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Microwaves aim to shrink tumors

Medicine | IN THE LAB

Using military defense technology, scientists are targeting breast cancer before surgery.

May 05, 2003|Shari Roan | Times Staff Writer

Lumpectomy to remove small breast tumors is an important option for women, allowing many to survive cancer and keep their breasts. But one drawback to lumpectomy -- of which many women are unaware -- is that one-fourth to one-half of patients have to return for a second surgery to remove more tissue.

Researchers say they are fast developing tools that could dramatically reduce need for a second surgery, called "re-excision."

Moreover, their work could lead to new treatments for even larger tumors, which often require mastectomies.

Using microwave technology developed for a space-based missile defense system, doctors at the Research and Education Institute at Harbor-UCLA Medical Center are shrinking tumors before surgery. Such shrinkage helps eliminate stray cancer cells and minimizes damage to the breast during lumpectomy.

"We're trying to kill the cancer cells with a less invasive technique," says Dr. Hernan Vargas, director of the Breast Clinic at Harbor-UCLA Medical Center. "The ideal treatment for cancer is to kill the bad cells without damaging the normal cells."

In lumpectomy, doctors make a small opening in the breast and remove the tumor along with a 1- to 2-centimeter margin of healthy tissue. That healthy tissue is later examined under a microscope for evidence of cancer. If cancer cells are present, more tissue is removed.

"The question for the surgeon is how much tissue to take out," Vargas says. "You want to leave enough so the woman has a breast with a normal shape and look. But we don't want the cancer to come back."

Even when the margins are "clean," breast cancer recurs in some women, he says.

The technique Vargas and others are testing, called Adaptive Phased Array microwave technology, could dramatically reduce re-excision rates and lessen the chances of cancer recurrence. It works by targeting breast tissue with high water content (the cancer cells) while sparing tissue with low-water content (healthy cells).

The treatment, which is performed a few weeks before the lumpectomy, is fairly quick and low-risk. A small needle with a thermometer is inserted through the skin into the tumor. More thermometers are placed on the surface of the breast. A cooling system protects the skin while the microwave device heats the tumor. The procedure takes about 20 minutes and requires local anesthesia.

In a recent study, no cancer cells were found outside the lump in 24 of 25 women. The therapy also shrank the tumors in many women, Vargas says.

In 80% of the cases, tumor cells were damaged by the therapy, and some patients who had higher doses of microwave therapy had much of the cancer destroyed before surgery. Two patients suffered mild burns.

Researchers at Harbor-UCLA and several other sites are conducting a similar study of 500 patients. A separate study of several hundred women with more advanced breast cancers, which typically require mastectomy, also is underway. They will undergo chemotherapy and microwave therapy before surgery to see if tumors can be shrunk enough to permit lumpectomy instead of mastectomy. Both trials are being conducted by Celsion Corp. of Columbia, Md., which makes the device.

The long-term goal of the research, says Vargas, is to destroy tumors before surgery.

Scientists also are testing radio frequency waves and cryotherapy to shrink tumors and are combining these heating and freezing therapies with chemotherapy and new cancer drugs.

"We see these minimally invasive treatments as part of the evolution of treating breast cancer," he says. "The goal for the future is that we'll be able to treat cancer without surgery at all."

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About lumpectomies

Lumpectomy is often called breast conservation therapy because the goal is to remove as little tissue as possible to preserve the breast's normal appearance. The procedure is usually an option for women with Stage I or Stage II cancers, which are less advanced forms of the disease.

Often, women receive radiation therapy after a lumpectomy. Doctors also sometimes remove lymph nodes to check for any cancer that has spread.

Studies have shown that women who undergo lumpectomy and radiation have survival rates equal to women who have mastectomy.

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