Misonidazole combined with hyperfractionation in the management of malignant glioma

Stereotactic radiosurgery of radioresistant glioblastomas. The ways of overcoming radioresistance of hypoxic tumors

Background. Taking into account high degree of resistance of glioblastoma to radiation therapy, and also low overall survival rates of patients, it is necessary to develop improved methods of treating this pathology, in particular, complex combined treatment with radiation therapy and radiosensitizers. Purpose – to assess the effectiveness of radiosensitization of hypoxic tumors in radiosurgical treatment of glioblastomas; to increase non-recurrent and overall survival rate of patients. Materials and methods. Stereotactic radiosurgery (SRS) of glioblastoma was performed in 106 patients (average age – 53 years), 66 males (62,26%) and 40 females (37,73%). The average dose was 18 Gy in a single-fraction SRS, and 32 Gy (7 Gy per fraction) in multi-fraction SRS. The average volume tumor was 29 cm3 . The treatment group consisted of 66 patients who underwent SRS with radiosensitization. 40 patients made up the control group and underwent SRS without radiosensitization. Results. Median overall survival (MOS) was 20 months in the group with radiosensitization, whereas in the control group it was 12 months. 10-month recurrence-free period after radiosurgery was observed in 95,4% of the patients of the group with radiosensitization and in 70,6% of the patients of the control group. MOS after SRS was similar between the patients with wild-type IDH tumors and patients with tumors with IDH mutation (10,0 months and 11,0 months respectively), and also between the patients with MGMT-methylated tumors and patients with MGMT-nonmethylated tumors (11,2 and 10,2 months respectively). Among all the treated patients, in 20 of them (16,6%) side radiation effects after SRS were observed, and in 9 patients (7,5%) radiation necrosis developed in 3 to 16 months after SRS. The signs of moderate toxicity in the form of vomiting were observed in 6,6% of the patients of the subgroup with metronidazole. There were no signs of toxicity in the subgroup with nimorazole. Conclusions. Radiosensitization improves rates of overall survival by 53,3% and recurrence-free survival by 24,8 % in performing SRS of hypoxic radioresistant glioblastomas. Nimorazole and metronidazole are powerful radiosensitizers which increase radiosensitivity of tumor cells through enhancing oxygen saturation of hypoxic cells. In order to determine indications for performing SRS with radiosensitization and periods for performing an SRS session we must take into consideration the result of an oxygen test (level of oxygen saturation of the tumor), the peak of signal intensity in the zone of active tumor growth and the peak of saturation of the whole tumor volume.

The use of radiosensitizing agents in the therapy of glioblastoma multiforme-a comprehensive review

BACKGROUND

Glioblastoma is the most common malignant brain tumor in human adults. Despite several improvements in resective as well as adjuvant therapy over the last decades, its overall prognosis remains poor. As a means of improving patient outcome, the possibility of enhancing radiation response by using radiosensitizing agents has been tested in an array of studies.

METHODS

A comprehensive review of clinical trials involving radiation therapy in combination with radiosensitizing agents on patients diagnosed with glioblastoma was performed in the National Center for Biotechnology Information's PubMed database.

RESULTS

A total of 96 papers addressing this matter were published between 1976 and 2021, of which 63 matched the subject of this paper. All papers were reviewed, and their findings discussed in the context of their underlining mechanisms of radiosensitization.

CONCLUSION

In the history of glioblastoma treatment, several approaches of optimizing radiation-effectiveness using radiosensitizers have been made. Even though several different strategies and agents have been explored, clear evidence of improved patient outcome is still missing. Tissue-selectiveness and penetration of the blood-brain barrier seem to be major roadblocks; nevertheless, modern strategies try to circumvent these obstacles, using novel sensitizers based on preclinical data or alternative ways of delivery.

Current Landscape and Future Prospects of Radiation Sensitizers for Malignant Brain Tumors: A Systematic Review

BACKGROUND

Radiation therapy (RT) is the cornerstone of management of malignant brain tumors, but its efficacy is limited in hypoxic tumors. Although numerous radiosensitizer compounds have been developed to enhance the effect of RT, progress has been stagnant. Through this systematic review, we provide an overview of radiosensitizers developed for malignant brain tumors, summarize their safety and efficacy, and evaluate areas for possible improvement.

METHODS

Following PRISMA guidelines, PubMed, EMBASE, Cochrane, and Web of Science were searched using terminology pertaining to radiosensitizers for brain tumor RT. Articles reporting clinical evidence of nonantineoplastic radiosensitizers with RT for malignant central nervous system tumors were included. Data of interest were presumed mechanism of action, median overall survival (OS), progression-free survival (PFS), and adverse events.

RESULTS

Twenty-two unique radiosensitizers were identified. Only 2/22 agents (fluosol with oxygen, and efaproxiral) showed improvement in OS in patients with glioblastoma and brain metastasis, respectively. A larger study was not able to confirm the latter. Improved PFS was reported with use of metronidazole, sodium glycididazole, and chloroquine. There was a wide range of toxicities, which prompted change of schedule or complete discontinuation of 9 agents.

CONCLUSIONS

Progress in radiosensitizers for malignant CNS tumors has been limited. Only 2 radiosensitizers have shown limited improvement in survival. Alternative strategies such as synthetic drug design, based on a mechanism of action that is independent of crossing the blood-brain barrier, may be necessary. Use of drug development strategies using new technologies to overcome past challenges is necessary.

2-Nitroimidazoles induce mitochondrial stress and ferroptosis in glioma stem cells residing in a hypoxic niche

Under hypoxic conditions, nitroimidazoles can replace oxygen as electron acceptors, thereby enhancing the effects of radiation on malignant cells. These compounds also accumulate in hypoxic cells, where they can act as cytotoxins or imaging agents. However, whether these effects apply to cancer stem cells has not been sufficiently explored. Here we show that the 2-nitroimidazole doranidazole potentiates radiation-induced DNA damage in hypoxic glioma stem cells (GSCs) and confers a significant survival benefit in mice harboring GSC-derived tumors in radiotherapy settings. Furthermore, doranidazole and misonidazole, but not metronidazole, manifested radiation-independent cytotoxicity for hypoxic GSCs that was mediated by ferroptosis induced partially through blockade of mitochondrial complexes I and II and resultant metabolic alterations in oxidative stress responses. Doranidazole also limited the growth of GSC-derived subcutaneous tumors and that of tumors in orthotopic brain slices. Our results thus reveal the theranostic potential of 2-nitroimidazoles as ferroptosis inducers that enable targeting GSCs in their hypoxic niche.

Koike et al. show that the 2-nitroimidazole doranidazole increases radiation-induced DNA damage in hypoxic glioma stem cells (GSCs). They further demonstrate that additional radiation-independent cytotoxicity of 2-nitroimidazoles is due to ferroptosis that occurs through blockade of mitochondrial complexes I and II leading to metabolic changes in the oxidative stress response.

External beam radiation dose escalation for high grade glioma

BACKGROUND

This is an updated version of the original Cochrane Review published in Issue 8, 2016. High grade glioma (HGG) is a rapidly growing brain tumour in the supporting cells of the nervous system, with several subtypes such as glioblastoma (grade IV astrocytoma), anaplastic (grade III) astrocytoma and anaplastic (grade III) oligodendroglioma. Studies have investigated the best strategy to give radiation to people with HGG. Conventional fractionated radiotherapy involves giving a daily radiation dose (called a fraction) of 180 cGy to 200 cGy. Hypofractionated radiotherapy uses higher daily doses, which reduces the overall number of fractions and treatment time. Hyperfractionated radiotherapy which uses a lower daily dose with a greater number of fractions and multiple fractions per day to deliver a total dose at least equivalent to external beam daily conventionally fractionated radiotherapy in the same time frame. The aim is to reduce the potential for late toxicity. Accelerated radiotherapy (dose escalation) refers to the delivery of multiple fractions per day using daily doses of radiation consistent with external beam daily conventionally fractionated radiotherapy doses. The aim is to reduce the overall treatment time; typically, two or three fractions per day may be delivered with a six to eight hour gap between fractions.

OBJECTIVES

To assess the effects of postoperative external beam radiation dose escalation in adults with HGG.

