANO-C, RANO-F and Clinical progression was 9.2, 9.2 and 11.76 months respectively. RANO-C and RANO-F preceded Clinical in 70 and 55 % of patients, respectively. In six patients (30 %) Clinical was concurrent with RANO-F; four of six also met RANO-C. POF for FLAIR component differed based on time point used to determine progression. FLAIR POF was more often marginal or distant when progression was defined clinically compared to either RANO-C or RANO-F criteria. Central POF based on FLAIR at Clinical determination of progression was associated with significantly poorer OS (9.8 vs. 34.4 months). Clinical progression occurs later than progression determined by RANO-based criteria. Evaluation of POF based on FLAIR signal abnormality at the time of clinical progression suggests central recurrences are associated with worse survival.

Radiation therapy for glioma stem cells

Radiation therapy is the most effective adjuvant treatment modality for virtually all patients with high-grade glioma. Its ability to improve patient survival has been recognized for decades. Cancer stem cells provide new insights into how tumor biology is affected by radiation and the role that this cell population can play in disease recurrence. Glioma stem cells possess a variety of intracellular mechanisms to resist and even flourish in spite of radiation, and their proliferation and maintenance appear tied to supportive stimuli from the tumor microenvironment. This chapter reviews the basis for our current use of radiation to treat high-grade gliomas, and addresses this model in the context of therapeutically resistant stem cells. We discuss the available evidence highlighting current clinical efforts to improve radiosensitivity, and newer targets worthy of further development.

Feasibility of extreme dose escalation for glioblastoma multiforme using 4π radiotherapy

Background

Glioblastoma multiforme (GBM) frequently recurs at the same location after radiotherapy. Further dose escalation using conventional methods is limited by normal tissue tolerance. 4π non-coplanar radiotherapy has recently emerged as a new potential method to deliver highly conformal radiation dose using the C-arm linacs. We aim to study the feasibility of very substantial GBM dose escalation while maintaining normal tissue tolerance using 4π.

Methods

11 GBM patients previously treated with volumetric modulated arc therapy (VMAT/RapidArc) on the NovalisTx™ platform to a prescription dose of either 59.4 Gy or 60 Gy were included. All patients were replanned with 30 non-coplanar beams using a 4π radiotherapy platform, which inverse optimizes both beam angles and fluence maps. Four different prescriptions were used including original prescription dose and PTV (4πPTV_PD), 100 Gy to the PTV and GTV (4πPTV_100Gy), 100 Gy to the GTV only while maintaining prescription dose to the rest of the PTV (4πGTV_100Gy), and a 5 mm margin expansion plan (4πPTV_PD+5mm). OARs included in the study are the normal brain (brain – PTV), brainstem, chiasm, spinal cord, eyes, lenses, optical nerves, and cochleae.

Results

The 4π plans resulted in superior dose gradient indices, as indicated by >20% reduction in the R50, compared to the clinical plans. Among all of the 4π cases, when compared to the clinical plans, the maximum and mean doses were significantly reduced (p < 0.05) by a range of 47.01-98.82% and 51.87-99.47%, respectively, or unchanged (p > 0.05) for all of the non-brain OARs. Both the 4πPTV_PD and 4π GTV_100GYplans reduced the mean normal brain mean doses.

Conclusions

4π non-coplanar radiotherapy substantially increases the dose gradient outside of the PTV and better spares critical organs. Dose escalation to 100 Gy to the GTV or additional margin expansion while meeting clinical critical organ dose constraints is feasible. 100 Gy to the PTV result in higher normal brain doses but may be tolerated when delivered in proportionally increased treatment fractions. Therefore, 4π non-coplanar radiotherapy on C-arm gantry may provide an accessible tool to improve the outcome of GBM radiotherapy through extreme dose escalation.

Use of high-resolution volumetric MR spectroscopic imaging in assessing treatment response of glioblastoma to an HDAC inhibitor

OBJECTIVE

Improved predictive imaging would enable personalization and adjustment of treatment, which are critical for patients with glioblastomain whom therapy is likely to fail. This article describes the use of MR spectroscopic imaging (MRSI) to predict early clinical and behavioral response to a therapy and an effort to develop high-resolution, volumetric MRSI to improve its clinical application.

