Hyperfractionated radiation therapy and bis-chlorethyl nitrosourea in the treatment of malignant glioma--possible advantage observed at 72.0 Gy in 1.2 Gy B.I.D. fractions: report of the Radiation Therapy Oncology Group Protocol 8302

Radiosensitization of IDH-Mutated Gliomas through ZMYND8 - a Pathway to Improved Outcomes

Isocitrate dehydrogenase 1-mutant (IDH1m) gliomas are recalcitrant tumors for which radiotherapy remains a standard treatment. A recent study identified ZMYND8 as a key mediator of radioresistance for IDH1m gliomas, and pharmacologic targeting of this pathway may heighten radiotherapy-induced tumor response, providing a prospect of improved clinical outcomes. See related article by Carney et al., p. 1763.

Gene Therapy for High Grade Glioma: The Clinical Experience

INTRODUCTION

High-grade gliomas (HGG) are the most common malignant primary brain tumors in adults, with a median survival of ~18 months. The standard of care (SOC) is maximal safe surgical resection, and radiation therapy with concurrent and adjuvant temozolomide. This protocol remains unchanged since 2005, even though HGG median survival has marginally improved.

AREAS COVERED

Gene therapy was developed as a promising approach to treat HGG. Here, we review completed and ongoing clinical trials employing viral and non-viral vectors for adult and pediatric HGG, as well as the key supporting preclinical data.

EXPERT OPINION

These therapies have proven safe, and pre- and post-treatment tissue analyses demonstrated tumor cell lysis, increased immune cell infiltration, and increased systemic immune function. Although viral therapy in clinical trials has not yet significantly extended the survival of HGG, promising strategies are being tested. Oncolytic HSV vectors have shown promising results for both adult and pediatric HGG. A recently published study demonstrated that HG47Δ improved survival in recurrent HGG. Likewise, PVSRIPO has shown survival improvement compared to historical controls. It is likely that further analysis of these trials will stimulate the development of new administration protocols, and new therapeutic combinations that will improve HGG prognosis.

A new approach to delineating clinical target volume for radiotherapy of glioblastoma: A phase II trial

Purpose

No consensus has currently been reached regarding the optimal radiation volume for radiotherapy of glioblastoma. Here, we have proposed a new delineation approach to delineating clinical target volume based on the relationship between the growth patterns of glioblastoma and neural pathways. Its safety and efficacy were evaluated in a phase II clinical trial.

Methods

A total of 69 patients with histologically confirmed glioblastoma were enrolled. All patients underwent tumor resection, followed by focal radiotherapy and concomitant temozolomide (TMZ), and then received six cycles of adjuvant TMZ. The gross tumor volume (GTV) was defined as the surgical resection cavity plus any residual enhancing tumor, on contrast enhanced T1-weighted MRI. The clinical target volume (CTV) was delineated through our new approach.

Results

The median recurrence-free survival (RFS) and overall survival (OS) were 11.4 months and 18.2 months, which were better than the previous reports. Relapse was found in 47 patients, of whom 41 patients (87.2%) failed in central, two patients (4.3%) failed in field, and four patients (8.5%) failed in distance. No marginal recurrence was found. Our regimen showed a trend of lower rates of marginal recurrence, and the brain volume of high-dose radiation fields in our regimen was similar to that of EORTC (p = 0.257).

Conclusions

We have proposed a novel method for the delineation of clinical target volume by referencing the nerve fiber bundles for radiotherapy of glioblastoma. The results of the present phase II clinical trial suggest that this approach may be feasible and effective.

The Definition and Delineation of the Target Area of Radiotherapy Based on the Recurrence Pattern of Glioblastoma After Temozolomide Chemoradiotherapy

Radiotherapy is an important treatment for glioblastoma (GBM), but there is no consensus on the target delineation for GBM radiotherapy. The Radiation Therapy Oncology Group (RTOG) and European Organisation for Research and Treatment of Cancer (EORTC) each have their own rules. Our center adopted a target volume delineation plan based on our previous studies. This study focuses on the recurrence pattern of GBM patients whose target delineations did not intentionally include the T2/fluid-attenuated inversion recovery (FLAIR) hyperintensity area outside of the gross tumor volume (GTV). We prospectively collected 162 GBM cases and retrospectively analysed the clinical data and continuous dynamic magnetic resonance images (MRI) of 55 patients with recurrent GBM. All patients received concurrent radiotherapy and chemotherapy with temozolomide (TMZ). The GTV that we defined includes the postoperative T1-weighted MRI enhancement area and resection cavity. Clinical target volume 1 (CTV1) and CTV2 were defined as GTVs with 1 and 2 cm margins, respectively. Planning target volume 1 (PTV1) and PTV2 were defined as CTV1 and CTV2 plus a 3 mm margin with prescribed doses of 60 and 54 Gy, respectively. The first recurrent contrast-enhanced T1-weighted MRI was introduced into the Varian Eclipse radiotherapy planning system and fused with the original planning computed tomography (CT) images to determine the recurrence pattern. The median follow-up time was 15.8 months. The median overall survival (OS) and progression-free survival (PFS) were 17.7 and 7.0 months, respectively. Among the patients, 44 had central recurrences, two had in-field recurrences, one had marginal recurrence occurred, 11 had distant recurrences, and three had subependymal recurrences. Five patients had multiple recurrence patterns. Compared to the EORTC protocol, target delineation that excludes the adjacent T2/FLAIR hyperintensity area reduces the brain volume exposed to high-dose radiation (P = 0.000) without an increased risk of marginal recurrence. Therefore, it is worthwhile to conduct a clinical trial investigating the feasibility of intentionally not including the T2/FLAIR hyperintensity region outside of the GTV.

Clinical Results of Unconventional Fractionation Radiotherapy in Central Nervous System Tumors

Malignant brain tumors (primary and metastatic) are apparently resistant to most therapeutic efforts. Several randomized trials have provided evidence supporting the efficacy of radiation therapy. Attempts at improving the results of external beam radiotherapy include altered fractionation, radiation sensitizers and concomitant chemotherapy. In low-grade gliomas, all clinical studies with radiotherapy have employed conventional dose fractionation regimens. In high-grade gliomas, hypofractionation schedules represent effective palliative regimens in poor prognosis subsets of patients; short-term survival in these patients has not allowed to evaluate late toxicity. In tumors arising within the central nervous system, hyperfractionated irradiation exploits the differences in repair capacity between tumour and late responding normal tissues. It may allow for higher total dose and may result in increased tumor cell kill. Accelerated radiotherapy may reduce the repopulation of tumor cells between fractions. It may potentially improve tumor control for a given dose level, provided that there is no increase in late normal tissue injury. In supratentorial malignant gliomas, superiority of accelerated hyperfractionated over conventionally fractionated schedules was observed in a randomized trial; however, the gain in survival was less than 6 months. At present no other randomized trial supports the preferential choice for altered fractionation irradiation. Also in pediatric brainstem tumors there are no data to confirm the routine use of hyperfractionated irradiation, and significant late sequelae have been reported in the few long-term survivors. Shorter treatment courses with accelerated hyperfractionated radiotherapy may represent a useful alternative to conventional irradiation for the palliation of brain metastases. Different considerations have been proposed to explain this gap between theory and clinical data. Patients included in dose/effect studies are not stratified by prognostic factors and other treatment-related parameters. This observation precludes any definite conclusion about the relative role of conventional and of altered fractionation. New approaches are currently in progress. More prolonged radiation treatments, up to higher total doses, could delay time to tumor progression and improve survival in good prognosis subsets of patients; altered fractionation may be an effective therapeutic tool to achieve this goal.