SEARCH METHODS

We searched CENTRAL, MEDLINE Ovid and Embase Ovid to August 2019 for relevant randomised phase III trials.

SELECTION CRITERIA

We included adults with a pathological diagnosis of HGG randomised to the following external beam radiation regimens: daily conventionally fractionated radiotherapy versus no radiotherapy; hypofractionated radiotherapy versus daily conventionally fractionated radiotherapy; hyperfractionated radiotherapy versus daily conventionally fractionated radiotherapy or accelerated radiotherapy versus daily conventionally fractionated radiotherapy.

DATA COLLECTION AND ANALYSIS

The primary outcomes were overall survival and adverse effects. The secondary outcomes were progression free survival and quality of life. We used the standard methodological procedures expected by Cochrane. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

Since the last version of this review, we identified no new relevant trials for inclusion. We included 11 randomised controlled trials (RCTs) with 2062 participants and 1537 in the relevant arms for this review. There was an overall survival benefit for people with HGG receiving postoperative radiotherapy compared to the participants receiving postoperative supportive care. For the four pooled RCTs (397 participants), the overall hazard ratio (HR) for survival was 2.01 favouring postoperative radiotherapy (95% confidence interval (CI) 1.58 to 2.55; P < 0.00001; moderate-certainty evidence). Although these trials may not have completely reported adverse effects, they did not note any significant toxicity attributable to radiation. Progression free survival and quality of life could not be pooled due to lack of data. Overall survival was similar between hypofractionated and conventional radiotherapy in five trials (943 participants), where the HR was 0.95 (95% CI 0.78 to 1.17; P = 0.63; very low-certainty evidence. The trials reported that hypofractionated and conventional radiotherapy were well tolerated with mild acute adverse effects. These trials only reported one participant in the hypofractionated arm developing symptomatic radiation necrosis that required surgery. Progression free survival and quality of life could not be pooled due to the lack of data. Overall survival was similar between hypofractionated and conventional radiotherapy in the subset of two trials (293 participants) which included participants aged 60 years and older with glioblastoma. For this category, the HR was 1.16 (95% CI 0.92 to 1.46; P = 0.21; high-certainty evidence). There were two trials which compared hyperfractionated radiotherapy versus conventional radiation and one trial which compared accelerated radiotherapy versus conventional radiation. However, the results could not be pooled. The conventionally fractionated radiotherapy regimens were 4500 cGy to 6000 cGy given in 180 cGy to 200 cGy daily fractions, over five to six weeks. All trials generally included participants with World Health Organization (WHO) performance status from 0 to 2 and Karnofsky performance status of 50 and higher. The risk of selection bias was generally low among these RCTs. The number of participants lost to follow-up for the outcome of overall survival was low. Attrition, performance, detection and reporting bias for the outcome of overall survival was low. There was unclear attrition, performance, detection and reporting bias relating to the outcomes of adverse effects, progression free survival and quality of life.

AUTHORS' CONCLUSIONS

Postoperative conventional daily radiotherapy probably improves survival for adults with good performance status and HGG compared to no postoperative radiotherapy. Hypofractionated radiotherapy has similar efficacy for survival compared to conventional radiotherapy, particularly for individuals aged 60 years and older with glioblastoma. There are insufficient data regarding hyperfractionation versus conventionally fractionated radiation (without chemotherapy) and for accelerated radiation versus conventionally fractionated radiation (without chemotherapy). There are HGG subsets who have poor prognosis even with treatment (e.g. glioblastoma histology, older age and poor performance status). These HGG individuals with poor prognosis have generally been excluded from randomised trials based on poor performance status. No randomised trial has compared comfort measures or best supportive care with an active intervention using radiotherapy or chemotherapy in these people with poor prognosis. Since the last version of this review, we found no new relevant studies. The search identified three new trials, but all were excluded as none had a conventionally fractionated radiotherapy arm.

Treatment of newly diagnosed glioblastoma in the elderly: a network meta-analysis

BACKGROUND

A glioblastoma is a fatal type of brain tumour for which the standard of care is maximum surgical resection followed by chemoradiotherapy, when possible. Age is an important consideration in this disease, as older age is associated with shorter survival and a higher risk of treatment-related toxicity.

OBJECTIVES

To determine the most effective and best-tolerated approaches for the treatment of elderly people with newly diagnosed glioblastoma. To summarise current evidence for the incremental resource use, utilities, costs and cost-effectiveness associated with these approaches.

SEARCH METHODS

We searched electronic databases including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and Embase to 3 April 2019, and the NHS Economic Evaluation Database (EED) up to database closure. We handsearched clinical trial registries and selected neuro-oncology society conference proceedings from the past five years.

SELECTION CRITERIA

Randomised trials (RCTs) of treatments for glioblastoma in elderly people. We defined 'elderly' as 70+ years but included studies defining 'elderly' as over 65+ years if so reported.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods for study selection and data extraction. Where sufficient data were available, treatment options were compared in a network meta-analysis (NMA) using Stata software (version 15.1). For outcomes with insufficient data for NMA, pairwise meta-analysis were conducted in RevMan. The GRADE approach was used to grade the evidence.

MAIN RESULTS

We included 12 RCTs involving approximately 1818 participants. Six were conducted exclusively among elderly people (either defined as 65 years or older or 70 years or older) with newly diagnosed glioblastoma, the other six reported data for an elderly subgroup among a broader age range of participants. Most participants were capable of self-care. Study quality was commonly undermined by lack of outcome assessor blinding and attrition. NMA was only possible for overall survival; other analyses were pair-wise meta-analyses or narrative syntheses. Seven trials contributed to the NMA for overall survival, with interventions including supportive care only (one trial arm); hypofractionated radiotherapy (RT40; four trial arms); standard radiotherapy (RT60; five trial arms); temozolomide (TMZ; three trial arms); chemoradiotherapy (CRT; three trial arms); bevacizumab with chemoradiotherapy (BEV_CRT; one trial arm); and bevacizumab with radiotherapy (BEV_RT). Compared with supportive care only, NMA evidence suggested that all treatments apart from BEV_RT prolonged survival to some extent. Overall survival High-certainty evidence shows that CRT prolongs overall survival (OS) compared with RT40 (hazard ratio (HR) 0.67, 95% confidence interval (CI) 0.56 to 0.80) and low-certainty evidence suggests that CRT may prolong overall survival compared with TMZ (TMZ versus CRT: HR 1.42, 95% CI 1.01 to 1.98). Low-certainty evidence also suggests that adding BEV to CRT may make little or no difference (BEV_CRT versus CRT: HR 0.83, 95% CrI 0.48 to 1.44). We could not compare the survival effects of CRT with different radiotherapy fractionation schedules (60 Gy/30 fractions and 40 Gy/15 fractions) due to a lack of data. When treatments were ranked according to their effects on OS, CRT ranked higher than TMZ, RT and supportive care only, with the latter ranked last. BEV plus RT was the only treatment for which there was no clear benefit in OS over supportive care only.   One trial comparing tumour treating fields (TTF) plus adjuvant chemotherapy (TTF_AC) with adjuvant chemotherapy alone could not be included in the NMA as participants were randomised after receiving concomitant chemoradiotherapy, not before. Findings from the trial suggest that the intervention probably improves overall survival in this selected patient population. We were unable to perform NMA for other outcomes due to insufficient data. Pairwise analyses were conducted for the following. Quality of life Moderate-certainty narrative evidence suggests that overall, there may be little difference in QoL between TMZ and RT, except for discomfort from communication deficits, which are probably more common with RT (1 study, 306 participants, P = 0.002). Data on QoL for other comparisons were sparse, partly due to high dropout rates, and the certainty of the evidence tended to be low or very low. Progression-free survival High-certainty evidence shows that CRT increases time to disease progression compared with RT40 (HR 0.50, 95% CI 0.41 to 0.61); moderate-certainty evidence suggests that RT60 probably increases time to disease progression compared with supportive care only (HR 0.28, 95% CI 0.17 to 0.46), and that BEV_RT probably increases time to disease progression compared with RT40 alone (HR 0.46, 95% CI 0.27 to 0.78). Evidence for other treatment comparisons was of low- or very low-certainty. Severe adverse events Moderate-certainty evidence suggests that TMZ probably increases the risk of grade 3+ thromboembolic events compared with RT60 (risk ratio (RR) 2.74, 95% CI 1.26 to 5.94; participants = 373; studies = 1) and also the risk of grade 3+ neutropenia, lymphopenia, and thrombocytopenia. Moderate-certainty evidence also suggests that CRT probably increases the risk of grade 3+ neutropenia, leucopenia and thrombocytopenia compared with hypofractionated RT alone. Adding BEV to CRT probably increases the risk of thromboembolism (RR 16.63, 95% CI 1.00 to 275.42; moderate-certainty evidence). Economic evidence There is a paucity of economic evidence regarding the management of newly diagnosed glioblastoma in the elderly. Only one economic evaluation on two short course radiotherapy regimen (25 Gy versus 40 Gy) was identified and its findings were considered unreliable.