CONCLUSION

MRSI may enable quantitative analysis of brain tumor response, offering a precise tool for monitoring of patients in clinical trials.

Anaplastic oligodendroglioma: a new treatment paradigm and current controversies

OPINION STATEMENT

Anaplastic oligodendroglial tumors have gained increasing interest with the emerging role of molecular markers and systemic chemotherapy during the past years. The long-term results of two landmark trials, RTOG 9402 and EORTC 26961, have resulted in a reconsideration of the appropriate therapeutic approaches for patients with these tumors. Both trials indicate that patients whose tumors harbor a 1p/19q co-deletion benefit particularly from the addition of procarbazine/lomustine (CCNU)/vincristine (PCV) chemotherapy to radiation therapy (RT). The median survival of patients with co-deleted tumors treated within the RTOG trial with PCV before irradiation was 14.7 years compared with 7.3 years of patients who received RT alone. Median overall survival has not been reached in the RT plus PCV arm of the EORTC trial, but a similar difference can be anticipated after a follow-up of more than 12 years. In contrast, no such benefit was observed for patients with tumors lacking 1p/19q co-deletion. Outside clinical trials, patients with anaplastic oligodendroglial tumors, and 1p/19q co-deletion therefore should be offered a combined treatment modality regimen, including radio- and chemotherapy. PCV, however, is associated with significant hematological toxicity and also nonhematological side effects, which probably translate into reduced quality of life for long-term survivors. Therefore, it might be warranted to replace PCV by temozolomide, which displays a more favorable side effect profile. Data from the NOA-04 study suggest that PCV and temozolomide have similar effects. However, long-term data on the benefit from temozolomide are lacking, making a definite answer on the equivalence of temozolomide and PCV in anaplastic oligodendroglioma (AO) impossible. The current evidence precludes RT alone for AO patients. Neither the RTOG nor the EORTC trial defined the role of chemotherapy alone. A comparison of combined modality treatment with chemotherapy alone followed by RT at progression is pending. Long-term follow-up of NOA-04 patients and results from future trials may help to clarify these questions. With more and more AO patients living 10 years or more, particular attention must be paid to late side effects, such as neurotoxicity, and careful monitoring is required for all treated patients.

Hypofractionated intensity-modulated radiotherapy with temozolomide chemotherapy may alter the patterns of failure in patients with glioblastoma multiforme

INTRODUCTION

The objective of this study was to report the patterns of failure in patients with glioblastoma multiforme (GBM) treated on a phase II trial of hypofractionated intensity-modulated radiotherapy (hypo-IMRT) with concurrent and adjuvant temozolomide (TMZ).

METHODS

Patients with newly diagnosed GBM post-resection received postoperative hypo-IMRT to 60 Gy in 10 fractions. TMZ was given concurrently at 75 mg/m(2) /day for 28 consecutive days and adjuvantly at 150-200 mg/m(2) /day for 5 days every 28 days. Radiographic failure was defined as any new T1-enhancing lesion or biopsy-confirmed progressive enhancement at the primary site. MRIs obtained at the time of failure were fused to original hypo-IMRT plans. Central, in-field, marginal and distant failure were defined as ≥95%, 80% to 95%, any to 80% and 0% of the volume of a recurrence receiving 60 Gy, respectively.

RESULTS

Twenty-four patients were treated on the trial. Median follow-up was 14.8 months (range 2.7-34.2). Seventeen of 24 patients experienced radiographic failure: one central, five in-field, two marginal, eight distant and one both in-field and distant. Two of the eight distant failures presented with leptomeningeal disease. Two other patients died without evidence of radiographic recurrence. Five of 24 patients demonstrated asymptomatic, gradually progressive in-field T1 enhancement, suggestive of post-treatment changes, without clear evidence of failure; three of these patients received a biopsy/second resection, with 100% radiation necrosis found. The median overall survival of this group was 33.0 months.

CONCLUSION

A 60-Gy hypo-IMRT treatment delivered in 6-Gy fractions with TMZ altered the patterns of failure in GBM, with more distant failures.

