Moving targets and ghosts of the past: outcome measurement in brain tumour therapy

Fractionated stereotactic radiotherapy boost and weekly paclitaxel in malignant gliomas clinical and pharmacokinetics results

Management of Malignant Gliomas continues to be a challenge. We prospectively studied the role of adding weekly Paclitaxel to Fractionated Stereotactic Radiation Therapy (FSRT) in the treatment of Malignant Gliomas. Twenty-three Glioblastoma Multiforme and two Anaplastic Astrocytoma were studied. Patients received 46 Gy at 2 Gy/fraction followed by a boost utilizing FSRT at a fraction of 2.5 Gy for 8 fractions. Paclitaxel is delivered concomitantly at 150 mg/m(2) weekly for six cycles. Eighteen patients had pharmacokinetic assays of Paclitaxel levels. All patients were followed until death or for a maximum of 36 months. The overall survival of the whole group was 14 months. The median survival for RPA prognostic classes III, IV, V, and VI were 20, 14, 12, and 11 months. Higher survival (14 months) was noted in the subtherapeutic phenytoin level group compared to 10 months in the therapeutic group (P=0.271). No grade 4 CTCAE (version 3.0) toxicities were observed. Enhanced survival was demonstrated with gross tumor resection (20.8 months), KPS > or =80 (18.7 months) and age < or =60 years (27 months) as compared to subtotal resection or biopsy (12.1 months, P< 0.005), KPS < or =70 (10.8 months, P=0. 005) and older age > 60 (10.46 months, P=0.006), respectively. Our study suggests that: i) the use of weekly Paclitaxel and FSRT in Gliomas is well tolerated with a survival of 14 months; ii) the regimen resulted in improvement of survival of RPA classes IV, V, VI; and iii) the use of FSRT boost may be studied with other chemotherapeutic agents to see if superior results can be attained.

Intra-arterial drug delivery: a concise review

The therapeutic potential of intra-arterial (IA) drug delivery to the brain has received limited attention in the last decade. In the 1980s, efforts to treat brain tumors with IA chemotherapy, the leading application of this technology, yielded modest results. Poor control of tissue drug concentrations and the potential risk of permanent neurologic injury further prevented the wider use of IA drugs. Yet, IA drugs were anecdotally used for treating a wide spectrum of brain diseases. Recent advances in endovascular technology and the increased safety of angiographic procedures now compel us to reevaluate IA drug delivery. This review describes the pharmacologic principles, applications, and pitfalls of IA drug delivery to the brain.

Historical controls for phase II surgically based trials requiring gross total resection of glioblastoma multiforme

New treatments for patients with glioblastoma multiforme (GBM) are frequently tested in phase II surgically based clinical trials that require gross total resection (GTR). In order to determine efficacy in such single-arm phase II clinical trials, the results are often compared to those from a historical control group that is not limited to patients with GTR. Recursive partitioning analysis (RPA) can define risk groups within historical control groups; however, RPA analyses to date included patients irrespective of whether a patient had a GTR or not. To provide a more appropriate historical control group for surgically based trials requiring a GTR, we sought to determine survival for a group of patients with newly diagnosed GBM, all of who underwent GTR and were treated on prospective clinical trials. GTR was defined as removal of >90% of the enhancing mass, determined by postoperative magnetic resonance imaging. Of 893 patients with GBM treated during these trials, 153 underwent GTR. The median survival for the GTR group was 71 weeks (95% CI 65-76) which was better than those who did not have a GTR. Within the GTR group, the median age was 54 years (range 25-77 years), and median Karnofsky Performance Score was 90 (range 60-100). Considering only patients with GTR, age at diagnosis continued to be a statistically significant prognostic factor. Patients treated during surgically based phase II studies should be matched with a historical control group restricted to patients with similar pretreatment variables, including GTR.

GNOSIS: guidelines for neuro-oncology: standards for investigational studies--reporting of surgically based therapeutic clinical trials

We present guidelines to standardize the reporting of surgically based neuro-oncology trials. The guidelines are summarized in a checklist format that can be used as a framework from which to construct a surgically based trial. This manuscript follows and is taken in part from GNOSIS: Guidelines for neuro-oncology: Standards for investigational studies-reporting of phase 1 and phase 2 clinical trials [Chang SM, Reynolds SL, Butowski N, Lamborn KR, Buckner JC, Kaplan RS, Bigner DD (2005) Neuro-oncology 7:425-434].

GNOSIS: guidelines for neuro-oncology: standards for investigational studies-reporting of phase 1 and phase 2 clinical trials

We present guidelines to standardize the reporting of phase 1 and phase 2 neuro-oncology trials. The guidelines are also intended to assist with accurate interpretation of results from these trials, to facilitate the peer-review process, and to expedite the publication of important and accurate manuscripts. Our guidelines are summarized in a checklist format that can be used as a framework from which to construct a phase 1 or 2 clinical trial.

