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Putting Cancer in Deep Freeze

Cryosurgery gets boost from chemotherapy in treating prostate, liver cancer

FRIDAY, May 17, 2002 (HealthDayNews) -- Doctors have been freezing malignant tumors for years with cryosurgery, but hardy cancer cells sometimes resist the arctic blasts and stay inside the body to cause more trouble later.

Now researchers say a combination of cryosurgery and chemotherapy may wipe out all the malignant cells.

"Cryosurgery is a very effective method for treatment of cancer, and it will become more effective," predicts study author Boris Rubinsky, a professor of bioengineering and mechanical engineering at the University of California, Berkeley. "I anticipate that some doctors will use this procedure as soon as this study goes into print."

Doctors began to freeze tumors in the 1960s, but they were hampered by not being able to see inside the body. The procedure has become more common as scientists have developed probes that direct liquid nitrogen or argon gas to freeze tumors inside the body, and ultrasound machines now show doctors where they're going. Doctors use cryosurgery to treat prostate cancer and liver cancer. Experiments are being done on pancreatic cancer and bone cancer.

"You inject it into the tumor, and you keep freezing until the tumor is frozen," Rubinsky says. "The frozen tissue remains in the body, and the immune system removes it [if it is dead]."

However, there can be a big problem. The probes turn tumors into "ice balls," but the temperatures vary from the core (as low as 220 degrees below zero Fahrenheit) to the outer edges (as high as 40 degrees below zero Fahrenheit). So, some cells on the edges survive the cold.

Doctors often will freeze nearby healthy tissue to get at the edges of a tumor, but that technique can create its own problems because healthy nerves and muscles are damaged, and that can lead to incontinence or impotence.

Rubinsky and a colleague at France's Institut Gustave-Roussy tried to replicate what happens in humans by freezing skin cancer cells in test tubes and then treating them with bleomycin, a chemotherapy drug also known by the brand name Blenoxane. Their findings will appear in next week's British Journal of Cancer.

Numerous cancer cells remained after freezing, but subsequent treatment with bleomycin destroyed most or almost all of them, depending on how much of the drug was used.

The combination treatment works because the surviving cancer cells are weakened by their freezing and become more vulnerable to bleomycin, says Dr. Israel Barken, chairman and medical director of the Prostate Cancer Research and Education Foundation, which helped fund the research.

"It gives you the opportunity to be less aggressive with chemotherapy, so the tissue around [the tumor] won't get damaged," Barken says.

He cautions that animal studies must be done to determine the full effectiveness of the treatment. "This is a very preliminary stage," he notes.

But Rubinsky says that doctors can begin using the combination treatment immediately because the federal government has already approved cryosurgery and bleomycin for use separately to treat cancer.

"There is no impediment," he adds.

What To Do

Learn about the advantages and disadvantages of cryosurgery from the Crittendon Hospital Medical Center.

Learn more about prostate cancer from the American Cancer Society.

SOURCES: Boris Rubinsky, Ph.D., professor, bioengineering and mechanical engineering, University of California, Berkeley; Israel Barken, M.D., chairman and medical director, Prostate Cancer Research and Education Foundation, San Diego; May 20, 2002, British Journal of Cancer
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