Patterns of failure for glioblastoma multiforme following limited-margin radiation and concurrent temozolomide

Background

To analyze patterns of failure in patients with glioblastoma multiforme (GBM) treated with limited-margin radiation therapy and concurrent temozolomide. We hypothesize that patients treated with margins in accordance with Adult Brain Tumor Consortium guidelines (ABTC) will demonstrate patterns of failure consistent with previous series of patients treated with 2–3 cm margins.

Methods

A retrospective review was performed of patients treated at the University of Alabama at Birmingham for GBM between 2000 and 2011. Ninety-five patients with biopsy-proven disease and documented disease progression after treatment were analyzed. The initial planning target volume includes the T1-enhancing tumor and surrounding edema plus a 1 cm margin. The boost planning target volume includes the T1-enhancing tumor plus a 1 cm margin. The tumors were classified as in-field, marginal, or distant if greater than 80%, 20-80%, or less than 20% of the recurrent volume fell within the 95% isodose line, respectively.

Results

The median progression-free survival from the time of diagnosis to documented failure was 8 months (range 3–46). Of the 95 documented recurrences, 77 patients (81%) had an in-field component of treatment failure, 6 (6%) had a marginal component, and 27 (28%) had a distant component. Sixty-three patients (66%) demonstrated in-field only recurrence.

Conclusions

The low rate of marginal recurrence suggests that wider margins would have little impact on the pattern of failure, validating the use of limited margins in accordance ABTC guidelines.

(1) H 2D MRSI tissue type analysis of gliomas

PURPOSE

To decompose 1H MR spectra of glioma patients into normal and abnormal tissue proportions for tumor classification and delineation.

METHODS

Anatomical imaging and 1H magnetic resonance spectroscopic imaging data have been acquired from 11 grade II and 13 grade IV glioma patients. LCModel was used to decompose the magnetic resonance spectroscopic imaging data into normal brain, grade II, and grade IV tissue proportions using a tissue type basis set. Simulations were conducted to evaluate the accuracy of the methodology. Results were visualized using colormaps and abnormality contours showing tumor grade and extent.

RESULTS

Simulations suggest that infiltrative tumor proportions as low as 20% can be identified at the typical 1H magnetic resonance spectroscopy signal-to-noise found in vivo. Tumor grading according to the highest estimated tumor grade within a lesion gave a classification accuracy of 86% discriminating between grade II and grade IV glioma. Voxels with significant proportions of tumor type spectra were found beyond the margins of contrast enhancement for most grade IV cases consistent with infiltration whereas the abnormality contours show that some tumors are confined within the hyperintensities shown by both post contrast T1 weighted and T2 weighted imaging.

CONCLUSION

LCModel can be used to decompose 1H MR spectra into proportions of normal and abnormal tissue to identify tumor extent, infiltration, and overall grade.

Mathematical modeling of PDGF-driven glioblastoma reveals optimized radiation dosing schedules

Glioblastomas (GBMs) are the most common and malignant primary brain tumors and are aggressively treated with surgery, chemotherapy, and radiotherapy. Despite this treatment, recurrence is inevitable and survival has improved minimally over the last 50 years. Recent studies have suggested that GBMs exhibit both heterogeneity and instability of differentiation states and varying sensitivities of these states to radiation. Here, we employed an iterative combined theoretical and experimental strategy that takes into account tumor cellular heterogeneity and dynamically acquired radioresistance to predict the effectiveness of different radiation schedules. Using this model, we identified two delivery schedules predicted to significantly improve efficacy by taking advantage of the dynamic instability of radioresistance. These schedules led to superior survival in mice. Our interdisciplinary approach may also be applicable to other human cancer types treated with radiotherapy and, hence, may lay the foundation for significantly increasing the effectiveness of a mainstay of oncologic therapy. PAPERCLIP:

Malignant gliomas: current perspectives in diagnosis, treatment, and early response assessment using advanced quantitative imaging methods