NRG oncology RTOG 9006: a phase III randomized trial of hyperfractionated radiotherapy (RT) and BCNU versus standard RT and BCNU for malignant glioma patients

From 1990 to 1994, patients with newly diagnosed malignant gliomas were enrolled and randomized between hyperfractionated radiation (HFX) of 72.0 Gy in 60 fractions given twice daily and 60.0 Gy in 30 fractions given once daily. All patients received 80 mg/m² of 1,3 bis(2 chloroethyl)-1 nitrosourea on days 1-3 q8 weeks for 1 year. Patients were stratified by age, KPS, and histology. The primary endpoint was overall survival (OS), with secondary endpoints including progression-free survival (PFS) and toxicity. Out of the 712 patients accrued, 694 (97.5%) were analyzable cases (350 HFX, 344 standard arm). There was no significant difference between the arms on overall acute or late treatment-related toxicity. No statistically significant effect for HFX, as compared to standard therapy, was found on either OS, with a median survival time (MST) of 11.3 versus 13.1 months (p = 0.20) or PFS, with a median PFS time of 5.7 versus 6.9 months (p = 0.18). The treatment effect on OS remained insignificant based on the multivariate analysis (hazard ratio 1.16; p = 0.0682). When OS was analyzed by histology subgroup there was also no significant difference between the two arms for patients with glioblastoma multiforme (MST: 10.3 vs. 11.2 months; p = 0.34), anaplastic astrocytoma (MST: 69.8 vs. 50.0 months; p = 0.91) or anaplastic oligodendroglioma (MST: 92.1 vs. 66.5 months; p = 0.33). Though this trial provided many invaluable secondary analyses, there was no trend or indication of a benefit to HFX radiation to 72.0 Gy in any subset of malignant glioma patients.

[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.

Three-Dimensional Conformal Radiotherapy, Temozolomide Chemotherapy, and High-Dose Fractionated Stereotactic Boost in a Protocol-Driven, Postoperative Treatment Schedule for High-Grade Gliomas

Aims and background

No available scientific report deals with high-dose (≥70 Gy) radiotherapy plus temozolomide chemotherapy (TMZ CHT) in high-grade gliomas. The survival results of a protocol-driven, postoperative treatment schedule are reported here to contribute to the discussion on this issue.

Methods and study design

Uniform criteria were prospectively adopted for case selection during the period 1993–2006 in the management of 123 patients, and we progressively introduced three-dimensional conformal radiotherapy (3D-CRT, 60 Gy), TMZ CHT and a high-dose (70 Gy) stereotactic boost (HDSRT) in the treatment schedule. Palliative radiotherapy was delivered by whole brain irradiation (WBI, 50 Gy) for bulky tumors, whereas radical irradiation was performed with 3D-CRT throughout the study period. Two periods of accrual are considered: 36 patients were treated before 31 December 1999 (29.25%) and 87 (70.75%) after 1 January 2000. This subdivision was due to the implementation of HDSRT hardware and TMZ CHT from January 2000.

Results

The median overall survival was 13 months and the 1-, 2- and 3-year survival rates were 53%, 19.5% and 11.6%, respectively. The differences in survival related to the treatment variables were highly significant, both in univariate and multivariate analysis. The median survival and 1-, 2- and 3-year survival rates in the palliative WBI group were 9.75 months and 37%, 2%, and 0%, respectively; in the 3D-CRT group 17.25 months and 64%, 34%, and 15%, respectively; in the TMZ CHT concomitant with radiotherapy group 20 months and 61%, 39%, and 21%, respectively; in the TMZ CHT concomitant with and sequential to radiotherapy group 25.75 months and 84%, 54%, and 26%, respectively, and in the HDSRT group 22 months and 72%, 48%, and 37%, respectively. No symptomatic radiation necrosis occurred in any of the groups.

Conclusions

The results reported here are generally better than those reported in the literature. The selection of patients on the basis of favorable prognostic factors and suitability to the currently available, aggressive postoperative treatment resources can be the mainstay for improving therapeutic results. In particular, the new treatment option reported here (HDSRT in association with TMZ CHT) proved to be safe and effective in obtaining a relatively favorable outcome.

Management of GBM: a problem of local recurrence

Forty years ago, adjuvant treatment of patients with GBM using fractionated radiotherapy following surgery was shown to substantially improve survival compared to surgery alone. However, even with the addition of temozolomide to radiotherapy, overall survival is quite limited and local failure remains a fundamental problem, despite multiple attempts to increase dose to the tumor target. This review presents the historical background and clinical rationale leading to the current standard of care consisting of 60 Gy total dose in 2 Gy fractions to the MRI-defined targets in younger, high performance status patients and more hypofractionated regimens in elderly and/or debilitated patients. Particle therapies offer the potential to increase local control while reducing dose and, potentially, long-term neurocognitive toxicity. However, improvements in systemic therapies for GBM will need to be implemented before the full benefits of improved local control can be realized.

[Guidelines for the radiotherapy of gliomas]

Gliomas are the most frequent primary brain tumours. Treating these tumours is difficult because of the proximity of organs at risk, infiltrating nature, and radioresistance. Clinical prognostic factors such as age, Karnofsky performance status, tumour location, and treatments such as surgery, radiation therapy, and chemotherapy have long been recognized in the management of patients with gliomas. Molecular biomarkers are increasingly evolving as additional factors that facilitate diagnosis and therapeutic decision-making. These practice guidelines aim at helping in choosing the best treatment, in particular radiation therapy.

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.

Standardization and quality assurance of radiation therapy volumes for adults with high-grade gliomas

Standard treatment for Glioblastoma Multiforme (GBM) consists of a combination of chemotherapy and radiation therapy followed by adjuvant chemotherapy. While the optimal dose of radiation therapy has been established, significant variability in volume of tissue irradiated exists. In this article we review the current guidelines, patterns of care, patterns of failure, imaging advances and toxicity related to radiation therapy volumes in the treatment of GBM.

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.