AUTHORS' CONCLUSIONS

For elderly people with glioblastoma who are self-caring, evidence suggests that CRT prolongs survival compared with RT and may prolong overall survival compared with TMZ alone. For those undergoing RT or TMZ therapy, there is probably little difference in QoL overall. Systemic anti-cancer treatments TMZ and BEV carry a higher risk of severe haematological and thromboembolic events and CRT is probably associated with a higher risk of these events. Current evidence provides little justification for using BEV in elderly patients outside a clinical trial setting. Whilst the novel TTF device appears promising, evidence on QoL and tolerability is needed in an elderly population. QoL and economic assessments of CRT versus TMZ and RT are needed. More high-quality economic evaluations are needed, in which a broader scope of costs (both direct and indirect) and outcomes should be included.

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.

External beam radiation dose escalation for high grade glioma

BACKGROUND

The incidence of high grade glioma (HGG) is approximately 5 per 100,000 person-years in Europe and North America.

OBJECTIVES

To assess the effects of postoperative external beam radiation dose escalation in adults with HGG.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2015, Issue 9), MEDLINE (1977 to October 2015) and Embase (1980 to end October 2015) for relevant randomised phase III trials.

SELECTION CRITERIA

We included adults with a pathological diagnosis of HGG randomised to the following external beam radiation regimens.1. Daily conventionally fractionated radiation therapy versus no radiation therapy.2. Hypofractionated radiation therapy versus daily conventionally fractionated radiation therapy.3. Hyperfractionated radiation therapy versus daily conventionally fractionated radiation therapy.4. Accelerated radiation therapy versus daily conventionally fractionated radiation therapy.

DATA COLLECTION AND ANALYSIS

The primary outcomes were overall survival and adverse effects. The secondary outcomes were progression-free survival and quality of life. We used the standard methodological procedures expected by Cochrane. We used the GRADE approach, as outlined by Cochrane, to interpret the overall quality of the evidence from included studies.

MAIN RESULTS

We included 11 randomised controlled trials (RCTs) with a total of 2062 participants and 1537 in the relevant arms for this review. There was an overall survival benefit for HGG participants receiving postoperative radiotherapy compared to the participants receiving postoperative supportive care. For the four pooled RCTs (397 participants), the overall hazard ratio (HR) for survival was 2.01 (95% confidence interval (CI) 1.58 to 2.55, P < 0.00001), moderate GRADE quality evidence favouring postoperative radiotherapy. Although these trials may not have completely reported adverse effects, they did not note any significant toxicity attributable to radiation. Progression free survival and quality of life could not be pooled due to lack of data.Overall survival was similar between hypofractionated versus conventional radiotherapy in five trials (943 participants), where the HR was 0.95 (95% CI 0.78 to 1.17, P = 0.63), very low GRADE quality evidence. The trials reported that hypofractionated and conventional radiotherapy were well tolerated with mild acute adverse effects. These trials only reported one patient in the hypofractionated arm developing symptomatic radiation necrosis that required surgery. Progression free survival and quality of life could not be pooled due to the lack of data.Overall survival was also similar between hypofractionated versus conventional radiotherapy in the subset of two trials (293 participants) which included 60 years and older participants with glioblastoma. For this category, the HR was 1.16 (95% CI 0.92 to 1.46, P = 0.21), high GRADE quality evidence.There were two trials which compared hyperfractionated radiation therapy versus conventional radiation and one trial which compared accelerated radiation therapy versus conventional radiation. However, the results could not be pooled.The conventionally fractionated radiation therapy regimens were 4500 to 6000 cGy given in 180 to 200 cGy daily fractions, over 5 to 6 weeks.All these trials generally included participants with World Health Organization (WHO) performance status from 0 to 2 and Karnofsky performance status of 50 and higher.The risk of selection bias was generally low among these randomized trials. The number of participants lost to follow-up for the outcome of overall survival was low. Attrition, performance, detection and reporting bias for the outcome of overall survival was low. There was unclear attrition, performance, detection and reporting bias relating to the outcomes of adverse effects, progression free survival and quality of life.

AUTHORS' CONCLUSIONS

Postoperative conventional daily radiotherapy improves survival for adults with good performance status and HGG as compared to no postoperative radiotherapy.Hypofractionated radiation therapy has similar efficacy for survival as compared to conventional radiotherapy, particularly for individuals aged 60 and older with glioblastoma.There is insufficient data regarding hyperfractionation versus conventionally fractionated radiation (without chemotherapy) and for accelerated radiation versus conventionally fractionated radiation (without chemotherapy).There are HGG subsets who have poor prognosis even with treatment (e.g. glioblastoma histology, older age and poor performance status). These poor prognosis HGG individuals have generally been excluded from the randomised trials based on poor performance status. No randomised trial has compared comfort measures or best supportive care with an active intervention using radiotherapy or chemotherapy in these poor prognosis patients.

Radioresistance of Brain Tumors

Radiation therapy (RT) is frequently used as part of the standard of care treatment of the majority of brain tumors. The efficacy of RT is limited by radioresistance and by normal tissue radiation tolerance. This is highlighted in pediatric brain tumors where the use of radiation is limited by the excessive toxicity to the developing brain. For these reasons, radiosensitization of tumor cells would be beneficial. In this review, we focus on radioresistance mechanisms intrinsic to tumor cells. We also evaluate existing approaches to induce radiosensitization and explore future avenues of investigation.

Limited margins using modern radiotherapy techniques does not increase marginal failure rate of glioblastoma

OBJECTIVE

We investigate the patterns of failure in the treatment of glioblastoma (GBM) based on clinical target volume (CTV) margin size, dose delivered to the site of initial failure, and the use of temozolomide and intensity-modulated radiotherapy (IMRT).

METHODS

Between August 2000 and May 2010, 161 patients with GBM were treated with radiotherapy with or without concurrent temozolomide. Patients were treated with CTV expansions that ranged from 5 to 20 mm using a shrinking field technique. Patterns of failure and time to progression and overall survival were compared based on CTV margin, use of temozolomide, and use of IMRT. Kaplan Meier analysis was used to estimate survival times, and χ test was used for comparison of cohorts.

RESULTS

For patients treated with 5-, 10-, and 15- to 20-mm CTV, 79%, 77%, and 86% experienced failures in the 60 Gy volume, respectively. Forty-eight percent, 55%, and 66% of patients with 5-, 10-, and 15- to 20-mm CTV experienced failures in the 46 Gy volume, respectively. There was no statistical difference between patients treated with 5-, 10-, 15- to 20-mm margins with regard to 60 Gy failure (P=0.76), 46 Gy failure (P=0.51), or marginal failure (P=0.73). Eighty percent of patients receiving temozolomide experienced failures in the 60 Gy volume. There was no increased likelihood of marginal failures in patients receiving IMRT (P=0.97).

CONCLUSIONS

Modern treatment techniques including use of concurrent temozolmide, limited CTV margin size, and IMRT have not greatly changed the patterns of failure of GBM.

