Freezing tumors eases cancer pain in study

By Julie SteenhuysenTue Nov 27, 5:05 PM ET
Freezing tumors may help relieve the extreme pain of cancer that has spread to the bone, which is often untouched by narcotics or radiation, U.S. researchers said on Tuesday.
This freezing process, called cryoablation, is often used to destroy kidney, prostate and other tumors, but researchers at the Mayo Clinic in Rochester, Minnesota, found it eased cancer pain in 80 percent of patients in a small study, and the effect lasted for up to six months.
About 100,000 people in the United States each year have cancer that metastasizes, or spreads, to the bones. Radiation therapy is the most common treatment for localized pain in metastatic cancer.
"Two key parts of this study are that the reduction in pain lasts and their quality of life improves after receiving the treatment," Dr. Matthew Callstrom, a radiologist, said in a statement. He presented his results at the annual meeting of the Radiological Society of North America in Chicago.
The study, funded by medical device maker Endocare Inc, involved 34 patients who had failed to find relief from conventional pain management treatments or refused them.
They had different primary cancers, including colorectal, renal cell, ovarian, thyroid and melanoma -- all of which had spread to the bone.
Doctors used CT imaging scanners to guide tiny, needle-like probes to the tumor. Argon gas was then injected through a tiny tube into a larger chamber in the probe, causing it to become cold enough to freeze the tumor.
"You have very good control and you can see exactly what you are doing," Callstrom said in a telephone interview.
Patients in the study started out with an average pain score of 7.2 on a scale of 10, which is considered moderately severe. That was reduced by roughly half (about 3.6) eight weeks later. For patients followed for 24 weeks, the score dropped to an average of 1.7.
"That's a pretty good drop in their pain," said Callstrom, who was not paid by Endocare.
"The technique is very well tolerated. It does not increase pain and you can do it with very high precision."
He and colleagues plan to study the pain management approach in a larger study funded by Endocare and the National Cancer Institute, comparing cryoablation and radiation.