(18)F-Fluorothymidine PET-CT for resected malignant gliomas before radiotherapy: tumor extent according to proliferative activity compared with MRI

OBJECTIVE

To compare the presence of post-operative residual disease by magnetic resonance imaging (MRI) and [18F]fluorothymidine (FLT)-positron emission tomography (PET)-computer tomography (CT) in patients with malignant glioma and to estimate the impact of 18F-FLT PET on the delineation of post-operative target volumes for radiotherapy (RT) planning.

METHODS

Nineteen patients with post-operative residual malignant gliomas were enrolled in this study. For each patient, 18F- FLT PET-CT and MRI were acquired in the same week, within 4 weeks after surgery but before the initiation of RT. The PET-CT and MRI data were co-registered based on mutual information. The residual tumor volume defined on the 18F-FLT PET (Vol-PET) was compared with that of gadolinium [Gd] enhancement on T1-weighted MRI (Vol-T1) and areas of hyperintensity on T2-weighted MRI (Vol-T2).

RESULTS

The mean Vol-PET (14.61 cm3) and Vol-T1 (13.60 cm3) were comparable and smaller than the mean Vol-T2 (32.93 cm3). The regions of 18F-FLT uptake exceeded the contrast enhancement and the hyperintense area on the MRI in 14 (73.68%) and 8 patients (42.11%), respectively. In 5 (26.32%) of the 19 patients, Vol-PET extended beyond 25 mm from the margin of Vol-T1; in 2 (10.53%) patients, Vol-PET extended 20 mm from the margin of Vol-T2. Vol-PET was detected up to 35 mm away from the edge of Vol-T1 and 24 mm away from the edge of Vol-T2. In 16 (84.21%) of the 19 patients, the Vol-T1 extended beyond the Vol-PET. In all of the patients, at least some of the Vol-T2 was located outside of the Vol-PET.

CONCLUSIONS

The volumes of post-operative residual tumor in patients with malignant glioma defined by 18F-FLT uptake on PET are not always consistent with the abnormalities shown on post-operative MRI. Incorporation of 18F-FLT-PET in tumor delineation may have the potential to improve the definition of target volume in post-operative radiotherapy.

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.

Interfractional variation of radiation target and adaptive radiotherapy for totally resected glioblastoma

This study aimed to evaluate the effects of volume adapted re-planning for radiotherapy (RT) after gross total resection (GTR) for glioblastoma. Nineteen patients with glioblastoma who underwent GTR and postoperative RT were analyzed. The volumes of the surgical cavity on computed tomography (CT) obtained one day after GTR (CT0), the first RT simulation CT (sim-CT1), and the second simulation CT for the boost RT plan (sim-CT2) were compared. The boost RT plan was based on the surgical cavity observed on the sim-CT2 (boost RTP2) and was compared with that based on the surgical cavity observed on the sim-CT1 (boost RTP1). The volume reduction ratios were 14.4%-51.3% (median, 29.0%) between CT0 and sim-CT1 and -7.9%-71.9% (median, 34.9%) between sim-CT1 and sim-CT2 (P < 0.001). The normal brain volumes in boost RTP1 were significantly reduced in boost RTP2, especially at high dose levels. Target volume in sim-CT2 which was not covered with the boost RTP1, developed in five cases (26.3%). The surgical cavity volume was reduced following surgery in patients with glioblastoma who underwent GTR. The application of volume-adapted re-planning during RT could decrease the irradiated volume of normal brain and prevent a target miss for boost RT.

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.

Current challenges in clinical target volume definition: tumour margins and microscopic extensions

Determination of optimal clinical target volume (CTV) margins around gross tumour volume (GTV) for modern radiotherapy techniques, requiring more precise target definitions, is controversial and complex. Tumour localisation has been greatly improved using molecular imaging integrated with conventional imaging techniques. However, the exact incidence and extent of microscopic disease, to be encompassed by CTV, cannot be visualised by any techniques developed to date and remain uncertain. As a result, the CTV is generally determined by clinicians based on their experience and patients' histopathological data. In this article we review histopathological studies addressing the extent of subclinical disease and its possible correlation with tumour characteristics in various tumour sites. The data have been tabulated to facilitate a comparison between proposed margins by different investigations and with current margins generally accepted for each tumour site. It is concluded that there is a need for further studies to reach a consensus on the optimal CTV pertaining to each tumour site.

Advances in radiotherapy of brain tumors: radiobiology versus reality

Radiotherapy still remains the most effective adjunctive therapy for malignant gliomas following surgery and provides useful local control for some benign tumors. Research efforts have been directed towards several aspects of the radiation therapy of tumors. The results of clinical trials undertaken in the last decade offer some basis for optimism in the management of patients with malignant brain tumors, although cure is still not a realistic objective. This review focuses on the rationale and radiobiological basis for recent developments in the radiotherapy of adult brain tumors. The salient issues are discussed from a neurosurgeon's perspective.

Anaplastic gliomas: radiation, chemotherapy, or both?

The optimal treatment of anaplastic gliomas is controversial. Options for treatment include radiation, chemotherapy or a combination of modalities. This article describes how treatment algorithms for anaplastic gliomas have evolved and interprets the results of recent studies. The available evidence indicates that patients can be treated with either chemotherapy or radiation as initial therapy, with use of the other treatment modality at relapse. Whether subpopulations exist for whom one treatment modality is superior to the other at initial diagnosis must be studied prospectively.

Radiotherapy and temozolomide for newly diagnosed glioblastoma and anaplastic astrocytoma: validation of Radiation Therapy Oncology Group-Recursive Partitioning Analysis in the IMRT and temozolomide era

Since the development of the Radiation Therapy Oncology Group-Recursive Partitioning Analysis (RTOG-RPA) risk classes for high-grade glioma, radiation therapy in combination with temozolomide (TMZ) has become standard care. While this combination has improved survival, the prognosis remains poor in the majority of patients. Therefore, strong interest in high-grade gliomas from basic research to clinical trials persists. We sought to evaluate whether the current RTOG-RPA retains prognostic significance in the TMZ era or alternatively, if modifications better prognosticate the optimal selection of patients with similar baseline prognosis for future clinical protocols. The records of 159 patients with newly-diagnosed glioblastoma (GBM, WHO grade IV) or anaplastic astrocytoma (AA, WHO grade III) were reviewed. Patients were treated with intensity-modulated radiation therapy (IMRT) and concurrent followed by adjuvant TMZ (n = 154) or adjuvant TMZ only (n = 5). The primary endpoint was overall survival. Three separate analyses were performed: (1) application of RTOG-RPA to the study cohort and calculation of subsequent survival curves, (2) fit a new tree model with the same predictors in RTOG-RPA, and (3) fit a new tree model with an expanded predictor set. All analyses used a regression tree analysis with a survival outcome fit to formulate new risk classes. Overall median survival was 14.9 months. Using the RTOG-RPA, the six classes retained their relative prognostic significance and overall ordering, with the corresponding survival distributions significantly different from each other (P < 0.01, χ² statistic = 70). New recursive partitioning limited to the predictors in RTOG-RPA defined four risk groups based on Karnofsky Performance Status (KPS), histology, age, length of neurologic symptoms, and mental status. Analysis across the expanded predictors defined six risk classes, including the same five variables plus tumor location, tobacco use, and hospitalization during radiation therapy. Patients with excellent functional status, AA, and frontal lobe tumors had the best prognosis. For patients with newly-diagnosed high-grade gliomas, RTOG-RPA classes retained prognostic significance in patients treated with TMZ and IMRT. In contrast to RTOG-RPA, in our modified RPA model, KPS rather than age represented the initial split. New recursive partitioning identified potential modifications to RTOG-RPA that should be further explored with a larger data set.

