Cancer Pain Eased by MR-Guided, Focused Ultrasound Ablation Therapy

Patients with cancer that has metastasized to their bones are frequently treated with radiation therapy to reduce pain. But if that treatment does not work, or cannot be used again, a second, effective alternative, called magnetic resonance image-guided focused ultrasound (MRIgFU) ablation therapy, now exists.

The findings on the new therapy were presented in June 2013 at the annual meeting of the American Society of Clinical Oncology (ASCO), held in Chicago (IL, USA). Mark Hurwitz, MD, director of thermal oncology for the department of radiation oncology at Thomas Jefferson University (Philadelphia, PA, USA) and Hospital, reported that the treatment, MRIgFU ablation therapy, considerably decreases pain in 67% of patients who received the treatment. The device, known as ExAblate, uses many small ultrasound beams designed to converge on a tumor within bone, heat it, and destroy it.

“Pain is a common, often debilitating symptom of the spread of cancer to bones. We are pleased to now have a second therapy that can improve a patient’s enjoyment of life,” said Dr. Hurwitz, who led the clinical trial. A number of tumors metastasize to bones, and a substantial amount of patients live for years with these metastases, which can have a profound impact on a patient's quality of life, he added.

The findings of the trial led to approval of ExAblate last October by the US Food and Drug Administration (FDA) as second-line therapy for palliation of painful metastatic bone tumors. The first-line therapy is typically radiotherapy.

“The response to ExAblate was as good as radiotherapy, which was notable because it is very unusual to see a second-line treatment with a response rate that is as high as first-line therapy,” Dr. Hurwitz stated. He added that use of ExAblate offers several advantages compared to other ablative therapies. “It is noninvasive and provides more detailed anatomic information so that we can visualize the complete beam path to make sure that critical structures such as vessels and nerves are not in the way,” Dr. Hurwitz stated. “We are also able to monitor the temperature in the tumor as well as in nearby normal tissues so that we do not inadvertently heat normal organs and tissues.”

ExAblate has also been approved for treatment of uterine fibroids. The study led by Dr. Hurwitz is a multicenter, randomized, and placebo-controlled phase three clinical trial. The 142 patients enrolled could either not undergo, or had not responded to, radiation treatment. Three months after ExAblate therapy, 67% of treated patients reported significant improvement in pain, compared to 21% in the placebo arm. They typically rated their pain as “much improved” or “very much improved,” Dr. Hurwitz said.

A quality of life assessment in addition measured significant improvement. “The treatment is given just once, and a response occurs within days,” Dr. Hurwitz noted. “There are a lot of patients who could potentially benefit from MR guided focused ultrasound.”

The clinical trial was sponsored by Insightec, Ltd. (Tirat Carmel, Israel), who developed the ExAblate technology.

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Thomas Jefferson University
Insightec