ScienceDaily (Apr. 11, 2005) — Pain from cancer that has spread to the bone can be effectively diminished with a new treatment that freezes the cancerous areas, Mayo Clinic researchers reported today at the 30th Annual Scientific Meeting of the Society of Interventional Radiology in New Orleans.

The treatment can provide a higher quality of life to patients whose activities are greatly limited because of the debilitating pain, says Matthew Callstrom, M.D., Ph.D., a radiologist at Mayo Clinic in Rochester and the chief author of the abstract. Approximately 100,000 people develop cancer that spreads to the bone (metastasis) in the United States each year. This cancer often causes severe pain that is unrelieved by narcotics and other standard pain treatments. The new minimally invasive technique, cryoablation, uses extreme cold to freeze the tumor.

"For the many patients who have metastatic disease, radiation therapy and other therapies may fail over time or do not work at all," says Dr. Callstrom. "You can reduce the pain for patients with narcotics, but that often means they're sleeping through much of the day and get through the day from narcotic dose to narcotic dose. This has a significant impact on their quality of life.

"I have a patient who wasn't part of this trial, but he was basically unable to do anything, because of his pain," says Dr. Callstrom. "We treated him with cryoablation three weeks ago. He's a farmer and he just jumped back into life and is farming."

Dr. Callstrom said the treatment doesn't cure the disease, but gives patients a higher quality of life. "In the time they have, they come back and join the family," he says.

Cryoablation has been used for many years in the operating room, but now with smaller, insulated probes interventional radiologists can provide the therapy through a small nick in the skin, without surgery or stitches. The physician uses computed tomography (CT) and ultrasound imaging to guide up to eight probes through the skin into the tumor of the patient, who is under anesthesia. The "ice ball" area that is created around the probe is visible with CT imaging, grows in size and destroys the frozen tumor cells.

This is the first prospective trial to evaluate the safety and efficacy of cryoablation through the skin to reduce painful metastatic lesions involving bone. These interim results in 13 patients show that pain relief is significant, and the treatment can be safely performed. Of the 13 patients who have been treated, 85 percent reported at least a three-point drop (on a scale of one to ten) in their worst pain. The study is ongoing and a total of 30 adult patients are planned for enrollment.

Dr. Callstrom says cryoablation offers greater precision than radiofrequency ablation, which uses heat. "You can't see precisely where the heat is being delivered in the tissue, so if you try to ablate a difficult area, you have to worry when you're near critical structures like the spinal cord, blood vessels or organs," says Dr. Callstrom. "With cryoablation, we can see the sharp line of the ice and take it right up to the critical structure and not harm it."

The purpose of treating painful bone tumors is to reduce pain and improve quality of life. Radiation treatments reduce pain in approximately 70 percent of patients, but the pain often returns or increases over time, and further radiation therapy is often not possible because it would damage healthy tissue. In addition, radiation therapy can take as long as 20 weeks to work.

"Cryoablation appears to offer some significant benefits," concludes Dr. Callstrom. "It can be done without surgery, and recovery time is therefore shorter, which is important for these patients who are terminally ill. The treatment works within a few weeks, is well tolerated and can be repeated if needed. It is a promising approach to give these patients a better quality of life in the time they have remaining."

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Adapted from materials provided by Mayo Clinic.

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