Sustained radiosensitization of hypoxic glioma cells after oxygen pretreatment in an animal model of glioblastoma and in vitro models of tumor hypoxia

Glioblastoma multiforme (GBM) is the most common and lethal form of brain cancer and these tumors are highly resistant to chemo- and radiotherapy. Radioresistance is thought to result from a paucity of molecular oxygen in hypoxic tumor regions, resulting in reduced DNA damage and enhanced cellular defense mechanisms. Efforts to counteract tumor hypoxia during radiotherapy are limited by an attendant increase in the sensitivity of healthy brain tissue to radiation. However, the presence of heightened levels of molecular oxygen during radiotherapy, while conventionally deemed critical for adjuvant oxygen therapy to sensitize hypoxic tumor tissue, might not actually be necessary. We evaluated the concept that pre-treating tumor tissue by transiently elevating tissue oxygenation prior to radiation exposure could increase the efficacy of radiotherapy, even when radiotherapy is administered after the return of tumor tissue oxygen to hypoxic baseline levels. Using nude mice bearing intracranial U87-luciferase xenografts, and in vitro models of tumor hypoxia, the efficacy of oxygen pretreatment for producing radiosensitization was tested. Oxygen-induced radiosensitization of tumor tissue was observed in GBM xenografts, as seen by suppression of tumor growth and increased survival. Additionally, rodent and human glioma cells, and human glioma stem cells, exhibited prolonged enhanced vulnerability to radiation after oxygen pretreatment in vitro, even when radiation was delivered under hypoxic conditions. Over-expression of HIF-1α reduced this radiosensitization, indicating that this effect is mediated, in part, via a change in HIF-1-dependent mechanisms. Importantly, an identical duration of transient hyperoxic exposure does not sensitize normal human astrocytes to radiation in vitro. Taken together, these results indicate that briefly pre-treating tumors with elevated levels of oxygen prior to radiotherapy may represent a means for selectively targeting radiation-resistant hypoxic cancer cells, and could serve as a safe and effective adjuvant to radiation therapy for patients with GBM.

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.

Estimation of radiobiologic parameters and equivalent radiation dose of cytotoxic chemotherapy in malignant glioma

PURPOSE

To determine the radiobiologic parameters for high-grade gliomas.

METHODS AND MATERIALS

The biologic effective dose concept is used to estimate the alpha/beta ratio and K (dose equivalent for tumor repopulation/d) for high-grade glioma patients treated in a randomized fractionation trial. The equivalent radiation dose of temozolomide (Temodar) chemotherapy was estimated from another randomized study. The method assumes that the radiotherapy biologic effective dose is proportional to the adjusted radiotherapy survival duration of high-grade glioma patients.

RESULTS

The median tumor alpha/beta and K estimate is 9.32 Gy and 0.23 Gy/d, respectively. Using the published surviving fraction after 2-Gy exposure (SF2) data, and the above alpha/beta ratio, the estimated median alpha value was 0.077 Gy(-1), beta was 0.009 Gy(-2), and the cellular doubling time was 39.5 days. The median equivalent biologic effective dose of temozolomide was 11.03 Gy(9.3) (equivalent to a radiation dose of 9.1 Gy given in 2-Gy fractions). Random sampling trial simulations based on a cure threshold of 70 Gy in high-grade gliomas have shown the potential increase in tumor cure with dose escalation. Partial elimination of hypoxic cells (by chemical hypoxic cell sensitizers or carbon ion therapy) has suggested that considerable gains in tumor control, which are further supplemented by temozolomide, are achievable.

CONCLUSION

The radiobiologic parameters for human high-grade gliomas can be estimated from clinical trials and could be used to inform future clinical trials, particularly combined modality treatments with newer forms of radiotherapy. Other incurable cancers should be studied using similar radiobiologic analysis.

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.

Modified optimal fractionation for poor prognosis malignant gliomas: an elusive search

The prognosis of malignant gliomas has not changed much over the last few decades despite refinements in neurosurgical techniques, high-precision radiotherapy, and newer chemotherapeutic agents. The median survival of poor prognosis malignant gliomas (older and/or poor performance status patients) still remains in the range of 6-9 months following maximal safe resection and postoperative conventionally fractionated adjuvant radiotherapy with or without chemotherapy. However, six weeks of daily radiotherapy does seem inappropriate in relation to the short expected survival time in this subset and there is an increasing emphasis on reducing the overall treatment time and the number of hospital visits by such patients. This can be achieved either by accelerated radiotherapy or by hypofractionated radiation, both of which are equivalent to conventional fractionation in terms of palliative effect and survival, as in discussed in this review. Despite enough evidence, such alteration of fractionation has not gained widespread acceptance by the oncologic fraternity. This review has been conducted to collate the evidence that could help shift the paradigm from conventional to modified fractionation in poor prognosis malignant glioma patients.

External beam and conformal radiotherapy in the management of gliomas

External beam radiotherapy remains an important local treatment modality in both high and low grade gliomas, however its contribution to outcome remains modest. In high grade tumours this is because of their extreme clinical radioresistance, with local recurrences occurring even after doses over 70 Gy. In low grade tumours radiation does not seem to alter the overall pattern of disease progression significantly. Therefore despite use of the new technologies now available that allow radiotherapy to be delivered more accurately and to higher doses, local control of these tumours is still rarely achieved. Unfortunately these tumours have not proven sensitive to changes in radiotherapy fractionation or to the addition of radiosensitising agents. Novel approaches to these tumours are needed, based on an improved understanding of both tumour and normal tissue response to radiation.

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.

Validation of the Medical Research Council and a newly developed prognostic index in patients with malignant glioma: how useful are prognostic indices in routine clinical practice?

Although different prognostic indices for malignant gliomas have been developed, their validity outside of clinical trials has not been widely tested. The aim of this study was to determine whether the Medical Research Council (MRC) brain tumour prognostic index was able to stratify patients for survival managed in routine practice, and secondly to compare the results with our newly developed prognostic score which included tumour grade and only 3 prognostic groups. The MRC and the new prognostic index were calculated for a group of 119 adult patients with malignant glioma managed by surgical resection/biopsy and post-operative radiotherapy. For the MRC and new score, 6 and 3 prognostic groups were defined, respectively. For all patients median survival was 11 (2-66) months. The overall survival rate at 12 and 24 months were 43% and 18%, respectively. The MRC median and two-year survival rates were 14 months and 26% for a score of 1-10, 14 months and 27% for a score of 11-15, 13 months and 22% for a score of 16-20, 8 months and 10% for a score of 21-25, 8 months and 0% for those scoring 26-33. There was only one patient in the 34-38 group. For the new prognostic index, median and two-year survival rates were respectively 16 and 26%; 12 and 23%; 8 and 7% for the good, intermediate and poor prognostic groups. Both indices were significant factors for survival in univariate analysis (MRC index, p = 0.0089, new index p = 0.0002), but not in multivariate analysis. Both the MRC and our newly devised prognostic score were able to separate patients into good and poor prognostic groups, which may aid in treatment decisions, although there was less differentiation between the MRC groups especially over the first year. Both scores use routinely available factors. However, inclusion of tumour grade in the new score may be an advantage over the MRC index.

Safety of thrice-daily hyperfractionated radiation and BCNU for high-grade gliomas

PURPOSE

To investigate the safety of thrice-daily hyperfractionated radiotherapy (RT) given in conjunction with BCNU (carmustine) in high-grade gliomas.

METHODS AND MATERIALS

Patients >18 years old with newly diagnosed high-grade gliomas were eligible. The dose of radiation was 5040 cGy, with a 1440-cGy boost in 180 cGy fractions delivered thrice daily in two 6-day periods with a 2-week interval. BCNU (200 mg/m(2)) was administered on the first day of radiation, then every 7 weeks for 1 year and every 10 weeks for another year.

RESULTS

Eighteen patients were enrolled. The mean age was 49.6 years. Sixteen patients had astrocytomas (Grade 3 or 4 in 5 and 11 patients, respectively) and 2 had oligoastrocytomas (Grade 3 and 4 in 1 patient each). One underwent total resection, 9 subtotal resection, and 8 biopsy only. Thirteen patients had stable disease, 4 regression, and 1 progression. The median time to progression was 37.8 weeks. The median overall survival was 44.4 weeks. Nine patients had neurologic toxicities, including 2 deaths at 69 and 139 weeks.

CONCLUSION

This regimen is unacceptably toxic. Factors that could have contributed to the toxicity may include the total radiation dose, thrice-daily hyperfractionation, and the concurrent use of i.v. BCNU.

