MR-Guided Focused Ultrasound Used To Treat Bone Pain Caused by Bone Metastases

Using a new system, clinicians can utilize magnetic resonance imaging (MRI) to visualize the patient's anatomy and then aim focused ultrasound waves at the tumor to thermally ablate, or destroy it.

MRI allows the clinician to monitor and continuously adjust the treatment in real time. The patient is consciously sedated to alleviate pain and minimize motion. Due to the high acoustic absorption and low thermal conductivity of the bone cortex, it is possible to use a low level of energy and still achieve a localized heating effect while minimizing damage to adjacent tissue.

InSightec, Ltd. (Tirat Carmel, Israel) reported that the U.S. Food and Drug Administration (FDA) has approved an Investigational Device Exemptions (IDE) application that allows the company to launch a phase III pivotal study to determine if its ExAblate incisionless surgery system can safely and effectively reduce the pain associated with bone metastases in patients who have failed to respond to radiation therapy.

The non-invasive, ionized radiation-free MR-guided focused ultrasound (MRgFUS) system was approved to treat women suffering from symptomatic uterine fibroids in 2004. Over 3,500 women have already undergone treatment with ExAblate worldwide.

"Pain from tumors that have spread to the bone is the most common kind of pain for cancer patients,” noted Dr. Mark Hurwitz of the Dana-Farber/Brigham & Women's Cancer Center at Harvard Medical School (Boston, MA, USA). "While maintaining quality of life for patients with advanced cancer is a top priority, current palliative treatments have several limitations. When pain persists or recurs after palliative radiation, options are often limited as many patients are too weak to withstand invasive procedures to quell their pain. The ExAblate treatment has shown promising efficacy and safety results in feasibility studies. We look forward to participating in this pivotal study which could provide us with a non-invasive and effective way to improve late-stage cancer patients' quality of life.”

Bone is the third most common tissue to which cancer spreads, after the lungs and liver. Almost all patients with metastatic prostate cancer have skeletal metastases, and in breast cancer, bone is the second most common site of metastatic spread, affecting 90% of patients with progressive breast cancer. Most cancer patients suffer from pain; controlling it and managing its symptoms are important treatment goals.

Current treatment options for pain control consist of systemic therapy (analgesics, chemotherapy, hormonal therapy, and bisphosphonates) and local treatments (radiation, surgery and more recently, radiofrequency ablation [RFA]). InSightec expects to enroll 148 subjects with bone metastases who did not respond to radiation treatments into the study, which is expected to take place at 15 centers throughout the United States and internationally. The company is in the process of obtaining Institutional Review Board (IRB) approval from each of these sites.

The ExAblate 2000 system received the European CE Mark certification for pain palliation of bone metastases in June. In clinical studies, which supported the CE mark, the majority of patients reported pain relief within days of treatment.

The ExAblate 2000 is the first system to use the breakthrough MRgFUS technology that combines MRI--to visualize the body anatomy, plan and monitor treatment outcome in real time--and high intensity focused ultrasound to thermally ablate tumors inside the body non-invasively. MR thermometry, provided uniquely by the system, allows the physician to control and adjust the treatment in real time to ensure that the targeted tumor is fully treated and surrounding tissue is spared.


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