A treatment planning study on glioblastoma with different techniques using boron neutron capture therapy, 3-dimensional conformal radiotherapy, and intensity modulated radiotherapy

To propose adequate indices predicting efficacy of boron neutron capture therapy (BNCT) for glioblastoma, a comparative treatment planning study between BNCT, 3-dimensional conformal radiotherapy (3D-CRT), and intensity-modulated radiotherapy (IMRT) was performed, and dose-volume histograms (DVHs) on planning target volume (PTV) and normal brain were calculated. Therapeutic benefit of BNCT was quantitatively evaluated using conformity indices, which have been previously suggested by radiation therapy oncology group (RTOG) and Saint-Anne, Lariboisière, Tenon (SALT). Although dose homogeneities from the BNCT plans were poor than the other modalities due to simple irradiation fields, lesion coverage factor, CVF, from the BNCT plans were comparable to those from the 3D-CRT and IMRT plans (median values, 0.991, 0.989, and 0.961, respectively). The geometrical factors, g, from the BNCT plans, which describes target volumes receiving doses under the prescribed doses and normal brain volume covered by the prescribed doses, were lowest compared to those for the other modalities (median values, 0.009, 0.115, and 0.043). For the BNCT plans, maximum dose escalation up to 2.080 times the prescribed dose was possible without exceeding normal brain tolerance dose. As the indices can evaluate the quantitative benefit of BNCT and maximum dose escalation for the individual patient, it is expected that the indices can effectively evaluate the treatment plan of BNCT.

Stereotactic radiosurgery for glioblastoma: retrospective analysis

Purpose

This retrospective study was done to better understand the conditions for which stereotactic radiosurgery (SRS) for glioblastoma may be efficacious.

Methods

Between 2000 and 2007, 33 patients with a pathological diagnosis of glioblastoma received SRS with the Novalis^® Shaped Beam Radiosurgery system. Eighteen patients (54%) underwent salvage SRS for recurrence while 15 (45%) patients received upfront SRS following standard fractionated RT for newly diagnosed glioblastoma.

Results

There were no RTOG grade >2 acute side effects. The median survival after SRS was 6.7 months (range 1.4 – 74.7). There was no significant difference in overall survival (from the time of initial diagnosis) with respect to the timing of SRS (p = 0.2). There was significantly better progression free survival in patients treated with SRS as consolidation versus at the time of recurrence (p = 0.04). The majority of patients failed within or at the margin of the SRS treatment volume (21/26 evaluable for recurrence).

Conclusion

SRS is well tolerated in the treatment of glioblastoma. As there was no difference in survival whether SRS is delivered upfront or at recurrence, the treatment for each patient should be individualized. Future studies are needed to identify patients most likely to respond to SRS.

Optimizing radiotherapy schedules for elderly glioblastoma multiforme patients

Glioblastoma is the most common malignant primary brain tumor. Despite recent advances, the overall prognosis remains poor with median survivals of approximately 1 year and 5-year survivals of less than 5%. Efforts at risk stratification have identified age and performance status as the most important prognostic features. It is well established that patients treated with postoperative radiation therapy have improved survival and functional capacity compared with unirradiated patients. Recent evidence suggests that the benefit of postoperative radiation persists even within the cohort aged 70 years or over. Some investigators have questioned whether the standard treatment schedule of 60 Gy delivered over a 6-week period is necessary for older patients with limited functional status. Alternative treatment schedules have been devised to reduce the inconvenience and morbidity of standard therapy. This review aims to evaluate the current state of knowledge on alternative radiotherapy schedules for elderly and poor-prognosis patients with glioblastoma.

Prospective single-arm study of 72 Gy hyperfractionated radiation therapy and combination chemotherapy for anaplastic astrocytomas

Background

Despite intensive multimodal treatment, outcome of patients with malignant glioma remains poor, and a standard dose of radiotherapy for anaplastic astrocytoma has not been defined. In the past RTOG study (83-02), the arm of 72 Gy hyperfractionated radiotherapy (HFRT) for malignant gliomas showed better outcome than the arms of higher doses (76.8 – 81.6 Gy) and the arms of lower doses (48 – 54.4 Gy). The purpose of this study is to verify the efficacy of this protocol.

Methods

From July 1995, 44 consecutive eligible patients with histologically proven anaplastic astrocytoma were enrolled in this study (HFRT group). The standard regimen in this protocol was post-operative radiotherapy of 72 Gy in 60 fractions (1.2 Gy/fraction, 2 fractions/day) with concurrent chemotherapy (weekly ACNU). The primary endpoint was local control rate (LCR), and the secondary endpoints were overall survival (OS), progression-free survival (PFS) and late toxicity.

Results

Three-year OS of the HFRT group was 64.8% (95% confidence interval; 48.4–81.3%). Three-year PFS rate and LCR were 64.4% (95%CI: 48.4–80.3%) and 81.6% (95%CI: 69.2–94.8%), respectively.

The number of failures at 5 years in the HFRT group were 14 (32%). The number of failures inside the irradiation field was only about half (50%) of all failures. One (2%) of the patients clinically diagnosed as brain necrosis due to radiation therapy.

Conclusion

The results of this study suggested that 72 Gy HFRT seemed to show favorable outcome for patients with anaplastic astrocytoma with tolerable toxicity.

Mathematical modeling of brain tumors: effects of radiotherapy and chemotherapy

Gliomas, the most common primary brain tumors, are diffusive and highly invasive. The standard treatment for brain tumors consists of a combination of surgery, radiation therapy and chemotherapy. Over the past few years, mathematical models have been applied to study untreated and treated brain tumors. In an effort to improve treatment strategies, we consider a simple spatio-temporal mathematical model, based on proliferation and diffusion, that incorporates the effects of radiotherapeutic and chemotherapeutic treatments. We study the effects of different schedules of radiation therapy, including fractionated and hyperfractionated external beam radiotherapy, using a generalized linear quadratic (LQ) model. The results are compared with published clinical data. We also discuss the results for combination therapy (radiotherapy plus temozolomide, a new chemotherapy agent), as proposed in recent clinical trials. We use the model to predict optimal sequencing of the postoperative (combination of radiotherapy and adjuvant, neo-adjuvant or concurrent chemotherapy) treatments for brain tumors.