Multidisciplinary management of adult anaplastic astrocytomas

The management of patients with anaplastic astrocytoma (AA) requires multidisciplinary involvement. In this article, the literature on the treatment of patients with AA is reviewed, emphasizing randomized trials and key retrospective studies. The role of surgery, radiation therapy, and chemotherapy in newly diagnosed patients and those with recurrent disease is described. Basic science insights, advances in neuroimaging and neuropathology, and novel therapies targeting invasion, angiogenesis, and growth modulation will hopefully lead to improved outcome in this subset of patients with malignant glioma.

[Radiotherapy of glioblastoma]

Glioblastoma cells appear to be inherently radioresistant and to present a significant fraction of hypoxic cells. The most significant prognostic factors to compare results achieved in several series of patients are the age, performance status and quality of surgical resection. Several randomized trials have provided evidence supporting the efficacy of radiation therapy in the treatment of glioblastoma. Prescription of a 60-Gy dose delivered according to a conventional dose-fractionation scheme (single daily fractions of 1.7 to 2 Gy five times per week) in a target volume with a 2-3 cm margin of tissue surrounding the perimeter of the contrast enhancing lesion on computerized tomography and magnetic resonance imaging is derived from observations made in several retrospective and prospective studies. Evidence of improvement in survival was observed neither in patients receiving hyperfractioned and accelerated radiotherapy, nor in patients for whom radiation sensitizers such as nitroimidazole compounds or halogenated pyrimidine analogs were associated to radiation therapy. The addition of nitrosourea to radiotherapy increases the 2-year survival rate by about 10%. Combination of full-dose external beam radiotherapy and brachytherapy or radiosurgery boost in selected patients with glioblastoma leads to an increase in the median survival, while external beam radiation alone in patients with similar prognosis does not.

Acute effects on neuropsychological function and quality of life by high-dose multiple daily fractionated radiotherapy for malignant astrocytomas: assessing the tolerability of a new radiotherapy regimen

Cognitive and other quality of life measures were assessed in 29 patients with supratentorial malignant astrocytomas before and after high-dose (8000 cGy) multiple daily fractionated radiotherapy. Assessments were done immediately before and after radiotherapy. Patients completed a neuropsychological evaluation and the Functional Living Index: Cancer (FLIC). Spouses completed the Family Environment Scale and the Profile of Mood States. Cognitive abilities generally improved over the course of radiotherapy. Occasionally, deterioration of potential clinical importance was observed on functions associated with the tumour site. Quality of life as assessed by the FLIC was stable in most cases and improved in five, but deteriorated in three patients. Families showed slightly less Conflict and slightly more Cohesion than the norm; this was especially so when patients had greater cognitive deficit. Emotional state of spouses was variable, with increased fatigue or reduced activity most commonly reported, followed by depression and anxiety. Mostly this improved with time or remained stable, but two spouses reported worsening emotional state. Results are generally encouraging for tolerance of this radiotherapy protocol, although they demonstrate that limited adverse effects may occur in some cases.

Hyperfractionated and accelerated radiation therapy in central nervous system tumors (malignant gliomas, pediatric tumors, and brain metastases)

The authors review the main contributions of the international literature concerning the role of hyperfractionation (HF), accelerated fractionation (AF), and accelerated hyperfractionation (AHF) of the dose in radiation therapy (RT) of central nervous system tumors. Basic rationales, clinical results, acute/late toxicity, and current prospectives are summarized in three sections focusing on malignant gliomas, pediatric brainstem tumors, and brain metastases. In supratentorial malignant gliomas the superiority of AHF (0.89 Gy x 3 fractions/day; total dose 61.4 Gy) over conventional fractionation ((CF) total dose 58 Gy) was demonstrated by a randomized trial. However, the gain in median survival time was less than 6 months. No other randomized trials support the preferential choice of non-CF schedules outside clinical trials. Ongoing trials are exploring the role of AHF in combination with chemotherapy, hypoxic cell and radiosensitizing agents. As for pediatric brainstem tumors, there are no data to support the routine use of HF that should be preferably used in an investigative setting. As late sequelae have been reported in the few long-term survivors, patients should be carefully selected. Regarding brain metastases AF RT and AHF RT, with their faster treatment course, may represent a convenient alternative to CF RT for the palliation of brain metastases. In carefully selected patients with solitary brain metastases non-CF RT may be part of aggressive treatment approaches.

Current perspectives in gliomas

The annual incidence of primary central nervous system tumors, including gliomas, is increasing, however, the prognosis of these tumors remains poor with a median survival of only 5 years. The imaging of tumors by computerised tomography, magnetic resonance imaging and newer methods such as positron emission tomography and proton magnetic resonance spectroscopy (1H-MRS) is increasing our knowledge of tumor biology and extent of the disease. Advances within the field of neurosurgery have improved operative procedures reducing mortality and morbidity. Furthermore, radiotherapy planning, tumor targeting and repositioning for treatment have all improved initial tumor management. The role of adjuvant chemotherapy remains controversial. Chemotherapy for advanced and recurrent disease has been extensively investigated, and although improvements in quality of life have been recorded, no prolongation of survival has been documented. With new discoveries and increasing knowledge of the physiology and molecular biology of these tumors the potential for targeting therapy at a genetic level is becoming increasingly promising. This review provides an overview of these current perspectives in glioma management.

Hyperfractionation: where do we stand?

Hyperfractionation is generally expected to allow an escalation of total dose, thereby increasing tumour control rate, without increasing the risk of late complications. The purpose of this review is to assess the empirical evidence for this therapeutic gain from hyperfractionated radiotherapy. Although extensive clinical data have been accumulated until now, especially on treatment of head and neck cancer, the line of evidence is not consistent. The present analysis indicates that the dose per fraction generally used in standard radiotherapy is already a good choice.

Hyperfractionated radiotherapy of human tumors: overview of the randomized clinical trials

PURPOSE

Hyperfractionation (HF) is the altered fractionation schedule most frequently studied in clinical Phase III trials. In this overview, surviving fractions, rates of complete responses, and estimates of the long-term locoregional tumor control probabilities after HF and conventional fractionated irradiation (CF) available from the various reports were compared.

METHODS AND MATERIALS

A metaanalysis was performed of the randomized studies on hyperfractionation vs. conventional fractionation published since 1980 on different tumor types in various locations.

RESULTS

Compared with CF, HF significantly reduced the odds of death for patients with head and neck tumors (three studies, odds ratio 0.48 (0.40-0.58), p < 0.0001) and bladder cancer (two studies, odds ratio 0.53 (0.36-0.78), p = 0.001), while there was a trend in nonsmall cell lung cancer (three studies, odds ratio 0.69 (0.51-0.95), p = 0.02), and malignant gliomas (three studies, odds ratio 0.67 (0.48-0.93), p = 0.02). The probability of long-term loco-regional control of head and neck tumors was significantly enhanced after HF (four studies, odds ratio for loco-regional recurrence or related events 0.35 (0.28-0.45), p < 0.0001). In trials on head and neck tumors and bladder cancer, complete responses were seen more often after HF compared with CF (odds ratio for failure of complete response: 0.43 (0.32-0.57), p < 0.0001, and 0.43 (0.27-0.70), p = 0.0007).

CONCLUSIONS

This overview demonstrates that the effectiveness of radiotherapy is consistently higher for HF than for CF. The assumption that tumors have a small effective fractionation sensitivity (alpha/beta > 5 Gy) seems to be fulfilled especially for head and neck cancers.

Final report of a phase I/II trial of hyperfractionated and accelerated hyperfractionated radiation therapy with carmustine for adults with supratentorial malignant gliomas. Radiation Therapy Oncology Group Study 83-02

BACKGROUND

Efforts to improve local control and survival by increasing the dose of once-daily radiation therapy beyond 70 Gray (Gy) for patients with malignant gliomas has yet been unsuccessful. Hyperfractionated radiation therapy (HF) should allow for delivery of a higher total dose without increasing normal tissue late effects, whereas accelerated hyperfractionated radiation therapy (AHF) may minimize tumor repopulation by shortening overall treatment time. The Radiation Therapy Oncology Group (RTOG) conducted a randomized Phase I/II study of escalating doses of HF and AHF either carmustine (bis-chlorethyl nitrosourea [BCNU]) fro adults with supratentorial glioblastoma multiforme (GBM) or anaplastic astrocytoma (AA). Primary study endpoints were overall survival and acute and chronic treatment-related toxicity.