Malignant gliomas consist of glioblastomas, anaplastic astrocytomas, anaplastic oligodendrogliomas and anaplastic oligoastrocytomas, and some less common tumors such as anaplastic ependymomas and anaplastic gangliogliomas. Malignant gliomas have high morbidity and mortality. Even with optimal treatment, median survival is only 12–15 months for glioblastomas and 2–5 years for anaplastic gliomas. However, recent advances in imaging and quantitative analysis of image data have led to earlier diagnosis of tumors and tumor response to therapy, providing oncologists with a greater time window for therapy management. In addition, improved understanding of tumor biology, genetics, and resistance mechanisms has enhanced surgical techniques, chemotherapy methods, and radiotherapy administration. After proper diagnosis and institution of appropriate therapy, there is now a vital need for quantitative methods that can sensitively detect malignant glioma response to therapy at early follow-up times, when changes in management of nonresponders can have its greatest effect. Currently, response is largely evaluated by measuring magnetic resonance contrast and size change, but this approach does not take into account the key biologic steps that precede tumor size reduction. Molecular imaging is ideally suited to measuring early response by quantifying cellular metabolism, proliferation, and apoptosis, activities altered early in treatment. We expect that successful integration of quantitative imaging biomarker assessment into the early phase of clinical trials could provide a novel approach for testing new therapies, and importantly, for facilitating patient management, sparing patients from weeks or months of toxicity and ineffective treatment. This review will present an overview of epidemiology, molecular pathogenesis and current advances in diagnoses, and management of malignant gliomas.

In vivo radiation response of proneural glioma characterized by protective p53 transcriptional program and proneural-mesenchymal shift

Glioblastoma is the most common adult primary brain tumor and has a dismal median survival. Radiation is a mainstay of treatment and significantly improves survival, yet recurrence is nearly inevitable. Better understanding the radiation response of glioblastoma will help improve strategies to treat this devastating disease. Here, we present a comprehensive study of the in vivo radiation response of glioma cells in a mouse model of proneural glioblastoma. These tumors are a heterogeneous mix of cell types with differing radiation sensitivities. To explicitly study the gene expression changes comprising the radiation response of the Olig2(+) tumor bulk cells, we used translating ribosome affinity purification (TRAP) from Olig2-TRAP transgenic mice. Comparing both ribosome-associated and total pools of mRNA isolated from Olig2(+) cells indicated that the in vivo gene expression response to radiation occurs primarily at the total transcript level. Genes related to apoptosis and cell growth were significantly altered. p53 and E2F were implicated as major regulators of the radiation response, with p53 activity needed for the largest gene expression changes after radiation. Additionally, radiation induced a marked shift away from a proneural expression pattern toward a mesenchymal one. This shift occurs in Olig2(+) cells within hours and in multiple genetic backgrounds. Targets for Stat3 and CEBPB, which have been suggested to be master regulators of a mesenchymal shift, were also up-regulated by radiation. These data provide a systematic description of the events following radiation and may be of use in identifying biological processes that promote glioma radioresistance.

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.

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.

For the next trick: new discoveries in radiobiology applied to glioblastoma

Glioblastoma (GBM) is the most common malignant brain tumor. Radiotherapy post surgical resection remained the mainstay of the management of GBM for decades until the addition of temozolomide was shown to prolong the median overall survival (OS) by 2.5 months to 14.6 months in 2005. Infiltrative growth to surrounding normal brain tissue and cooption of vascular niches, peripheral microvasuclar hyperplasia, and central hypoxic regions with pseudopalisading necrosis are characteristics of GBM and are causally linked to their exceptional radio- and chemo-resistant phenotype. An intratumoral hierarchy is postulated consisting of tumor stem cells in the apex with high DNA-repair proficiency resisting radiotherapy. It is conceivable that the stem cell property is more dynamic than originally anticipated. Niche effects such as exposure to hypoxia and intercellular communication in proximities to endothelial or bone marrow-derived cells (BMDC), for example, may activate such "stem cell" programs. GBM are exceptionally stroma-rich tumors and may consist of more than 70% stroma components, such as microglia and BMDC. It becomes increasingly apparent that treatment of GBM needs to integrate therapies targeting all above-mentioned distinct pathophysiological features. Accordingly, recent approaches in GBM therapy include inhibition of invasion (e.g., integrin, EGFR, CD95, and mTOR inhibition), antiangiogenesis and stroma modulators (TGFbeta, VEGF, angiopoetin, cMET inhibitors) and activation of immune response (vaccination and blockage of negative co-stimulatory signals). In addition, high LET-radiotherapy, for example with carbon ions, is postulated to ablate tumor stem cell and hypoxic cells more efficiently as compared with conventional low-LET photon irradiation. We discuss current key concepts, their limitations, and potentials to improve the outcome in this rapidly progressive and devastating disease.