Evaluation of Peritumoral Edema in the Delineation of Radiotherapy Clinical Target Volumes for Glioblastoma

PURPOSE

To evaluate the spatial relationship between peritumoral edema and recurrence pattern in patients with glioblastoma (GBM).

METHODS AND MATERIALS

Forty-eight primary GBM patients received three-dimensional conformal radiotherapy that did not intentionally include peritumoral edema within the clinical target volume between July 2000 and June 2001. All 48 patients have subsequently recurred, and their original treatment planning parameters were used for this study. New theoretical radiation treatment plans were created for the same 48 patients, based on Radiation Therapy Oncology Group (RTOG) target delineation guidelines that specify inclusion of peritumoral edema. Target volume and recurrent tumor coverage, as well as percent volume of normal brain irradiated, were assessed for both methods of target delineation using dose-volume histograms.

RESULTS

A comparison between the location of recurrent tumor and peritumoral edema volumes from all 48 cases failed to show correlation by linear regression modeling (r(2) = 0.0007; p = 0.3). For patients with edema >75 cm(3), the percent volume of brain irradiated to 46 Gy was significantly greater in treatment plans that intentionally included peritumoral edema compared with those that did not (38% vs. 31%; p = 0.003). The pattern of failure was identical between the two sets of plans (40 central, 3 in-field, 3 marginal, and 2 distant recurrence).

CONCLUSION

Clinical target volume delineation based on a 2-cm margin rather than on peritumoral edema did not seem to alter the central pattern of failure for patients with GBM. For patients with peritumoral edema >75 cm(3), using a constant 2-cm margin resulted in a smaller median percent volume of brain being irradiated to 30 Gy, 46 Gy, and 50 Gy compared with corresponding theoretical RTOG plans that deliberately included peritumoral edema.

Treatments for astrocytic tumors in children: current and emerging strategies

Strategies for the treatment of childhood cancer have changed considerably during the last 50 years and have led to dramatic improvements in long-term survival. Despite these accomplishments, CNS tumors remain the leading cause of death in pediatric oncology. Astrocytic tumors form the most common histologic group among childhood brain tumors. They are a heterogeneous group that from a practical therapeutic point of view can be subdivided into low-grade astrocytomas (LGA), optic pathway gliomas (OPG), high-grade astrocytomas (HGA), and brainstem gliomas (BSG). This article focuses on the practical application of treatments that lead to long-term survival, improved quality of life, and reduced long-term complications. Improvement in therapy has led to better outcomes for patients with LGA and OPG. Careful follow-up without any treatment is indicated for a small percentage of patients diagnosed with LGA with an indolent course including children with neurofibromatosis type 1 (NF1). Surgery is the main recommended treatment for children with resectable LGA. Radiation therapy is generally recommended for children with progressive LGA, or after failure of chemotherapy, accomplishing tumor control at 10 years in over 60% of patients. Cytotoxic chemotherapy is usually reserved for children who have had treatment failure with surgery and radiation therapy. It is also offered for children who are too young to be treated with radiation or to defer or avoid radiotherapy. Carboplatin and vincristine achieve 5% complete and 28% partial responses but the use of vincristine is criticized due to poor penetration of the CNS. A regimen of tioguanine, procarbazine, mitolactol, lomustine, and vincristine is frequently administered as an alternative to carboplatin and vincristine in LGA. The introduction of temozolomide has allowed better responses, including a 24% complete response rate compared with 0-5% complete response rates with the previous regimens. OPG are usually histologically LGA, and are treated with similar chemotherapy regimens. OPG is the most common type of brain tumor associated with NF1. Tumor growth in some of these patients is slow with no treatment recommended for an extended period of time. The prognosis for children with the remaining types of astrocytomas remains poor. Surgical resection is typically the first step in the treatment of HGA followed in older children by radiation therapy. The data regarding chemotherapy are mixed. Combination chemotherapy before or after radiation, including cisplatin, carmustine, cyclophosphamide, and vincristine or carboplatin, ifosfamide, cyclophosphamide, and etoposide has provided disappointing results. Clinical trials with temozolomide and agents directed against single targets have not shown substantially better results, but it is hoped that currently conducted studies will provide better outcomes. Diffuse intrinsic BSG are among the most difficult-to-treat brain tumors. Surgical treatment is not recommended for diffuse intrinsic BSG and standard radiation therapy is typically given in children aged >3 years. None of the numerous chemotherapy regimens, including temozolomide, has provided a significant response rate or an improvement in survival. It is expected that newer agents affecting multiple targets such as AEE-788 and antineoplastons, and combinations of single-targeted agents with chemotherapy will provide better results. Careful evaluation of histology, location of the tumor, patient age, and consideration of treatment-related morbidity play an important part in selecting between clinical observation, surgery, radiation, chemotherapy, or investigational agents. The goals of treatment for astrocytic tumors should extend well beyond objective responses and increased survival. Improvement of quality of life is an equally important objective of treatment. Radiation therapy and chemotherapy result in serious late toxicities.

Response of intracerebral human glioblastoma xenografts to multifraction radiation exposures

PURPOSE

We investigated the effects of fractionated radiation treatments on the life spans of athymic rats bearing intracerebral brain tumors.

METHODS AND MATERIALS

U-251 MG or U-87 MG human glioblastoma cells were implanted into the brains of athymic rats, and the resulting tumors were irradiated once daily with various doses of ionizing radiation for 5 consecutive days or for 10 days with a 2-day break after Day 5.

RESULTS

Five daily doses of 1 and 1.5 Gy, and 10 doses of 0.75 and 1 Gy, cured some U-251 MG tumors. However, five daily doses of 0.5 Gy increased the survival time of animals bearing U-251 MG tumors 5 days without curing any animals of their tumors. Ten doses of 0.3 Gy given over 2 weeks extended the lifespan of the host animals 9 days without curing any animals. For U-87 MG tumors, 5 daily doses of 3 Gy produced an increased lifespan of 8 days without curing any animals, and 10 doses of 1 Gy prolonged lifespan 5.5 days without curing any animals. The differences in extension of life span between the 5- and 10-fraction protocols were minor for either tumor type.

CONCLUSION

The finding that the U-251 MG tumors are more sensitive than U-87 MG tumors, despite the fact that U-251 MG tumors contain many more hypoxic cells than U-87 MG tumors, suggests the intrinsic cellular radiosensitivities of these cell lines are more important than hypoxia in determining their in vivo radiosensitivities.

Current role of radiation therapy in the management of malignant brain tumors

The objective of this article is to explain how the current management of malignant brain tumors has evolved, using the foundation of evidence-based literature. Radiotherapy plays a central role in the multidisciplinary management of primary brain tumors and brain metastases. The techniques of radiotherapy continue to be refined to optimize local control while minimizing potential treatment-related neurocognitive toxicities.