METHODS

From 1983 to 1989, 786 patients with supratentorial gliomas (81% with GBM and 19% with AA) were stratified by histology, age, and performance status and randomized to receive partial brain irradiation, utilizing either HF (1.2 Gy twice daily to doses of 64.8, 72, 76.8, or 81.6 Gy) of AHF (1.6 Gy twice daily to doses of 48 or 54.4 Gy). All patients received carmustine. The distinction of pronistic factors was similar on all arms.

RESULTS

There were 747 eligible and analyzable patients among 786 enrolled patients (95%). Two patients had a Grade 5 and 65 patients had a Grade 4 chemotherapy toxicity. Two patients in the 81.6 Gy arm experienced late Grade 4 radiation toxicity and there was 1 late radiation-associated death in the 54.4 Gy arm. The rate of Grade 3 of worse radiation toxicity at 5 years, calculated by the delivered does level, was 3% in the lowest total dose arms (48 and 54.4 Gy), 4% in the intermediate dose arms (64.8 and 72 Gy), and 5% in the highest dose arms (76.8 and 81.6 Gy) (p = 0.54). Survival rates at 2 and 5 years were: 21% and 11%, and 4%, respectively, for GBM patients. There were no significant differences between the treatment arms with regard to median survival time (MST), when analyzed by the originally assigned dose. The MST for all patients varied between 10.8 months and 12.7 months (P = 0.59); between 9.6 months and 11 months for patients with GBM (P = 0.43); and between 30.4 months and 85.8 months for patients with AA (P = 0.78). Analysis of the survival rates for all patients by dose received rather than by dose assigned revealed a 14% 5-year survival rate for the lower HF doses (64.8 and 73 Gy), 11% for the higher doses (76.8 and 81.6 Gy), and 10% for the AHF doses (48 and 54.4 Gy) (P = 0.1). The subgroup a AA patients had a better MST (49.9 months) in the lower received HF doses than in the higher HF doses (34.6 months) (P = 0.35). In contrast, GM patients who received the higher HF doses had survival superior to the patients in the AHF arms (MST of 11.6 months and 10.2 months, respectively, P = 0.04).

CONCLUSIONS

The use of HF with BCNU and dose escalation up to 81.6 Gy is both feasible and tolerable, although late toxicity increases slightly with increasing dose. The best MST with the least toxicity were observed for AA in the lower received HF doses (72 and 64.8 Gy). Accordingly, 72 Gy in two 1.2 Gy fractions was used as the investigational arm of a completed Phase III trial (RTOG 90-06). In contrast, for GBM patients, longer survival times were noted in the higher received HF doses (78.6 and 81.6 Gy), suggesting the role for further dose escalation. The low toxicity rate with AHF arms suggest that further dose escalation is possible and is currently occurring in RTOG 94-11.

Fast neutrons in the treatment of grade IV astrocytomas

In 1981, the Hôpital Tenon group and the Orléans neutron therapy team initiated a collaborative study for the treatment of grade IV astrocytomas using a combination of photons and neutrons. Neutrons were used as boost in a reduced volume. Doses were progressively increased from 6 to 7 Gy and later up to 8 Gy. Since October 1994, a neutron boost of 7.5 Gy has been delivered. At the time of evaluation, 294 patients had a minimum follow-up of 12 months. Univariate analysis indicated that clinical status, tumor location and photon fractionation scheme had no significant influence on survival. In contrast, age, surgical procedure and neutron dose were found to be prognostic factors. In a multivariate analysis, the prognostic value of the surgical procedure disappeared and the only remaining independent prognostic factors up to 11 months after treatment (P = 0.001) were age and the neutron dose. As far as neutron dose was concerned, survival increased with dose from 6 to 7 Gy up to 15 months. However, after 15 months, there was no longer any benefit in survival for the patients treated with 8 Gy, and complications related to overdosage began to appear. There was a long-term survival group: 55 patients were alive 18 months after treatment (18%). The median survival was 26.7 months. The best survival was observed for patients treated with a neutron boost of 7 Gy in eight fractions over 11 days (25 vs 18%). The present study demonstrates the feasibility of a combination of photons (30 Gy total brain) followed by a neutron boost (7 Gy) in the treatment of high-grade astrocytomas. The results are in good agreement with the published data. In the literature, age and surgical procedure are currently considered as the most important prognostic factors. The prevalence of neutron dose over these two other prognostic factors, as shown in this study, is an important additional argument in favor of the use of neutrontherapy in the management of these tumors. A possible benefit when combining external fast neutrontherapy with boron neutron capture therapy (BNCT) could reasonably be expected.

Stereotactic radiosurgery as an adjunct to surgery and external beam radiotherapy in the treatment of patients with malignant gliomas

PURPOSE

To evaluate the efficacy and toxicity of a stereotactic radiosurgery boost as part of the primary management of a minimally selected population of patients with malignant gliomas.

METHODS AND MATERIALS

Between June, 1991 and January, 1994 a stereotactic radiosurgery boost was given to 30 patients after completion of fractionated external beam radiotherapy. The study population consisted of 22 males and 8 females, with a range in age at treatment from 5 to 74 years (median: 54 years). Tumor volume ranged from 2.1 to 115.5 cubic centimeters (cc) (median: 24 cc). Histology included 17 with glioblastoma multiforme, 10 with anaplastic astrocytoma, 1 with a mixed anaplastic astrocytoma-oligodendroglioma, and 2 with a gliosarcoma. A complete resection was performed in 9 (30%) patients, while 18 (60%) underwent a subtotal resection, and 3 (10%) received a biopsy only. Fractionated radiation dose ranged from 44 to 62 Gy, with a median of 59.4 Gy. Prescribed stereotactic radiosurgery dose ranged from 0.5 to 18 Gy (median: 10 Gy), and the volume receiving the prescription dose ranged from 2.1 to 158.7 cc (median: 46 cc). The volume of tumor receiving the prescription dose ranged from 70-100% (median: 100%). One to four (median: 2) isocenters were used, and collimator size ranged from 12.5 to 50 mm (median size: 32.5 mm). The median minimum stereotactic radiosurgery dose was 70% of the prescription dose and the median maximum dose was 200% of the prescription dose.

RESULTS

With a minimum follow-up of 1 year from radiosurgery, 7 (23%) of the patients are still living and 22 (73%) have died of progressive disease. One patient died of a myocardial infarction 5 months after stereotactic radiosurgery. Follow-up for living patients ranged from 12 to 45 months, with a median of 30 months. The 1- and 2-year disease-specific survival from the date of diagnosis is 57 [95% confidence interval (CI) 39 to 74%] and 25% (95% CI 9 to 41%), respectively (median survival: 13.9 months). No significant acute or late toxicity has been observed.

CONCLUSION

Stereotactic radiosurgery provides a safe and feasible technique for dose escalation in the primary management of unselected malignant gliomas. Longer follow-up and a randomized prospective trial is required to more thoroughly evaluate the role of radiosurgery in the primary management of malignant gliomas.

Hyperfractionated and hypofractionated radiation therapy for human malignant glioma xenograft in nude mice

Xenografts of a human malignant glioma subcutaneously transplanted into nude mice were irradiated with graded single doses (2, 5, 10 or 20 Gy) or five types of fractionation schedules in two weeks: conventional [20 Gy in 10 fractions (fr)], hyperfractionated [24 Gy in 20 fr (two fractions per day)], and hypofractionated-1, 2, 3 [20 Gy, 18 Gy, 16 Gy in 4 fr]. All of the fractionated irradiation groups showed tumor regression. The hypofractionation-1 group (20 Gy in 4 fr) demonstrated the most prominent tumor regression, while the hyperfractionation group (24 Gy in 20 fr) showed the least effect. The hypofractionation-2 group (18 Gy in 4 fr) showed similar regression to the conventional fractionation group (20 Gy in 10 fr). Histologically, tumors in the control groups consisted of a homogenous population of small anaplastic cells, and only a small number of tumor cells were glial fibrillary acidic protein (GFAP)-positive. Following irradiation, the population of small anaplastic cells decreased and the percentage of GFAP-positive cells increased. Cellular pleomorphism became much more prominent after irradiation in all of the fractionated irradiation groups as compared with the graded single dose irradiation groups. In this study, hyperfractionation was not effective against human glioma xenografts compared with conventional fractionation and hypofractionation. This indicates that care is needed in applying hyperfractionation regimens to human malignant gliomas.