Toward patient-specific, biologically optimized radiation therapy plans for the treatment of glioblastoma

PURPOSE

To demonstrate a method of generating patient-specific, biologically-guided radiotherapy dose plans and compare them to the standard-of-care protocol.

METHODS AND MATERIALS

We integrated a patient-specific biomathematical model of glioma proliferation, invasion and radiotherapy with a multiobjective evolutionary algorithm for intensity-modulated radiation therapy optimization to construct individualized, biologically-guided plans for 11 glioblastoma patients. Patient-individualized, spherically-symmetric simulations of the standard-of-care and optimized plans were compared in terms of several biological metrics.

RESULTS

The integrated model generated spatially non-uniform doses that, when compared to the standard-of-care protocol, resulted in a 67% to 93% decrease in equivalent uniform dose to normal tissue, while the therapeutic ratio, the ratio of tumor equivalent uniform dose to that of normal tissue, increased between 50% to 265%. Applying a novel metric of treatment response (Days Gained) to the patient-individualized simulation results predicted that the optimized plans would have a significant impact on delaying tumor progression, with increases from 21% to 105% for 9 of 11 patients.

CONCLUSIONS

Patient-individualized simulations using the combination of a biomathematical model with an optimization algorithm for radiation therapy generated biologically-guided doses that decreased normal tissue EUD and increased therapeutic ratio with the potential to improve survival outcomes for treatment of glioblastoma.

Evaluation of outcome and prognostic factors in patients of glioblastoma multiforme: A single institution experience

Aims:

We present retrospective analysis of patients of glioblastoma multiforme (GBM) and discuss clinical characteristics, various treatment protocols, survival outcomes, and prognostic factors influencing survival.

Materials and Methods:

From January 2002 to June 2009, 439 patients of GBM were registered in our department. The median age of patients was 50 years, 66.1% were males, and 75% underwent complete or near-total excision. We evaluated those 360 patients who received radiotherapy (RT). Radiotherapy schedule was selected depending upon pre-RT Karnofsky Performance Status (KPS). Patients with KPS < 70 (Group I, n = 48) were planned for RT dose of 30-35 Gy in 10-15 fractions, and patients with KPS ≥ 70 (Group II, n = 312) were planned for 60 Gy in 30 fractions. In group I, six patients and in group II, 89 patients received some form of chemotherapy (lomustine or temozolomide).

Statistical Analysis Used:

Statistical analysis was done using Statistical Package for Social Sciences, version 12.0. Overall survival (OS) was calculated using Kaplan-Meier method, and prognostic factors were determined by log rank test. The Cox proportional hazards model was used for multivariate analysis.

Results:

The median follow-up was 7.53 months. The median and 2-year survival rates were 6.33 months and 2.24% for group I and 7.97 months and 8.21% for group II patients, respectively (P = 0.001). In multivariate analysis, site of tumor (central vs. others; P = 0.006), location of tumor (parietal lobe vs. others; P = 0.003), RT dose (<60 Gy vs. 60 Gy; P = 0.0001), and use of some form of chemotherapy (P = 0.0001) were independent prognostic factors for survival.

Conclusions:

In patients with GBM, OS and prognosis remains dismal. Whenever possible, we should use concurrent and/or adjuvant chemotherapy to maximize the benefits of post-operative radiotherapy. Patients with poor performance status may be considered for hypofractionated RT schedules, which have similar median survival rates as conventional RT.

Stereotactic body radiation therapy for primary and metastatic liver tumors

OBJECTIVES

The full potential of stereotactic body radiation therapy (SBRT), in the treatment of unresectable intrahepatic malignancies, has yet to be realized as our experience is still limited. Thus, we evaluated SBRT outcomes for primary and metastatic liver tumors, with the goal of identifying factors that may aid in optimization of therapy.

METHODS

From 2005 to 2010, 62 patients with 106 primary and metastatic liver tumors were treated with SBRT to a median biologic effective dose (BED) of 100 Gy (42.6-180). The majority of patients received either three (47%) or five fractions (48%). Median gross tumor volume (GTV) was 8.8 cm(3) (0.2-222.4).