Angiogenic patterns and their quantitation in high grade astrocytic tumors

BACKGROUND

The objectives of this study on high grade astrocytic tumors were (i) to establish differences, if any, between grades III & IV tumors among angiogenic parameters, both qualitative and quantitative, and (ii) to correlate angiogenic parameters with proliferation indices, namely T2a and MIB1 labeling indices.

DESIGN

Twenty nine consecutive cases of WHO grades III (11) and IV (18) astrocytic tumors diagnosed in the year-2004 were studied, using H&E and CD34, MIB1 and T2a immunostaining by streptavidin biotin technique. Angiogenic patterns were studied and parameters quantitated using Image Pro Plus software (four hotspots) on CD34 immunostained sections to determine intratumoral microvessel density (iMVD), microvascular area (MVA), aspect, mean diameter (MD) and fractal dimension (FD).

RESULTS

Main angiogenic patterns of capillary (18) and glomeruloid (9) types were best developed in glioblastomas. Statistically significant differences (P<0.05) were seen between grades III and IV in iMVD, aspect, MD and FD, but not in angiogenic patterns or MVA (P = 0.27). Statistically significant differences (P<0.05) were seen between glioblastomas with glomeruloid vs. capillary types in iMVD and FD, but not in MVA, aspect and mean vessel diameter. T2a values correlated with MIB1 labeling indices (R = 0.965, P<0.001). Intratumoral endothelial MIB1 LI was significantly higher in grade IV as compared to grade III, but did not correlate with angiogenic parameters. No correlation of angiogenic patterns and proliferation indices was noted (R = -0.221, P = 0.26). Limited follow up data showed all recurrent grade IV tumors to be of glomeruloid type.

CONCLUSION

Increased angiogenesis in grade IV, as compared to grade III, astrocytic tumors is characterized by an increased number/density of vessels: an increase in vessels characterized by disproportionate lengthening and likely associated with the infiltrative properties of the tumors; and an increase in pliable, irregularly shaped or structured vessels. In addition, there is a greater frequency of glomeruloid structures indicating inadequate directional migration of the newly formed vessels. The lack of correlation of these angiogenesis parameters with the MIB1 and T2a proliferation indices reflects the complexity of angiogenesis parameters in high grade gliomas. Further studies are needed to determine the usefulness of the angiogenic parameters in the improved diagnosis (grading) and prognosis of astrocytic tumors.

High-dose conformal radiotherapy for supratentorial malignant glioma: a historical comparison

BACKGROUND

Although radiotherapy remains the main postoperative treatment for patients with malignant glioma, modifications to regimens have not improved the poor outlook of patients with this disease. We aimed to investigate whether high-dose conformal radiotherapy improves the survival of patients with supratentorial malignant glioma compared with conventional radiotherapy.

METHODS

29 patients with anaplastic astrocytoma and 61 patients with glioblastoma who received high-dose conformal radiotherapy during 1990-2002 were compared with 34 patients with anaplastic astrocytoma and 60 patients with glioblastoma who received conventional 60 Gy radiotherapy during 1979-89. 77 of the 90 patients receiving high-dose radiotherapy were given 80 Gy; the remaining 13 patients, all with glioblastoma, received 90 Gy. Radiotherapy was planned on the basis of images taken before surgery, and doses were delivered in 2 Gy per fraction per day for 5 days a week. Hazard ratios for death were calculated with a Cox model, and were adjusted for age, Karnofsky performance scale, tumour size, and extent of resection.

FINDINGS

Patients who received high-dose radiotherapy had significantly longer overall survival compared with those who received conventional radiotherapy (adjusted hazard ratio 0.30 [95% CI 0.12-0.76], p=0.011 for anaplastic astrocytoma and 0.49 [0.28-0.87], p=0.014 for glioblastoma). Patients with anaplastic astrocytoma in the high-dose group have not yet reached median survival; median survival in the conventional radiotherapy group was 22.3 months (95% CI 20.6-24.0). 5-year survival was 51.3% (29.2-73.4) for the high-dose group and 14.7% (0.0-30.0) for the conventional group. Median survival in patients with glioblastoma was 16.2 months (12.8-19.6) for the high-dose group and 12.4 months (10.0-14.8) for the conventional group. 2-year survival was 38.4% (23.5-53.3) for the high-dose group and 11.4% (0.0-25.3) for the conventional group. Survival did not differ between those that received 80 Gy radiotherapy and those that received 90 Gy (hazard ratio 0.94 [95% CI 0.42-2.12]). The higher frequency of radiation-induced white matter abnormality in the high-dose group compared with the conventional radiotherapy group did not lead to increased disability.

INTERPRETATION

High-dose, standard-fractionated radiotherapy shows potential as the main postoperative treatment for patients with supratentorial malignant glioma.

Usefulness of L-[methyl-11C] methionine-positron emission tomography as a biological monitoring tool in the treatment of glioma

OBJECT

The authors retrospectively analyzed the data obtained in patients who had undergone L-[methyl-11C] methionine (MET)-positron emission tomography (PET) studies to clarify the relationship between MET uptake and tumor biological features and to discuss the clinical usefulness of MET-PET studies.

METHODS

One hundred ninety-four patients with cerebral glioma or suspected glioma underwent PET scanning 20 minutes after injection of MET, whose uptake into the tumor was expressed as a ratio to contralateral healthy brain tissue (T/N ratio). Analyses were performed to determine how MET uptake correlated with tumor pathological features and prognosis. The T/N ratios before and after various treatments were also examined. There were significant differences in the T/N ratio among the nonneoplastic lesions, low-grade gliomas, and malignant gliomas. Furthermore, there were significant correlations between patient survival and pretreatment T/N ratios. Among patients with malignant gliomas, a significant difference in survival was observed between cases with and without postoperative tumor remnant based on elevated MET uptake. The MET uptake was heterogeneous even among the homogeneous tumor areas demonstrated on MR imaging. Malignant pathological features were detected in the areas with the highest MET uptake. The effectiveness of radiotherapy or chemotherapy was expressed as a significantly decreased T/N ratio in some of the tumor types.

CONCLUSIONS

The ability of MET-PET to reflect the biological nature of gliomas makes it an excellent method for monitoring active tumor tissue, and treatments based on its findings should provide a powerful clinical protocol in the course of glioma therapy.

Establishment and characterization of a new human glioblastoma cell line, NYGM

A cell line designated NYGM was established from a human cerebral glioblastoma multiforme (GBM) obtained from a 75-year-old Japanese woman. The cell line has grown slowly without interruption and has been propagated continuously by serial passages (more than 80 passage) during the past 3 years. The cultured cells were fusiform or polyhedral in shape. The population doubling time was 24 hours. The chromosomal number varied between 77 and 88, with modal chromosomal number of 84. NYGM cells concomitantly expressed MET receptor tyrosine kinase (a product of c-met protooncogene) and its ligand HGF/SF (hepatocyte growth factor/scatter factor), as well as HGF activator and HGF activator inhibitors. The cells might be useful for the study of pericellular regulation of HGF/SF-MET signaling and HGF activation of GBM cells.