Improving the acceptability of high-dose radiotherapy by reducing the duration of treatment: accelerated radiotherapy in high-grade glioma

Radiotherapy, although clearly beneficial in patients with high-grade glioma, is largely palliative, and a protracted course of treatment may not be the most appropriate approach in the context of limited survival. We therefore assessed the feasibility, toxicity and survival results of a short accelerated radiotherapy regimen given twice daily over a period of 3 weeks. A total of 116 patients with high-grade glioma were treated with radiotherapy in a prospective study using an accelerated fractionation regimen. The total dose of 55 Gy was given in 32-36 fractions of 1.72-1.53 Gy, twice daily 5 days a week, with a minimum 6 h interval between fractions. Toxicity was assessed using Karnofsky performance status scale and in the later part of the study with the Barthel index. Survival data were compared with a control group treated with 60 Gy in 30 daily fractions in a previous MRC study, matched for known prognostic factors. The median survival of 116 patients treated with accelerated radiotherapy was 10 months. Survival comparison of accelerated patients with matched controls treated with conventional fractionation demonstrated a hazard ratio of 1.13 (95% confidence interval 0.85-1.51; P = 0.39). Early treatment toxicity was acceptable, with only seven patients developing transient decrease in performance status. The accelerated radiotherapy regimen was logistically feasible and acceptable to patients, carers and staff. Treatment time was reduced without apparent increase in early toxicity and there was no loss of survival benefit. The effectiveness and convenience of a short accelerated regimen makes this a suitable alternative to a 6 week course of radiotherapy in patients with high-grade glioma. However, a full randomised trial comparing conventional and accelerated radiotherapy may be required as proof of equivalence.

Hyperfractionated radiation therapy (HFX RT) followed by multiagent chemotherapy (CHT) in patients with malignant glioma: a phase II study

PURPOSE

Forty-eight patients with malignant glioma were treated with hyperfractionated radiation therapy followed by multiagent chemotherapy to explore feasibility and toxicity of such combined modality treatment.

METHODS AND MATERIALS

There were 34 males and 14 females with a median age of 53 years (range, 32-74 years) and median Eastern Cooperative Oncology Group performance status score of 1 (range, 0-3). Histology included anaplastic astrocytoma in 11 patients and glioblastoma multiforme in 37 patients. Radiation was given at 1.2 Gy per fraction, two fractions per day, for a total dose of 72 Gy, with a reduction in field size after 52.8 Gy. Four weeks after completion of hyperfractionated radiation therapy multiagent chemotherapy was introduced with bischlorethyl nitrosourea (BCNU) 50 mg/m2, days 1-3, vincristine 1.4 mg/m2 (max. 2 mg), day 1, procarbazine 50 mg/m2, days 1-7 and cisplatin 20 mg/m2, days 1-3. Cycles were repeated every 4 weeks to a maximum of six cycles or until tumor progression was noted.

RESULTS

Median survival time for all patients was 52 weeks (range, 16-185 weeks) and median time to tumor progression was 30.5 weeks (range, 12-131 weeks). Besides age, histology, performance status, and extent of surgery, interfraction interval and location of tumor influenced survival in glioblastoma multiforms patients on univariate analysis: Patients treated with shorter intervals (4.5-5 h) did better than those treated with longer intervals (5.5-6 h); also, glioblastoma multiforme patients with frontal tumors did better than those with tumors of the other locations. Multivariate analysis confirmed that the performance status, interfraction interval, and tumor location were significant prognostic factors in glioblastoma multiforme patients. Acute toxicity was mild. No cases of brain necroses were observed.

CONCLUSION

Hyperfractionated radiation therapy followed by multiagent chemotherapy was well tolerated with mild acute and virtually no late toxicity. More patients and longer follow-up are needed for further evaluation of its activity and late effects in anaplastic astrocytoma patients.

Accelerated radiotherapy in glioblastoma multiforme: a dose searching prospective study

The EORTC Radiotherapy Cooperative Group performed a prospective phase II study in glioblastoma multiforme using accelerated radiotherapy in escalating doses. The aims of the study were to investigate acute and late toxicity as well as tumor response and survival. Only the CT-enhanced tumor zone plus a margin of 2-3 cm were treated (mean volume, 1034 +/- 477 cm3). Radiotherapy was administered with 5-18 MV photons. The radiation schedule consisted of 3 fractions of 2 Gy/day, separated with at least 4 h. The first group of patients was scheduled to receive a total dose of 42 Gy, 21 fractions in 9 days. The total dose was then escalated up to 48 Gy (24 fractions in 10 days), 54 Gy (27 fractions in 11 days) and 60 Gy (30 fractions in 12 days). The numbers of patients entered in each dose-level group were 15, 17, 18 and 16, respectively. Acute toxicity was mild, nausea/vomiting was absent in 91% of the patients. In 80% of the patients the neurological condition improved or remained stable compared with the start of radiotherapy but in 58% of the patients steroids were necessary, either increased in dose or initiated. Acute toxicity did not increase with increasing radiation doses although patients treated with 60 Gy more often required steroids than the other groups. Late toxicity was strongly suspected in 2 patients receiving 52 Gy and 56 Gy, respectively. Within the whole group of 66 patients only one recurrence outside the primary site was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiation therapy for malignant astrocytomas in adults

High grade (or malignant) astrocytomas remain a formidable therapeutic challenge. The main prognostic factors are patient age, patient performance status, tumor grade, the extent of surgical resection and the presence of fits. These factors could help to identify different groups of patients and should be an advantage in deciding on treatment strategies. Modern imaging techniques provide a more precise idea of tumor volume. The study of tumor recurrence shows that they occur in the immediate vicinity of the primary site. Surgery aside, radiotherapy remains the most important treatment modality. Currently, its standards concerning optimal dose and target volume appear to be accepted overall. There is no doubt that a dose-response relation exists; however, doses exceeding 60 Gy increase morbidity. Therefore 60 Gy is the dose most often cited in the literature. Furthermore, as whole brain irradiation does not decrease the risk of recurrence, a focal irradiation including a defined mean volume is generally used today. Radiosensitizers and heavy particles have not fulfilled their initial promise. Brachytherapy remains an interesting alternative for a limited number of patients. Nevertheless, it seems to increase recurrence at a distance from the primary site and to lead to severe focal lesions. Interstitial thermoradiotherapy may minimize local doses and thus help avoid serious local necrosis. Amongst the other therapeutic alternatives, intravenous chemotherapy using nitrosoureas provides a certain but modest benefit. Other administration modalities are currently undergoing evaluation. These include intra-arterial chemotherapy or high dose chemotherapy with auto-bone marrow transplantation. The interest of this latter is concerned mainly with anaplastic astrocytomas. Finally, among the future alternatives, gene therapy appears to hold the most promise. Intensive therapies, combined modality treatments, with the recent help of biological innovations, should be proposed to favorable groups of patients.

Pilot study of 6 weeks of chemoradiotherapy with 5 FU and hydroxyurea in malignant gliomas

In an attempt to improve the primary treatment of malignant gliomas we used a concomitant 6-week course of chemoradiotherapy with 5 fluorouracil (5 FU) and hydroxyurea (HU) in 24 adults with anaplastic astrocytoma (AA) (7 cases) or glioblastomas (GLB) (17 cases). This patient population was characterised by a poor prognostic profile; 50% of cases had biopsic or subtotal surgery and 70% had GLB. Patients received 2 Gy/day 18 MV photons with 300 mg/m2 of 5 FU in continuous infusion and 500 mg x 4/day per os of HU, five days per week during 6 weeks. Treatment was poorly tolerated in terms of toxicity and implied heavy logistics (hospitalization, central venous access) worsening the quality of life which is already bad in malignant gliomas. Unfortunately we did not improve median survival which does not exceed 26 weeks with 7 long survivors (> 49 weeks). This pilot study does not offer any benefits over current standard approaches. Aggressive locoregional approaches such as this should perhaps be attempted in patients with a better profile.