RESULTS

With a median follow-up of 18 months (0.46-46.8), freedom from local progression (FFLP) was observed in 97 of 106 treated tumors, with 1- and 2-year FFLP rates of 93% and 82%. Median overall survival (OS) for all patients was 25.2 months, with 1- and 2-year OS of 81% and 52%. Neither BED nor GTV significantly predicted for FFLP. Local failure was associated with a higher risk of death [hazard ratio (HR) = 5.1, P = .0007]. One Child-Pugh Class B patient developed radiation-induced liver disease. There were no other significant toxicities.

CONCLUSIONS

SBRT provides excellent local control for both primary and metastatic liver lesions with minimal toxicity. Future studies should focus on appropriate selection of patients and on careful assessment of liver function to maximize both the safety and efficacy of treatment.

Concurrent bevacizumab and temozolomide alter the patterns of failure in radiation treatment of glioblastoma multiforme

Background

We investigated the pattern of failure in glioblastoma multiforma (GBM) patients treated with concurrent radiation, bevacizumab (BEV), and temozolomide (TMZ). Previous studies demonstrated a predominantly in-field pattern of failure for GBM patients not treated with concurrent BEV.

Methods

We reviewed the treatment of 23 patients with GBM who received 30 fractions of simultaneous integrated boost IMRT. PTV60 received 2 Gy daily to the tumor bed or residual tumor while PTV54 received 1.8 Gy daily to the surrounding edema. Concurrent TMZ (75 mg/m^2) daily and BEV (10 mg/kg every 2 weeks) were given during radiation therapy. One month after RT completion, adjuvant TMZ (150 mg/m^2 × 5 days) and BEV were delivered monthly until progression or 12 months total.

Results

With a median follow-up of 12 months, the median disease-free and overall survival were not reached. Four patients discontinued therapy due to toxicity for the following reasons: bone marrow suppression (2), craniotomy wound infection (1), and pulmonary embolus (1). Five patients had grade 2 or 3 hypertension managed by oral medications. Of the 12 patients with tumor recurrence, 7 suffered distant failure with either subependymal (5/12; 41%) or deep white matter (2/12; 17%) spread detected on T2 FLAIR sequences. Five of 12 patients (41%) with a recurrence demonstrated evidence of GAD enhancement. The patterns of failure did not correlate with extent of resection or number of adjuvant cycles.

Conclusions

Treatment of GBM patients with concurrent radiation, BEV, and TMZ was well tolerated in the current study. The majority of patients experienced an out-of-field pattern of failure with radiation, BEV, and TMZ which has not been previously reported. Further investigation is warranted to determine whether BEV alters the underlying tumor biology to improve survival. These data may indicate that the currently used clinical target volume thought to represent microscopic disease for radiation may not be appropriate in combination with TMZ and BEV.

Ionizing radiation in glioblastoma initiating cells

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults with a median survival of 12-15 months with treatment consisting of surgical resection followed by ionizing radiation (IR) and chemotherapy. Even aggressive treatment is often palliative due to near universal recurrence. Therapeutic resistance has been linked to a subpopulation of GBM cells with stem cell-like properties termed GBM initiating cells (GICs). Recent efforts have focused on elucidating resistance mechanisms activated in GICs in response to IR. Among these, GICs preferentially activate the DNA damage response (DDR) to result in a faster rate of double-strand break (DSB) repair induced by IR as compared to the bulk tumor cells. IR also activates NOTCH and the hepatic growth factor (HGF) receptor, c-MET, signaling cascades that play critical roles in promoting proliferation, invasion, and resistance to apoptosis. These pathways are preferentially activated in GICs and represent targets for pharmacologic intervention. While IR provides the benefit of improved survival, it paradoxically promotes selection of more malignant cellular phenotypes of GBM. As reviewed here, finding effective combinations of radiation and molecular inhibitors to target GICs and non-GICs is essential for the development of more effective therapies.

