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CADTH » Search All Products » Environmental Scanning » Health Technology Update » Issue 8, January 2008 » The Treatment of Cancer Pain from Bone Metastases Using ExAblate® (Magnetic Resonance-Guided Focused Ultrasound)

The Treatment of Cancer Pain from Bone Metastases Using ExAblate® (Magnetic Resonance-Guided Focused Ultrasound)

Pain from bone metastases is often severe and can seriously decrease quality of life.


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Once the MRI scanner has provided a three-dimensional image of the target, the ExAblate® transducer delivers high intensity focused ultrasound to the site.

Photo courtesy of InSightec Ltd.

ExAblate® 2000 is a thermal heating device that delivers high intensity focused ultrasound waves to kill cells at a precise focal point without damaging adjacent healthy tissue. Currently used to treat uterine fibroids, this non-invasive procedure is being investigated for the palliation of painful bone metastases in patients who do not respond to other treatments.

How It Works

ExAblate is used in combination with magnetic resonance imaging (MRI) to identify and monitor the precise location of the painful bone lesions. Once the lesion is identified, ExAblate delivers a beam of high intensity focused ultrasound to the target, raising the temperature sufficiently to cause tissue destruction. The precise mechanism of analgesia is unknown, but immediate pain relief may be due to the destruction of nerve tissue, while continued analgesia may result from a decrease in tumour mass and subsequent pressure on the bone.[1]

The treatment takes approximately 80 minutes and is performed in an outpatient clinic.[1] Patients are given intravenous sedation and analgesia to prevent movement during the procedure. Potential complications of ExAblate treatment include superficial skin burns and thermal damage to adjacent heat-sensitive organs.[2]

Who Might Benefit

Bone metastases are common in cancer patients. Almost all patients with metastatic prostate cancer have tumours that have spread to the bone.[3] In breast cancer, bone is the second most common site of metastases, affecting 90% of patients with progressive breast cancer.[1]

Early Evidence

The first feasibility study included 13 patients.[1] Ten patients reported reductions in pain intensity (as measured by a Visual Analog Scale) and medication use during a mean follow-up period of two months. In most cases, pain reduction was noted as early as three days following ExAblate treatment. Some patients reported a small increase in pain in the immediate post-procedural period, but this pain subsided shortly after. One patient was unable to tolerate the ultrasound-induced pain and treatment was stopped. Two patients died (due to disease progression) within the first month after treatment.[1]

A second feasibility study of ExAblate for pain palliation is underway at Toronto’s Mount Sinai Hospital.

Future Developments

MRI-guided high intensity focused ultrasound is also being evaluated for its ability to destroy malignant cells in cancers of the breast, bone, liver, kidney, pancreas, uterus, and prostate.[4]

Regulatory Status

The ExAblate 2000 system (InSightec Ltd., Israel) was licensed by Health Canada in 2007 for the treatment of uterine fibroids.

Cost

According to InSightec, the ExAblate 2000 system costs approximately US$1 million. This does not include the cost of the MRI scanner used during the procedure.

References

[1] Catane R, et al. Ann Oncol 2007;18(1):163-7.
[2] Catane R, et al. ExAblate 2000 Clin Rep 2006;5(1):1-8. Available: http://www.insightec.com/SIP_STORAGE/files/1/261.pdf
[3] Goh P, et al. Curr Oncol 2007;14(1):9-12.
[4] ter Harr HG, et al. Int J Hyperthermia 2007;23(2):89-104.