A treatment called radiofrequency ablation zaps kidney cancers with electrical currents, causing the tumors to disintegrate without the need for surgery, a new study says.
"It's very promising for small tumors and tumors growing outside of the kidney," says Dr. Debra Gervais, director of Interventional Radiology at Massachusetts General Hospital in Boston. "It's a little more problematic if the tumors are larger or close to a vital structure or organ."
Gervais and her colleagues tried the technique on 42 relatively small, cancerous tumors in 34 patients. The tumors, which ranged in size from 1 centimeter to 9 centimeters, had not metastasized -- or spread -- to other organs.
The researchers were able to eliminate 36 of the tumors completely, including all those, regardless of size, located on the surface of the kidney.
Larger tumors (3 centimeters or bigger) deep inside the kidney were more difficult to treat. The researchers were able to eliminate about half of them.
Two of the 11 larger, centrally located tumors were eliminated in a single session. Three others were eliminated with only one additional visit.
The study, the most extensive to date on radiofrequency ablation and kidney cancer, appears in the February issue of Radiology.
After three and a half years, no one in the study had a recurrence of kidney cancer.
"It's a very promising application of this technology," says Dr. Bradford Wood, an interventional radiologist at the National Institutes of Health who was involved with some of the earliest studies on radiofrequency ablation and cancer.
The American Cancer Society estimates there will be approximately 31,900 new cases of kidney cancer in the United States in 2003. The five-year survival rate for people diagnosed with renal cell carcinoma is approximately 60 percent.
The current standard treatment is surgical removal of the kidney, Gervais says.
In radiofrequency ablation, an insulated needle is inserted into the tumor mass, using a CT scan, ultrasound or other imaging technique to guide it.
An electrical current from the needle heats up and burns the cancer tumor, turning it into a mass of dead scar tissue, says Gervais, lead author of the study and an assistant professor of radiology at Harvard Medical School.
For that reason, radiofrequency ablation can't be used to treat all cancers, Gervais says. Doctors have to be very careful not to damage surrounding organs or tissues.
The insulating fat surrounding the kidney allows high temperature ablation on tumors protruding from the kidney. Tumors deep inside the kidney are more difficult to eliminate because ablation temperatures must be controlled to avoid damaging the rest of the kidney, she says.
For now, Gervais limits radiofrequency ablation to patients who aren't good candidates for surgery because of kidney disease, or because they only have one functioning kidney.
Doctors are experimenting with radiofrequency ablation on other types of cancers.
The procedure was first used in the 1980s on benign, painful bone tumors, Gervais says.
The technique is also used on some liver cancers, lung cancer and to treat a type of heart arrhythmia.
Wood says he has used radiofrequency ablation on tumors from "the neck to the thigh."
One newer use of the technique is to relieve pain in people who are dying from cancer, Wood says. Cancerous tumors, as they grow, can push on other structures of the body, causing pain.
In some cases, he can use radiofrequency ablation to reduce the size of the tumor, easing the discomfort.
For example, he and his colleagues used the technique in a woman who had a large tumor in the wall of her pelvis that was causing her extreme pain and forcing her to urinate every hour.
"She only lived another nine months, but reducing the size of the tumor allowed her to get off much of her pain medication and enjoy the last months with her family," Wood says.