A randomized trial of accelerated hyperfractionated radiation therapy and bis-chloroethyl nitrosourea for malignant glioma. A preliminary report of Radiation Therapy Oncology Group 83-02

BACKGROUND

The third and final randomization of Radiation Therapy Oncology Group (RTOG) 83-02 was performed to identify the maximal tolerated dose and potential efficacy of accelerated hyperfractionated radiation therapy (AHRT) in 1.6 Gy twice-daily fractions for adult malignant glioma.

METHODS

From December 1987 to July 1989, 304 patients with malignant glioma were stratified by age, performance status, and histologic findings and randomized to receive total AHRT doses of 48.0 or 54.4 Gy, with 80 mg/m2 of bis-chloroethyl nitrosourea (BCNU) for 3 days every 8 weeks. Distribution of other prognostic factors, including neurologic function, extent of surgery, tumor size, and sex, was comparable in each treatment arm.

RESULTS

One Grade 5 radiation therapy (RT)-related toxic effect was reported (in the 54.4-Gy treatment arm), and the incidence of late Grade 3-5 RT-related toxic effects at 18 months was 1% at 48.0 Gy and 4% at 54.4 Gy. The median survival times (MST) for the 48.0 Gy and 54.4 Gy treatment arms were 11.7 and 10.8 months, respectively, comparable to the MST in prior RTOG trials with a similar proportion of patients with glioblastoma multiforme (79%). For the 123 patients who were 60 years of age or older, the MST for the 48.0 Gy and 54.4 Gy treatment arms were 8.9 and 10.4 months, respectively, and compare favorably with the MST of 6.0 months reported with standard RT and BCNU treatment used for 101 patients who were 60 years of age or older in two prior RTOG malignant glioma trials (74-01 and 79-18). Although these results differ significantly (P = 0.0015), this contrast is not significant when adjusted by performance status.

CONCLUSIONS

The maximum tolerated dose of AHRT has yet to be identified, and pursuit of this information may most benefit patients with malignant glioma who are 60 years of age or older.

Does extent of surgery influence outcome for astrocytoma with atypical or anaplastic foci (AAF)? A report from three Radiation Therapy Oncology Group (RTOG) trials

103 patients with the diagnosis of AAF were identified from the RT/BCNU arms of 3 RTOG malignant glioma trials. Pre-treatment tumor size was less than 5 cm for 48% and greater than or equal to 5 cm for 52%, and tumor sites were frontal lobe in 55%, temporal in 25%, and parietal in 16%. Surgery consisted of biopsy for 30%, partial resection for 56%, and total resection for 14%. Extent of surgery correlated with age, with 81% of patients less than 40 undergoing partial/total resection vs. 60% of those over 40 (P = 0.019). The median survival time (MST) of patients undergoing partial/total resection was 49 mo., vs. 18 mo. for those biopsied only (P = 0.002). Patients with frontal location had longer MST than those with non-frontal lesions (MST: 49 vs. 25 mo., P = 0.047), while no survival difference was apparent by univariate analysis of tumor size. Multivariate analysis demonstrated that only younger age, frontal location, and smaller tumor size correlated significantly with extended survival. Extent of surgery was not predictive. The close correlation between young age and extensive surgery obscures the survival advantage for greater surgery seen with univariate analysis. Smaller tumor size and frontal location favorably influence outcome even when adjusted by age.

Heterogeneity in response to treatment with buthionine sulfoximine or interferon in human malignant glioma cells

Two tumor cell lines were established from each of three human malignant glioma biopsy specimens (M059, M067, M071) and sensitivity to treatment with radiation or chemotherapeutic agents (BCNU, nitrogen mustard) was determined. The effects of recombinant human interferon-alpha (rIFN) on the radiation response and of buthionine sulfoximine (BSO) on the drug response were investigated as well. For tumor M059, two cell lines that differed significantly in radiosensitivity were isolated (surviving fractions at 2 Gy = 0.02 and 0.64). The chemosensitivity and response to chemical modification differed as well. Cell lines established from tumor M071 differed in their response to rIFN only and were not sensitized by BSO. M067 cell lines showed little difference and were not sensitized by either agent. These results suggest that differences may exist both within and among human malignant gliomas with regard to their sensitivity to drugs, radiation, and the ability of chemical agents to modify treatment responses.

Radiosensitivity testing of human primary brain tumor specimens

The inherent radiosensitivity of early passage cells derived from 22 patients with tumors of glial origin has been determined using a clonogenic assay system. The mean (+/- SD) surviving fraction at 2 Gy was 0.37 +/- 0.22 (range = 0.02-0.87). No correlation between inherent radiosensitivity and tumor cell plating efficiency or intracellular glutathione was observed. Tumor cells that were both resistant to nitrosoureas and expressed the Mer+ phenotype did not differ significantly in their radiosensitivity as compared to cells that were repair deficient (Mer-) and sensitive to nitrosoureas. Initial clinical follow-up suggests that factors in addition to inherent tumor cell radiosensitivity, such as performance status and age, continue to be the most important determinants of the response of patients with primary brain tumors to radiotherapy.

Glutathione levels and chemosensitizing effects of buthionine sulfoximine in human malignant glioma cells

Biopsy samples and cultured cells derived from them were obtained from 39 patients with malignant glioma and were analyzed for 1) glutathione (GSH) content; 2) sensitivity to 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and/or nitrogen mustard (HN2) treatment and 3) the effect of buthionine sulfoximine (BSO) treatment on BCNU and/or HN2 cytotoxicity. The average GSH concentration of biopsy specimens was lower than those of cultured cells (2.36 +/- 0.44 vs. 11.42 +/- 2.32 nmol/10(6) cells). While some of the tumor specimens were sensitive to either BCNU or HN2, the majority were resistant to both. However, 8 of 23 tumors tested showed enhanced sensitivity to BCNU following treatment with BSO. Five of 17 tumors were similarly sensitized to HN2 by BSO. These results suggest that BSO chemosensitization may be of value for certain patients and that screening assays may help identify treatment-sensitive individuals.

2-Nitroimidazole potentiation of nitrosourea induced cytotoxicity in subcutaneous implants of rat 9L brain tumor cells

To determine if the 2-nitroimidazole (2-NI) and the nitrosourea (NU) in a brain tumor chemopotentiation trial should be selected on the basis of known structure-activity relationships (electron affinity, lipophilicity, alkylating activity, carbamoylating activity), s.c. implants of rat 9L brain tumor cells were treated with combinations of misonidazole (MISO) or etanidazole (SR-2508) administered under oxic and hypoxic conditions, and BCNU, CCNU or chlorozotocin (CLZ) administered under oxic conditions. Cell kill was assessed by an in vivo to in vitro colony formation assay. To mimic the 'preincubation effect', the 2-NI was injected i.p., and 30 min later the tumor was clamped. After 2 hr, the clamp was released, and the NU administered immediately. MISO (2.5 mmole/kg) and SR-2508 (3.75 mmole/kg) reached the same peak tumor concentration in 30 min. Both 2-NIs were metabolized at the same rate in the clamped tumors; however, metabolism of the 2-NIs by hypoxic cells over the 2 hr clamping period did not produce any measurable s.c. 9L cell kill. The relative effectiveness of the NUs for killing oxic s.c. 9L tumor cells was: BCNU greater than CCNU greater than CLZ. Clamping the tumor prior to NU administration did not change the NU cytotoxicity. No potentiation of the NU cytotoxicity by the 2-NIs was observed in oxic tumors. Although metabolism of MISO by hypoxic cells did not result in potentiation of CLZ cytotoxicity at any dose, it resulted in potentiation of BCNU cytotoxicity at all doses and CCNU cytotoxicity at high doses.(ABSTRACT TRUNCATED AT 250 WORDS)

Cisplatin and etoposide combination therapy for primary glial tumors: preliminary results

In this preliminary trial we studied 29 patients with primary malignant glial tumors to investigate the effectiveness of cisplatin combined with etoposide on these tumors. Hyperfractionated radiation therapy was given in the course of chemotherapy. The time to tumor progression in these glioblastoma multiforme (GBM) patients encouraged us to continue this treatment in a phase III study.