Morphologic MRI features, diffusion tensor imaging and radiation dosimetric analysis to differentiate pseudo-progression from early tumor progression

Pseudo-progression (PsP) refers to the paradoxical increase of contrast enhancement within 12 weeks of chemo-radiation therapy in gliomas attributable to treatment effects rather than early tumor progression (ETP). This study was performed to evaluate the utility of morphologic imaging features, diffusion tensor imaging (DTI) and radiation dosimetric analysis of magnetic resonance imaging (MRI) changes in differentiating PsP from ETP. Serial MRI examinations of 163 patients treated for high-grade glioma were reviewed. 46 patients showed a recurrent or progressive enhancing lesion within 12 weeks of radiotherapy. We used an in-house modified scoring system based on 20 different morphologic features (modified VASARI features) to assess the MRI studies. DTI analyses were performed in 24 patients. MRI changes were defined as recurrent volume (Vrec) and registered with pretreatment computed tomography dataset, and the actual dose received by the Vrec during treatment was calculated using dose-volume histograms. Bidimensional product of T2-FLAIR signal abnormality and enhancing component was larger in the ETP group. DTI metrics revealed no significant difference between the two groups. There was no statistically significant difference in the location of Vrec between PsP and ETP groups. Morphologic MRI features and DTI have a limited role in differentiating between PsP and ETP. The larger sizes of the T2-FLAIR signal abnormality and the enhancing component of the lesion favor ETP. There was no correlation between the pattern of MRI changes and radiation dose distribution between PsP and ETP groups.

A phase I study of the combination of sorafenib with temozolomide and radiation therapy for the treatment of primary and recurrent high-grade gliomas

PURPOSE

Despite recent advances in the management of high-grade and recurrent gliomas, survival remains poor. Antiangiogenic therapy has been shown to be efficacious in the treatment of high-grade gliomas both in preclinical models and in clinical trials. We sought to determine the safety and maximum tolerated dose of sorafenib when combined with both radiation and temozolomide in the primary setting or radiation alone in the recurrent setting.

METHODS AND MATERIALS

This was a preclinical study and an open-label phase I dose escalation trial. Multiple glioma cell lines were analyzed for viability after treatment with radiation, temozolomide, or sorafenib or combinations of them. For patients with primary disease, sorafenib was given concurrently with temozolomide (75 mg/m(2)) and 60 Gy radiation, for 30 days after completion of radiation. For patients with recurrent disease, sorafenib was combined with a hypofractionated course of radiation (35 Gy in 10 fractions).

RESULTS

Cell viability was significantly reduced with the combination of radiation, temozolomide, and sorafenib or radiation and sorafenib. Eighteen patients (11 in the primary cohort, 7 in the recurrent cohort) were enrolled onto this trial approved by the institutional review board. All patients completed the planned course of radiation therapy. The most common toxicities were hematologic, fatigue, and rash. There were 18 grade 3 or higher toxicities. The median overall survival was 18 months for the entire population.

CONCLUSIONS

Sorafenib can be safely combined with radiation and temozolomide in patients with high-grade glioma and with radiation alone in patients with recurrent glioma. The recommended phase II dose of sorafenib is 200 mg twice daily when combined with temozolomide and radiation and 400 mg with radiation alone. To our knowledge, this is the first publication of concurrent sorafenib with radiation monotherapy or combined with radiation and temozolomide.

Integration method of 3D MR spectroscopy into treatment planning system for glioblastoma IMRT dose painting with integrated simultaneous boost

Background

To integrate 3D MR spectroscopy imaging (MRSI) in the treatment planning system (TPS) for glioblastoma dose painting to guide simultaneous integrated boost (SIB) in intensity-modulated radiation therapy (IMRT).

Methods

For sixteen glioblastoma patients, we have simulated three types of dosimetry plans, one conventional plan of 60-Gy in 3D conformational radiotherapy (3D-CRT), one 60-Gy plan in IMRT and one 72-Gy plan in SIB-IMRT. All sixteen MRSI metabolic maps were integrated into TPS, using normalization with color-space conversion and threshold-based segmentation. The fusion between the metabolic maps and the planning CT scans were assessed. Dosimetry comparisons were performed between the different plans of 60-Gy 3D-CRT, 60-Gy IMRT and 72-Gy SIB-IMRT, the last plan was targeted on MRSI abnormalities and contrast enhancement (CE).

Results

Fusion assessment was performed for 160 transformations. It resulted in maximum differences <1.00 mm for translation parameters and ≤1.15° for rotation. Dosimetry plans of 72-Gy SIB-IMRT and 60-Gy IMRT showed a significantly decreased maximum dose to the brainstem (44.00 and 44.30 vs. 57.01 Gy) and decreased high dose-volumes to normal brain (19 and 20 vs. 23% and 7 and 7 vs. 12%) compared to 60-Gy 3D-CRT (p < 0.05).