Dose-Escalated Conformal Radiotherapy of Glioblastomas – Results of a Retrospective Comparison Applying Radiation Doses of 60 and 70 Gy

BACKGROUND

Dose escalated three-dimensional conformal radiotherapy with 70 Gy against glioblastomas was compared retrospectively with the standard scheme of 60 Gy using 2-D-planning.

PATIENTS AND METHODS

In the period from 1994 to 1998, a series of 135 patients with glioblastomas was treated by surgery and postoperative radiotherapy. A conversion from 2-D into 3-D-planning was carried out in 4/1996. The prescribed total dose for the first 65 patients was 60 Gy (group 60). A boost up to 70 Gy was added for the remaining 70 patients (group 70).

RESULTS

The median survival time was 8.0 months for group 60 and 8.3 months for group 70. A dependency on the applied dose range was found. The median survival time was 3 months for patients who received a radiation dose of 55 Gy or less, 8.6 months for doses between 56 and 65 Gy, and 9.6 months for patients with a dose between 66 and 75 Gy (p < 0.01). In a multivariate analysis only the performance status maintained significance (p = 0.02) as a prognostic factor, while the dose range reached borderline significance (p = 0.09).

CONCLUSION

No statistically significant survival prolongation was reached despite a dose escalation to 70 Gy.

Interfraction interval in patients with stage III non-small-cell lung cancer treated with hyperfractionated radiation therapy with or without concurrent chemotherapy: final results in 536 patients

We investigated the influence of interfraction interval (IFI) on treatment outcome in patients with stage III non-small-cell lung cancer (NSCLC) treated with hyperfractionated radiation therapy (Hfx RT) with or without concurrent chemotherapy (CHT). During 3 randomized phase III and 1 phase II study, a total of 536 patients were treated with Hfx RT alone or with concurrent carboplatin/etoposide. Two hundred eighty-five patients were treated with IFI of 4.5-5.0 hours, while 251 patients were treated with IFI of 5.5-6.0 hours. "Shorter" (4.5-5.0 hours) IFI led to better overall survival (OS) (P = 0.0000) and local recurrence-free survival (LRFS) (P = 0.0000). Multivariate analyses showed IFI to be an independent prognosticator of both OS and LRFS. These results were confirmed when we separated all patients (n = 536) into those treated with Hfx RT only (n = 127) and those treated with concurrent RT/CHT (n = 409). Various RT-related high-grade acute toxicity was not different between the 2 IFI, but patients treated with shorter IFI had a significantly higher incidence of hematological toxicity (P = 0.002). None of the late high-grade toxicities were different between the 2 interfraction intervals. Using regression analysis, it was shown that IFI was not a significant predictor of any of acute or late high-grade (> or =3) toxicity. IFI is an important prognosticator of OS and LRFS in patients with stage III NSCLC treated with Hfx RT with or without concurrent carboplatin/etoposide. IFI led to higher incidence only of hematological toxicity, but was not predictive of any acute or late high-grade (> or =3) toxicity. A carefully designed randomized trial seems necessary to give better insight into the issue of optimal IFI in this disease.

Human interferon beta, nimustine hydrochloride, and radiation therapy in the treatment of newly diagnosed malignant astrocytomas

Previous investigators have reported encouraging results for malignant gliomas treated using a combination of human interferon beta (IFN-beta) with nimustine hydrochloride (ACNU) and radiation therapy (termed IAR therapy). This study was undertaken to examine further the efficacy of the IAR regimen followed by maintenance therapy with IFN-beta and ACNU in patients with newly diagnosed malignant astrocytomas. Fifty-eight patients were enrolled onto the trial. IFN-beta (2 x 10(6) IU/m(2)/day x 5 days/week for 8 consecutive weeks) and ACNU (80 mg/m(2) on days 1 and 36) were administered intravenously concomitant with radiation therapy followed by IFN-beta (every 2 weeks) and ACNU (every 6 weeks). Of 33 patients assessable for a response, 11 responded (33%), with 4 complete responses. The estimated median overall survival (OS) was 16 months, with values of 58 and 13 months for anaplastic astrocytoma (AA) and glioblastoma (GB) patients, respectively. The overall progression free survival (PFS) was 11 months, with values of 31 and 7 months for AA and GB patients, respectively. The IAR therapy was safe and well tolerated. Based on a statistical analysis of the factors that affected the PFS and OS, histologic grade, postoperative Karnofsky performance scale (KPS), and extent of surgery were identified as independent predictors. The postoperative KPS stood out as the most powerful prognostic factor, which was also the best predictor for the response to IAR therapy. Our findings suggest a possible benefit for IAR therapy followed by maintenance therapy mainly in AA. In addition, they emphasize the importance of a preserved KPS after cytoreductive surgery, which could produce a potential benefit for adjuvant therapy and could ultimately lead to a prolonged survival.

Clinical prognostic factors in patients with malignant glioma treated with combined modality approach

The impact of various clinical pretreatment prognostic factors in patients with malignant glioma treated with a combined modality approach was investigated in 229 patients treated on four consecutive prospective phase II studies. The median survival time for all 229 patients is 14 months, and 2- and 5-year survival rates are 34%, and 9%, respectively. The median time to tumor progression is 14 months, and 2- and 5-year progression-free survival rates are 32%, and 9%, respectively. Females did better than males, while patients 55 years or less did better than those more than 55 years. Patients with Karnofsky performance status (KPS) 80 to 100 did better than those with KPS 50 to 70 as well as did patients having preoperative tumor sizes 4 cm or less when compared to those with larger tumors. Frontal tumor location as well as more extensive surgery favorably influenced survival. Patients harboring anaplastic astrocytoma fared significantly better than those with glioblastoma multiforme. Both univariate and multivariate Cox analyses confirmed independent influence of these prognosticators. When progression-free survival was used as an endpoint, all seven variables remained independent prognosticators. This study showed that sex, age, KPS, tumor size, tumor location, histology, and extent of surgery are independent prognosticators in patients with malignant glioma treated with combined modality approach.

Hypofractionated intensity-modulated radiotherapy for primary glioblastoma multiforme

PURPOSE

A pilot study was designed to evaluate the safety and efficacy of a novel regimen of hypofractionated intensity-modulated radiotherapy (RT) in the adjuvant treatment of primary glioblastoma multiforme (GBM). The rationale of the study was to combine the potential radiobiologic advantage of hypofractionation to GBM with a highly conformal radiotherapeutic technique. The study was designed to measure the acute and chronic morbidity of patients treated with this regimen, response of GBM to the treatment, overall survival, and time to disease progression after therapy completion.

