SIR: Radiofrequency Ablates Pain of Benign Bone Tumor

SEATTLE, March 5 -- Radiofrequency ablation eliminates the debilitating bone pain of benign bone tumors without the risks associated with surgery, researchers here said.

Among 22 patients with osteoid osteoma, 19 (86%) left the hospital in hours with only a Band-Aid to show where the pain had been, said Eran Hayeems, M.D., of the University Health Network and Mount Sinai Hospital in Toronto.

At six months, 91% had complete resolution of pain, he reported here at the Society of Interventional Radiology meeting.

Osteoid osteoma is a poorly understood benign tumor that typically strikes children and adolescents and causes debilitating pain, particularly at night.

The traditional treatment is to surgically remove the small, usually 0.5 to 1 cm diameter growth along with about a 5 cm margin of bone around it. Patients typically have a two to three day hospital stay then months of convalescence and are at risk for complications, such as infection.

In contrast, radiofrequency involves inserting a probe through the skin under computed tomography imaging guidance and heating the tumor to about 80 to 90 Celsius. In the study, the procedure was done on an outpatient basis and no complications were reported.

The study included all 26 patients treated for osteoid osteoma at a single center from September 2004 to July 2006.

Most of the patients were young males (19 male, mean age 29, range 17 to 62). The majority of tumors were in the leg or pelvis (23), though there were three in the upper extremity or scapula. General anesthesia was used for 15 patients while three had general anesthesia combined with a nerve block and eight had epidural anesthesia.

All the procedures were technically successful with CT images showing that the ablation probe was placed in the lesion. The clinical findings included:

• No periprocedural or post procedure complications,
• Immediate resolution of pain for 86% (19 of 22 with follow-up) after the procedure whereas 14% (three patients) had no significant reduction in pain,
• Immediate resolution of pain and no recurrence through six months of follow-up for the one patient who had repeat ablation when pain continued after the initial treatment, and
• No evidence of growth of the tumor for seven of eight (88%) patients who underwent gadolinium-enhanced magnetic resonance imaging at one month follow-up (the one patient who underwent repeat ablation had evidence of enhancement after the first procedure).

"It's a cool procedure because the effect is so immediate and permanent," Dr. Hayeems said, and added that there is no down time so "they can go running afterward, they can do whatever they want."

While the study is not the first to show that radiofrequency ablation has good outcomes for osteoid osteoma, it is an important confirmatory study, said Robert L. Vogelzang, M.D., Northwestern Memorial Hospital in Chicago, who commented on the study.

"This makes it the treatment of choice in my opinion," he said.

He noted that re-treatment may be more difficult with surgery. Since the lesions are so small, they are hard to see during surgery and may be missed 10% to 15% of the time, he said.

Osteoid osteomas account for about 10% of bone cancers, which makes them relatively rare. Left untreated, they typically disappear within five to six years obliterated by new bone growth.

However, they are not without significant consequences for patients, said Kamran Ahrar, M.D., of the M.D. Anderson Cancer Center in Houston, who also commented on the study.

The characteristic pain associated with the tumors can be masked with nonsteroidal anti-inflammatory drugs, but long-term use of over-the-counter analgesics may cause gastric or other problems. The tumors may cause growth deformities and disuse atrophy as well, he said.

Dr. Ahrar agreed that radiofrequency ablation is "the new treatment of choice."

"I think that's the consensus in tertiary-care centers," he added. "Surgery in a growing child with growing bones is really something you want to avoid."

Another advantage of treating with the minimally invasive technique is price, Dr. Hayeems said. He estimated the price of radiofrequency ablation at about ,000 compared with tens of thousands for surgery.

However, tumors in the spine or near a blood vessel or nerve may still need to be treated with surgery, he said.