Conclusions

Delivering standard doses to conventional target and higher doses to new target volumes characterized by MRSI and CE is now possible and does not increase dose to organs at risk. MRSI and CE abnormalities are now integrated for glioblastoma SIB-IMRT, concomitant with temozolomide, in an ongoing multi-institutional phase-III clinical trial. Our method of MR spectroscopy maps integration to TPS is robust and reliable; integration to neuronavigation systems with this method could also improve glioblastoma resection or guide biopsies.

Evaluating changes in radiation treatment volumes from post-operative to same-day planning MRI in High-grade gliomas

Background

Adjuvant radiation therapy (RT) with temozolomide (TMZ) is standard of care for high grade gliomas (HGG) patients. RT is commonly started 3 to 5 weeks after surgery. The deformation of the tumor bed and brain from surgery to RT is poorly studied. This study examined the magnitude of volume change in the postoperative tumor bed and the potential impact of RT planning.

Method and materials

This study includes 24 patients with HGG who underwent craniotomy and adjuvant RT with TMZ at our institution. All patients had immediate postoperative MRI and repeat MRI during the day of RT simulation. Gross tumor volumes (GTV), clinical target volumes (CTV) of initial 46 Gy (CTV1) and boost to 60 Gy (CTV2) were contoured on both sets of MRIs according to RTOG (Radiation Therapy Oncology Group) guidelines. For patients who recurred after RT, the recurrence pattern was evaluated.

Results

An average of 17 days elapsed between immediate and delayed MRIs. GTV1 (FLAIR abnormality and tumor bed) decreased significantly on the delayed MRI as compared to immediate post-operative MRI (mean = 30.96cc, p = 0.0005), while GTV2 (contrast-enhanced T1 abnormality and tumor bed) underwent a non-significant increase (mean = 6.82cc, p = 0.07). Such changes lead to significant decrease of CTV1 (mean decrease is 113.9cc, p<0.01), and significant increase of CTV2 (mean increase is 32.5cc, p=0.05). At a median follow-up of 13 months, 16 patients (67%) progressed, recurred, or died, with a progression-free survival time of 13.7 months. Twelve patients failed within all CTVs based on immediate and delayed MRIs, while one patient recurred outside of CTV2 based on immediate post-operative MRI, but within the CTV2 defined on delayed MRI.

Conclusion

The postoperative tumor bed of HGGs undergoes substantial volumetric changes after surgery. Treatment planning based on delayed MRI significantly reduces the volume of treated brain tissue without local control detriment. The marked reduction of volume treated to 46 Gy based on delayed MRI scan, could result in increased sparing of organs at risk. There may be a small risk of inadequate radiation field design if radiation planning is based on immediate post-operative MRI.

Hypofractionated radiotherapy for glioblastoma: strategy for poor-risk patients or hope for the future?

The prognosis of patients with glioblastoma (GBM) remains poor, and the use of hyperfractionation or dose escalation beyond 60 Gy has not conferred any survival benefit. More recently, hypofractionated radiotherapy (HFRT) has been employed as a novel approach for achieving dose escalation, with interesting results. We present here a systematic overview of the role and development of HFRT as a possible therapeutic strategy in patients with GBM. We searched the PubMed database for studies published since 1990 that reported on the tolerance, safety and survival outcomes after HFRT. These studies reported on the paradox of improved survival in patients developing central radionecrosis within the high-dose volume. Most series reported no significant increase in early or late toxicity, except for one study that reported visual loss in one patient at 7 months after treatment. More recently, studies of HFRT combined with concurrent temozolomide (TMZ) reported a trend towards improved survival compared with historical controls, with a few studies reporting a median survival of approximately 20 months. The interpretation of data from the above studies is limited by the heterogeneities of patient population and the significant variation in the range of employed dose schedules. However, high-dose HFRT using intensity-modulated radiotherapy appears to be a safe and feasible therapeutic option. There is a suggestion of improved outcomes on combining HFRT with TMZ, which warrants further investigation in a randomised trial.