By Ed Susman
CHICAGO, I.L. -- November 27, 2006 -- Minimally invasive procedures that turn metastatic cancer lesions into iceballs appears to effectively relieve pain among patients who have not had success with other analgesic modalities, researchers said here at the 92nd scientific assembly and annual meeting of the Radiological Society of North America (RSNA).
"The treatment is safe. The pain relief is dramatic and durable," said Matthew Callstrom, MD, PhD, assistant professor of radiology, Mayo Clinic college of Medicine, Rochester, Minnesota.
Dr. Callstrom reported in an oral presentation on November 26th that within 4 weeks of treatment 30% of the patients who were treated were free of pain and 68% of patients were able to report a 3-point decrease in pain scores on a validated pain score inventory.
"Our preliminary results suggest that cryoablation provides an alternative treatment for patients with painful metastatic disease," Dr. Callstrom said. "It is important to note that these are patients who have failed conventional therapies."
In the on-going clinical evaluation of cryoablation of painful metastases is designed to enroll a total of 30 patients with a variety of cancer metastases. He reported on 28 of those patients who have 2 to 24 weeks of follow-up.
The researchers scrutinized the ability of cryoablation to relieve pain rather compared with other methods, such as radiofrequency ablation. Dr. Callstrom said that while radiofrequency ablation is successful in reducing pain associated with cancer metastasis, it can take as long as 6 weeks for pain to be reduced to normal and in 70% of cases, pain actually increased immediately after treatment.
For enrollment in the trial, patients must have moderate to severe pain -- a score of 4 out of 10 on the Brief Pain Inventory in the previous 24-hour period, and have pain despite previous surgery, radiation, chemotherapy or combinations of these treatments. About 21% of the patients, however, had neither chemotherapy nor radiation upon entry into the study. Patients with spinal cord metastases were excluded.
"The iceball that is generated by the cryosurgery covered the entire metastasis and can be seen very easily with computer-assisted tomography monitoring," Dr. Callstrom demonstrated.
Upon entry into the study the average pain score was 7.5 -- an indicator of severe pain. That score was reduced an average of 3 points within 4 weeks (P <.0001), Dr. Callstrom said. "A reduction of 2 points is considered clinically meaningful," he noted. The pain reduction was also significant at 8 weeks, decreasing about another point, and was sustained at least as long as 24 weeks.
The study also evaluated quality of life status, looking at the effect of pain on activities of daily living. The improvement in quality of life reached statistical significance at 4 weeks (P =.0005) and at 8 weeks (P =.0007), he said. The interference scores were 5 out of 10 prior to the minimally invasive cryoablation procedure and decreased to between 1 and 2 after the treatment.
In the follow-up period there have been no major or minor complications reported, he said. The trial is being expanded into a multicenter study. Dr. Callstrom said his study is being supported by Endocare of Irvine, California.
[Presentation title: Percutaneous Cryotherapy Treatment of Painful Metastatic Disease Involving Bone: Ongoing Clinical Trial. Abstract SSA02-07]
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