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'Hot' new approach heats, kills liver tumors (6/16/97)

Robert Bernal was a young man of 19 when he battled a hidden enemy, the Viet Cong. "You couldn't tell who was Viet Cong and who wasn't," he remembers.

Now the 46-year-old veteran from San Antonio is battling another hidden enemy -- liver cancer. This spring doctors found he had a liver tumor 4 centimeters (a little over 2 inches) in diameter.

But Bernal recently underwent a technique called thermal ablation, a new, minimally invasive way to treat liver tumors. The procedure was performed at Audie L. Murphy Memorial Veterans Hospital in San Antonio by Gerald D. Dodd III, MD, professor of radiology at The University of Texas Health Science Center at San Antonio and staff radiologist at the VA Hospital and University Hospital.

Bernal was among the first 27 patients in a San Antonio study designed to assess whether thermal ablation will benefit patients with liver tumors. The tumors are heated--thus the term thermal--and killed. The dead tissue is slowly reabsorbed by the body.

During the procedure, a special needle is inserted into the liver tumor through a small abdominal incision, said Dr. Dodd, principal investigator on the study. The tip of the needle emits energy that heats the tumor and kills it but leaves the surrounding tissue intact. This is performed as an outpatient procedure and patients leave the hospital six hours after the treatment.

"We're investigating the use of this technique as a definitive treatment for primary or secondary liver tumors that are four-and-a-half centimeters or smaller," Dr. Dodd said. "We're one of the few research groups in the world treating patients with this procedure."

His colleagues are Glenn A. Halff, MD, associate professor of surgery at the Health Science Center and director of organ transplantation programs; Brenda Sims, PA, clinical coordinator; Hyun-Chul Rhim, MD, visiting professor from South Korea; Kedar N. Chintapalli, MD, associate professor of radiology; and Shailendra Chopra, MD, assistant professor of radiology.

Since June 1996, the researchers have treated 27 patients, including 18 with tumors that first developed in the liver (primary liver tumors), and nine with tumors that had spread to the liver from primary breast or colon cancers. Eight of the patients had multiple liver tumors.

"Of the 26 patients in whom we have attempted complete tumor ablation, 18 appear to be disease free at this time," Dr. Dodd said. "From preliminary results we've concluded that thermal ablation is a promising, minimally invasive method for treating liver tumors."

The team will present study results this summer at the annual Symposium on Cancer Research in San Antonio.

In many cases, patients receive same-day results. "We do the treatment in the morning and conduct a CT scan the same day," Dr. Dodd said. "We can tell the patient right away whether or not we killed all the tumor. Then the patients can go back to their primary care physicians for follow-up."

The only significant risk of thermal ablation is bleeding. This has occurred in one patient in the study and the risk is analogous to, or perhaps even lower than, the typical liver biopsy. "Location of the tumor in the liver can be a problem," Dr. Dodd said. "If we can't reach the tumor with our needle we can't treat it. Each case is different and requires careful evaluation." =09 Thermal ablation may be the only option for persons who aren't candidates for conventional liver cancer surgery. "Many patients can benefit," Dr. Dodd said. "Perhaps they cannot undergo general anesthesia or their tumor is in a poor location for resection. We do most ablations under conscious sedation and we have greater flexibility in treating tumors in different parts of the liver. The other advantage of this technique is that we can repeat the procedure as often as necessary to treat new sites of tumor in the liver."

Liver cancer, fairly rare in the United States, is more common in men than women. About 18,500 new cases are diagnosed each year, according to the National Cancer Institute. Patient prognosis is very poor--untreated patients usually die in three to four months and treated patients in six to 18 months. New treatments, such as liver tumor ablation, are urgently needed.

"This technique is at the cutting edge of minimally invasive therapy," Dr. Dodd said. "Only about 350 liver tumor ablations have been done worldwide. One center in Italy has treated about 200 patients and published follow-up results on about 60. That team's results show only about a 5 percent frequency of local recurrence."

The device used in the San Antonio study is approved by the U.S. Food & Drug Administration for tissue ablation. It is manufactured and marketed by RITA Medical Systems in Mountain View, Calif. The ablation device is a long, slender needle that looks like an umbrella with four prongs. The prongs are antennae that transmit radio frequency energy, heating the adjacent tissue to 100 degrees Celsius (212 degrees Fahrenheit).

The needle is inserted through the skin and directly into the liver tumor. "We keep it in the tumor for six minutes, and it forms a sphere of heat," Dr. Dodd said. "This heat is very rapidly dissipated--only millimeters from the prongs--so that the only tissue destroyed is the tumor. Basically the tumor is cooked--at a much lower frequency than a microwave oven but it works on the same principle."

Robert Bernal's procedure was performed May 21. He had suffered through a year of unrelated problems, including fluid build-up in his abdominal cavity. "I came in to have the fluid in my belly treated," he said. ''I didn't know I had a tumor, but the doctor gave me a test and the results came in positive.

"At least we are getting the tumor early," he added, ''and I know I'm in good hands at the VA Hospital and with Dr. Dodd."

Bernal is one of the first liver cancer patients to benefit from thermal ablation, but as the study results come in, it's apparent he won't be the last.

Contact: Will Sansom (210) 567-2570