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Nov. 28, 2001 |
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Using radio waves to kill tumors CHICAGO -- Nov. 28, 2001 -- Zapping tumors with high-energy radio waves appears to offer a promising alternative to surgery for kidney cancer patients, according to a trio of studies presented this week at the annual meeting of the Radiological Society of North America. The studies conducted in Cleveland, Boston and Bethesda, Md. all use a similar approach called radio frequency ablation to direct radio waves guided with pinpoint accuracy by magnetic resonance imaging to essentially boil tumors to death. 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). The new technique offers a treatment option for patients who are not surgical candidates. At present, RF ablation as it is called, is offered primarily to patients who are not surgical candidates, but Dr. Jonathan S. Lewin of the University Hospitals of Cleveland and Case Western Reserve University says the initial results have been so encouraging that that the procedure soon may become a first-line treatment option for kidney cancer. "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 Lewin in a press release. "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, high-energy radio waves are delivered to the tumor through a small specially-designed titanium needle or stainless steel instruments which are not magnetic with an electrode on the tip. The needle pierces the skin and is inserted directly into the tumor under magnetic resonance (MR) imaging guidance to the tumor. 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 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. In a small 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). After an average follow-up period of 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 cm (1-1/2in.) or less and either were not candidates for surgery or refused surgery. Dr. Debra Gervais of Massachusetts General Hospital in Boston reported similar findings. Gervais and her colleagues treated 42 tumors in 34 patients, destroying 36 tumors completely and partially destroying the other six. In a National Institutes of Health study in Bethesda, Dr. Bradford Wood reported that 40 tumors in 33 patients were treated with RF ablation. After a follow-up ranging from 2 to 24 months, the researchers reported that 70 percent to 90 percent of the tumors were totally destroyed. "Magnetic resonance imaging is more sensitive than other scanning methods and can monitor the results of tumor destruction immediately, " said 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." The researchers also noted that the procedure is generally less expensive, safer and easier for patients than surgery. |
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