METHODS AND MATERIALS

Twenty eligible patients were accrued between February 1999 and May 2000 for the study. All patients had Karnofsky performance scores of >/=70. All patients were treated with intensity-modulated RT using the NOMOS Peacock system. A dose of 50 Gy was delivered in 5-Gy daily fractions within 2 weeks to enhancing primary disease, residual tumor, or surgical cavity. Simultaneously, 30 Gy was prescribed in 3-Gy daily fractions to surrounding edema. The time to progression was measured with serial neurologic examinations and MRI or CT scans after RT completion. Acute and late toxicity was graded using Radiation Therapy Oncology Group neurotoxicity scores.

RESULTS

Of the 20 patients, 18 were evaluated for outcome. The median time to disease progression was 6 months after RT completion. The median overall survival was 7 months after treatment completion. All recurrences were within 2 cm of the operative bed. Neurotoxicity during therapy was minimal, with all patients experiencing Grade 0 or 1 toxicity. Late toxicity included 10 patients with Grade 0, 2 patients with Grade 2, and 3 patients with Grade 4 toxicity, manifesting as brain necrosis requiring surgical reexcision. The survival of the 3 patients with brain necrosis was 23, 20, and 9 months. Mortality in all cases was the result of tumor recurrence, with no mortality resulting from brain necrosis.

CONCLUSION

This regimen of hypofractionated intensity-modulated RT did not improve the time to disease progression or overall survival compared with historical experience using conventional fractionation. However, the treatment duration was reduced from 6 weeks to 2 weeks, which may be of palliative benefit in certain subsets of patients. This treatment regimen demonstrated a greater incidence of brain necrosis requiring surgical intervention; however, the 3 patients experiencing this toxicity had longer survival times. Future investigation may be useful to determine which fraction size may be optimal for GBM when highly conformal RT is used in the adjuvant setting.

Hyperfractionated radiation therapy for incompletely resected supratentorial low-grade glioma: a 10-year update of a phase II study

PURPOSE

To provide a 10-year update of hyperfractionated radiation therapy (Hfx RT) in adults with incompletely resected supratentorial low-grade glioma.

METHODS AND MATERIALS

A total of 37 patients were treated with 55 Gy in 50 fractions in 25 treatment days in 5 weeks to tumor plus 2 cm, and additional 17.6 Gy given in 16 fractions in 8 treatment days in 1.5 weeks to tumor plus 1 cm, (1.1 Gy twice daily). Total dose was 72.6 Gy in 66 fractions in 33 treatment days in 6.5 weeks.

RESULTS

After a median follow-up time of 121 months for all patients, the median survival time (MST) for all 37 patients was 145 months, whereas 10-year survival rate was 67%. Median time to tumor progression (MTP) has not yet been attained, but 10-year progression-free survival (PFS) rate was 62%. There was no difference in survival or PFS regarding gender, age, location, site, size, CT enhancement, and histology; whereas lower KPS, higher neurologic status, and lesser extent of surgery had an adverse influence. Infield progression occurred in 15 (88%), whereas in only 2 (12%) patients, tumor progression was described as marginal. Brain necrosis has not been observed so far. Autopsy findings confirmed recurrent glioma and excluded post-RT necrosis in 14 (38%) patients. Of those, 7 (50%) patients had either Grade 3 (n = 4) or Grade 4 (n = 3) glioma.

CONCLUSION

High-dose HFX RT is effective with mild to moderate toxicity. Further studies are warranted with more patients before testing it against standard fractionation RT in this patient population.

Multivariate analysis of clinical prognostic factors in patients with glioblastoma multiforme treated with a combined modality approach

We investigated the influence of various clinical prognostic factors in patients with glioblastoma multiforme (GBM) treated with a combined modality approach. A total of 175 patients with GBM was treated in four consecutive prospective phase II studies using surgery, hyperfractionated or accelerated hyperfractionated radiotherapy (RT) and either adjuvant or concurrent or pre-irradiation chemotherapy (CHT) between January 1988 and December 1993. The median survival time for all 175 patients was 14 months and 1-3-year survival (OS) rates were 57%, 34% and 24%, respectively. The median time to tumour progression was 12 months, and 1-3-year progression-free survival (PFS) rates were 43%, 11% and 7%, respectively. Survival analysis showed that of all investigated prognostic factors, only gender did not influence survival. Patients </=55 years did better than those >55 years; patients with KPS 80-100 did better than those with KPS 50-70; patients with frontal tumours did better than those with tumours in other locations; patients with tumours up to 4 cm did better than those with larger tumours, as did patients with either subtotal or gross total tumour resection when compared to those undergoing biopsy only. Multivariate analysis showed that gender and tumour location did not independently influence survival. When PFS was used as the endpoint, only gender did not influence PFS, as confirmed by multivariate analysis.

Role of radiation therapy and radiosurgery in glioblastoma multiforme

Randomized trials have supported a role for radiation therapy in the initial management of Glioblastoma Multiforme (GBM) for over twenty-five years. Although technological advances in imaging and three-dimensional treatment planning have reduced the toxicity for patients and have allowed safe radiation dose escalation, unfortunately they have not produced a correspondingly dramatic improvement in overall survival. The dose of 60 Gy partial brain RT remains the standard of care for patients with newly diagnosed GBM. Recently completed randomized trials of brachytherapy and radiosurgery do not support these modalities in the initial management of GBM, but these and other focal RT techniques such as intensity modulated radiation therapy enable safe retreatment in selected patients. Future studies will need to explore radiation biologic response modification and radiosensitization through targeted therapies.

Radiotherapy for newly diagnosed malignant glioma in adults: a systematic review

PURPOSE

A systematic review was conducted to develop guidelines for radiotherapy in adult patients with newly diagnosed malignant glioma.

METHODS

MEDLINE, CANCERLIT, the Cochrane Library, and relevant conference proceedings were searched to identify randomized trials and meta-analyses.

RESULTS

Pooling of six randomized trials detected a significant survival benefit favouring post-operative radiotherapy compared with no radiotherapy (risk ratio, 0.81; 95% confidence interval, 0.74 to 0.88, P<0.00001). Two randomized trials demonstrated no significant difference in survival rates for whole brain radiation versus more local fields that encompass the enhancing primary plus a 2 cm margin. A randomized trial detected a small improvement in survival with 60 Gy in 30 fractions over 45 Gy in 20 fractions. Radiation dose intensification and radiation sensitizer approaches have not demonstrated superior survival rates compared with conventionally fractionated doses of 50-60 Gy.

CONCLUSIONS

Post-operative external beam radiotherapy is recommended as standard therapy for patients with malignant glioma. The high-dose volume should incorporate the enhancing tumour plus a limited margin (e.g. 2 cm) for the planning target volume, and the total dose delivered should be in the range of 50-60 Gy in fraction sizes of 1.8-2.0 Gy. Radiation dose intensification and radiation sensitizer approaches are not recommended as standard care. For patients older than age 70, preliminary data suggest that the same survival benefit can be achieved with less morbidity using a shorter course of radiotherapy. Supportive care alone is a reasonable therapeutic option in patients older than age 70 with a poor performance status.