Linear Accelerator Radiosurgery in the Treatment of Brain Metastases

OBJECTIVE:

To review a 12-year experience treating metastatic brain disease with linear accelerator-based stereotactic radiosurgery (SRS).

METHODS:

We performed a retrospective analysis of all patients treated between 1989 and 2001 with linear accelerator radiosurgery for brain metastases. Patients were followed up both clinically and with imaging studies to document local control, regional control, and survival. Demographic data, dosing parameters, number of lesions, histology, history of whole-brain radiation therapy, and other factors were obtained prospectively. Cox proportional-hazards regression with multivariate and univariate analysis was performed with Stata 8.0 software.

RESULTS:

A total of 383 patients received SRS for brain metastases during the study interval. Median survival was 9 months. Patients with tumor-type melanoma or multiple metastatic lesions had decreased survival. Actuarial 1-year local control was 75%. Differences in regional control rates were not statistically significant between patients treated with SRS and whole-brain radiation therapy versus SRS alone.

CONCLUSION:

Radiosurgery is an effective and safe method for treating selected patients with brain metastases.

Review of microdialysis in brain tumors, from concept to application: first annual Carolyn Frye-Halloran symposium

In individuals with brain tumors, pharmacodynamic and pharmacokinetic studies of therapeutic agents have historically used analyses of drug concentrations in serum or cerebrospinal fluid, which unfortunately do not necessarily reflect concentrations within the tumor and adjacent brain. This review article introduces to neurological and medical oncologists, as well as pharmacologists, the application of microdialysis in monitoring drug metabolism and delivery within the fluid of the interstitial space of brain tumor and its surroundings. Microdialysis samples soluble molecules from the extracellular fluid via a semipermeable membrane at the tip of a probe. In the past decade, it has been used predominantly in neurointensive care in the setting of brain trauma, vasospasm, epilepsy,and intracerebral hemorrhage. At the first Carolyn Frye-Halloran Symposium held at Massachusetts General Hospital in March 2002, the concept of microdialysis was extended to specifically address its possible use in treating brain tumor patients. In doing so we provide a rationale for the use of this technology by a National Cancer Institute consortium, New Approaches to Brain Tumor Therapy, to measure levels of drugs in brain tissue as part of phase 1 trials.

Fractionated stereotactic radiotherapy boost after post-operative radiotherapy in patients with high-grade gliomas

PURPOSE

To determine the value and the toxicity of an additional fractionated stereotactic boost as used in the joint randomized EORTC-22972/MRC-BR10 study in patients with malignant gliomas.

MATERIALS AND METHODS

Seventeen patients (11 male, six female) with a high-grade glioma (two WHO III, 15 WHO IV) < or =4 cm in maximum diameter, with a good performance status (WHO > or =2), were treated with a fractionated stereotactic radiotherapy (SRT) boost to 20 Gy in four fractions following partial brain irradiation to a dose of 60 Gy in 30 fractions. This patient group was compared with historical data in a matched-pair analysis.

RESULTS

All patients were treated by conventional radiotherapy and a SRT boost (15 patients received 20 Gy and two patients 10 Gy). Acute side effects included fatigue (two), impairment of short-term memory (one) and worsening of pre-existing symptoms (one). No patient developed steroid dependence after SRT. One patient was re-operated for radiation necrosis. At a median follow-up of 25 months (9-50 months) 14 patients recurred locally. Survival was 77% at 1 year and 42% at 2 years; progression-free survival was 70% at 1 year and 35% at 2 years for all patients, respectively. Median survival for the whole patient group is 20 months. Comparison with a matched historical group showed a significantly better survival for the group treated with a stereotactic boost (P<0.0001).

CONCLUSION

A fractionated stereotactic boost after standard external beam radiotherapy in selected patients with high-grade glioma is feasible and well tolerated with low toxicity. Compared to historical data survival is significantly better with an additional SRT boost. However, its effectiveness has to be proven in a randomized trial.

Evidence-based neurosurgery

OBJECTIVE

The evidence-based medicine movement is gaining influence in many medical specialties. Although many think that clinical medicine always has been based on evidence, the discipline of evidence-based medicine places particular emphasis on a defined set of principles of critical analysis of individual research reports, methodologically rigorous synthesis of multiple reports, and the collection and dissemination of evidence repositories that allow rapid application of evidence in practice. This article provides a selective introduction to the discipline of evidence-based medicine as it applies to neurological surgery.

METHODS

The vast literature on evidence-based medicine has been reviewed selectively to identify resources that are readable, accessible, and relevant to neurosurgery.

RESULTS

The history, concepts, and techniques of evidence-based medicine are presented in brief, and educational and methodological resources, as well as evidence repositories, are introduced.

CONCLUSION

The techniques of evidence-based medicine are relevant to neurological surgery. There is a relatively large repository of critically analyzed and summarized evidence that is useful to the neurosurgical practitioner. Familiarity with these techniques and repositories can help the neurosurgeon bring the best available evidence to bear on the care of individual patients.