Nov. 29, 2001 CHICAGO, November 27, 2001 -- Interventional radiologists are using the same kind of energy that puts sound into your radio to heat and kill tumors, an approach that is proving to be an increasingly promising treatment for kidney cancer. Guided with pinpoint accuracy under magnetic resonance imaging, the tools that deliver radio frequency (RF) waves essentially boil tumors to death.
Physicians and scientists at The Research Institute at University Hospitals of Cleveland and Case Western Reserve University reported promising results using this approach at the annual meeting this week of the Radiological Society of North America (RSNA) in Chicago. Similar findings in studies at Massachusetts General Hospital in Boston and the National Institutes of Health were also presented.
The standard of care for kidney cancer is surgical removal of either the entire affected kidney (nephrectomy) or only the cancerous portion of the kidney (partial nephrectomy or nephron-sparing surgery). For patients who are not surgical candidates, there is now a new treatment option – RF energy treatment, a minimally invasive approach. While at present RF ablation, as it is called, is offered mostly to patients who are not surgical candidates, encouraged by the initial results, researchers say that the procedure soon may become a first-line treatment option for kidney cancer.
“Although the protocol in general has been only to treat patients who aren’t good surgical candidates, there has been increasing interest in using it as a primary treatment, because surgical removal of part of the kidney is such a major procedure,” said Jonathan S. Lewin, M.D., Professor of Radiology, Oncology and Neurological Surgery, and Vice-chairman of Research and Academic Affairs, University Hospitals of Cleveland and Case Western Reserve University. “It is being used to treat prostate, breast, brain, liver and other types of cancers, and I see no reason why it couldn’t be used almost anywhere in the body.”
In RFA, radio frequency energy is fed to the tumor through a very small needle with an electrode on the tip. The needle pierces the skin and is inserted directly into the tumor under magnetic resonance (MR) imaging guidance. After 10 to 30 minutes of continuous contact with tumor tissue, the RF energy “cooks” a 1- to 3-inch diameter sphere, killing the tumor cells. A large area of the tumor can be treated by cooking overlapping spheres. The dead cells are not removed, but become scar tissue and eventually shrink. Typically, the outpatient procedure is performed while the patient is lightly sedated, and the patient may go home hours later, usually feeling minimal pain.
Researchers say the procedure is generally less expensive, safer and easier for patients than surgery.
In the phase II clinical trial at University Hospitals of Cleveland/Case Western Reserve University School of Medicine, the tumor was completely ablated in 10 of 11 patients (91 percent) treated with RF energy and there were no cancer recurrences in 9 of the 11 patients (82 percent). The average follow-up period was 14 months. One patient died of unrelated causes with no evidence of cancer, and another was suspected of having a recent local recurrence and likely will undergo RFA again. All 11 patients had tumors that measured 4 centimeters or less and either were not candidates for surgery or refused surgery.
“Magnetic resonance imaging is more sensitive than other scanning methods and can monitor the results of tumor destruction immediately, ” said Dr. Lewin. “In two-thirds of our patients, I saw residual tumor that was not ablated in the first pass and I could go back and ablate it then and there. With CT scans, for example, you can’t immediately see what was not ablated and you have to go back later and do another procedure.”
Dr. Lewin is one of the nation’s leading experts in interventional radiology, and has helped develop some of the tools required for use with magnetic resonance imaging. For several years, he has combined radiofrequency ablation techniques with MRI to eradicate kidney tumors. Using open MRI, which provides more comfortable surroundings to patients, doctors gain access to these abnormalities through a needle puncture. Using specially-designed titanium or stainless steel instruments which are not magnetic, doctors are guided by the MRI image to the site of the malignancy. They guide a titanium electrode to the tumor and generate enough heat to destroy the cancer cells.
"What used to be a bright white area of tumor becomes black, essentially a black hole of dead tumor tissue," says Dr. Lewin. "You can immediately see through the MRI image how much of the tumor is destroyed, how much is left, and how much further you need to go to completely eradicate the cancer." There is also no cumulative dose effect, as there is in radiation therapy, so patients can be treated repeatedly if the cancer returns to other sites.
Co-authors of the study being presented by Dr. Lewin are Cindy F. Connell, M.D., Ph.D., Jeffrey L. Duerk, Ph.D., Sherif G. Nour, M.D., Martin I. Resnick, M.D., and John R. Haaga, M.D.
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