A Study to Evaluate the Safety and Feasibility of Transcranial MRI-Guided Focused Ultrasound Surgery in the Treatment of Brain Tumors
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. MRIgFUS could play and important
role in ablating brain metastases in patients who have already been maximally radiated and
are otherwise without options.
Interventional
Endpoint Classification: Safety Study, Intervention Model: Single Group Assignment, Masking: Open Label, Primary Purpose: Treatment
Canada: Health Canada
BT003
NCT01473485
April 2011
April 2012
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