Brain tumors are the most common solid tumors and they increase with age.
The incidence rate of all primary non–malignant and malignant brain and central nervous system tumors in the US is 19.3 cases per 100,000 person–years. 60,000 new cases of primary brain cancer are diagnosed annually in the US and 400,000 around the world.
Treatments
Despite progress made in many cancer treatments, brain tumors remain an extraordinary challenge. Due to the inherent risks with associated surgical resection and radiotherapy, combined with the aggressiveness of many CNS tumors and the difficulty in delivering anticancer drugs to the brain, the prognosis for patients with many types of brain tumors remains grim. New and less invasive alternatives to existing procedures are desperately needed.
MRgFUS for tumor ablation
Transcranial magnetic resonance imaging-guided focused ultrasound surgery offers a potential noninvasive alternative to surgical resection. The method combines a hemispherical phased-array transducer and patient-specific treatment planning based on acoustic models with feedback control based on magnetic resonance temperature imaging to overcome the effects of the cranium and allow for controlled and precise thermal ablation in the brain. ). It can be used to destroy tumors with little or no effects to the surrounding tissue, producing immediate and localized thermal coagulation. It can be used along with, potentially synergistically with, radiotherapy or chemotherapy. Thermal ablation, which does not utilize ionizing radiation, can also be reapplied in the case of recurrence.
Clinical Results
3 glioblastoma patients were treated in a Phase I clinical feasibility study of transcranial magnetic resonance imaging-guided focused ultrasound surgery. It was possible to focus an ultrasound beam transcranially into the brain and to visualize the heating with magnetic resonance temperature imaging. Extrapolation of the temperature measurements at the focus and on the brain surface suggests that thermal ablation will be possible with this device without overheating the brain surface, with some possible limitation on the treatment envelope.
Source: Ram Z, Cohen ZR, Har Nof S, Tal S, Faibel M, Nass D, Maier SE, Hadani M, Mardor Y. MR guided Focused Ultrasound Surgery (MRgFUS) for Brain Tumor Therapy: Initial Clinical Experience, Neurosurgery.
Ongoing Clinical Trials
ExAblate (Magnetic Resonance-guided Focused Ultrasound Surgery) Treatment of Brain Tumors
An ongoing clinical study is currently taking place at Sunnybrook Health Science Centre, Toronto, Canada.
The purpose of this study is to evaluate the Safety and Feasibility of Transcranial MRI-Guided Focused Ultrasound Surgery in the Treatment of Brain Tumors.
Contact information:
(Please refer to this study by its ClinicalTrials.gov identifier: NCT01473485 )
Sunnybrook Health Science Centre, Toronto, Canada
Julie Gundry 416-480-6100, ext 7362
julie.gundry@sunnybrook.ca
Principal Investigator: Todd Mainprize, MD
Description
Although the initial treatment of malignant gliomas is well established, the best treatment for progressive disease remains undefined. Patients with newly diagnosed gliomas are typically treated with surgery followed by conformal radiation and concomitant chemotherapy. Even though these tumors are not curable, prolonged survival can be achieved in selected patients. Despite improved multimodal therapies, almost all of the patients experience recurrence at the site of the primary tumor where they have already received maximal surgical resection and radiation therapy. Typically, these patients have a life expectancy of approximately 6 months, with less than a third of patients alive at one year. Salvage therapy for these patients usually take the form of various systemic chemotherapeutic agents because localized therapies such as reirradiation may not be possible in the previously irradiated site. As progressive disease has very poor response rates to current systemic therapies, efforts to define the role of novel local therapies, such as MR guided focused ultrasound (MRgFUS), is necessary.
There are very few local therapy options for progressive gliomas. Traditionally, reirradiation and surgery are considered last resort treatments for symptomatic recurrence. In the initial treatment of gliomas, the tumor and surrounding brain receive near tolerance doses and usually preclude a second course of radiation therapy. If clinically advisable and feasible, a second operation may be undertaken but is usually reserved for younger patients with a good neurological status who are developing neurological symptoms related to the mass effect of the tumor. The use of MR guided focused ultrasound represents a new, noninvasive therapeutic option that overcomes some of the limitations of secondary surgery or reirradiation and provides the patient with an option for local ablative therapy. The lesioning of the tumor is done accurately under MRI guidance with real-time monitoring of the ablative ultrasonic hyperthermia. As the cytotoxic affects are due to hyperthermia, there is no cumulative radiation affect which limits the use of radiotherapy in recurrent disease. The potential benefits for the patient include local control of the disease/tumor, and prolonging the time to subsequent salvage therapies.
A similar situation exists for brain metastases. Historically, the development of brain metastases was considered a terminal event, however, with better local therapies as well a systemic therapies, patients are living longer. Initial management of patients with brain metastases usually involves surgery, whole brain radiation, radiosurgery or a combination of these modalities depending on the clinical situation. The goal of treating brain metastases is to prevent the patient from succumbing to CNS disease. As improved systemic therapy has lengthened the survival of patients with metastatic tumors, more patients are surviving and developing recurrent or progressive metastatic CNS disease. Progressive disease usually requires more local therapies as chemotherapeutic agents do not adequately cross the blood brain barrier to have a large impact on CNS metastases. MRgFUS could play and important role in ablating brain metastases in patients who have already been maximally radiated and are otherwise without options.
Click here for the brain tumors study on Clinical Trials.gov.
Support Organizations
National Brain Tumor Society
American Brain Tumor Association
International Brain Tumor Alliance
Association of People Affected by Brain Tumors in Spain (ASAT)
