Liver Tumors Can't Take the Heat

 

Dr. Steven A. Curley explains a new procedure known as radiofrequency ablation for the treatment of liver tumors to patient Marcos Bertoldi.

 

 

A technique that destroys tumors with a heat probe is helping turn the tide for some liver cancer patients at M. D. Anderson.

 

Called radiofrequency ablation, the new treatment offers hope for prolonged survival for selected patients with primary liver tumors and also for patients whose cancers have spread from other organs to the liver. In the former group, the heat probe may be used for tumors that are considered unresectable as well as for patients who undergo liver surgery.

 

Candidates in the second group should not have metastatic disease outside the liver.

 

"After evaluating radiofrequency ablation in more than 80 patients, I am optimistic that this method will extend our treatment options for more patients with either primary or metastatic liver tumors," notes Dr. Steven A. Curley, associate professor of surgery and medical director of M. D. Anderson's Gastrointestinal Center.

 

Dr. Curley has been at the forefront in evaluating the technique since 1995, when he conducted pre-clinical research in pigs. This species was used because pigs' blood vessels are similar to humans. The animal studies illustrated the method was safe and effective.

 

In 1996, he went to the G. Pascale Foundation at the National Cancer Institute in Naples, Italy, to work with colleagues in applying radiofrequency ablation to patients. That collaboration was very productive, in part due to the high incidence of primary liver cancer in southern Italy. The first M. D. Anderson patients had the procedure a year later.

 

Dr. Curley was "encouraged by early results" from two pilot studies, which showed:

 

· Radiofrequency ablation can treat liver tumors as large as a Texas grapefruit.

 

· The technique can destroy liver tumors on or near major blood vessels.

 

· Side effects are minimal.

 

· As many as six to eight tumors can be treated so long as the combined tumor volume is less than 40 percent of the total liver volume.

 

Radiofrequency ablation can be performed during conventional open surgery or through an instrument called a laparoscope inserted into the abdomen. Intraoperative ultrasound is used to guide the heat probe to the liver tumors.

 

The slender, foot-long probe contains a 16-gauge needle with a tiny device that opens like the ribs of an umbrella and through which electric current is passed. The probe is connected to a briefcase-size generator that supplies heat to 80-100 degrees Centigrade.

 

"By placing the needle electrode in the tumor, a controlled ablation can be achieved. We have been able to destroy tumors up to five inches in diameter without causing bleeding problems," Dr. Curley explains.

 

Fewer than 14,000 new cases of primary liver cancer were predicted last year in the United States. While not a common form of cancer in this country, it is listed as the 10th leading cause of cancer deaths among American men. The liver also is the second most prevalent site for cancer metastasis (after the lymph nodes).

 

Worldwide, primary liver cancer is the most common solid tumor, largely because of the high incidence of hepatitis virus infection in so many countries. Hepatitis B or C virus infection predisposes a large number of people to primary liver cancer.

 

The outlook for curing liver cancer has long been bleak. Dr. Curley cited studies showing that 80 to 90 percent of patients who develop liver tumors are unable to have surgery. Of the remaining 10 to 20 percent, only one-fourth undergo surgical resections. Thus, 95 percent of patients cannot be treated successfully.

 

That dismal prospect has prompted an aggressive approach using combination chemotherapy, surgery and newer treatment methods at M. D. Anderson, where almost 500 patients were seen for liver problems last year. Approximately 150 major liver resections were performed. Surgery is usually combined with chemotherapy, often given through implantable pumps or through innovative techniques that allow powerful anti-cancer drugs to be infused directly into the liver.

 

"Knowing we have had relatively few options to treat liver tumors has been very frustrating - but also has motivated us to find new treatment methods," Dr. Curley says.

 

He recently compared results between radiofrequency ablation and cryoablation, a technique that freezes tumors with liquid nitrogen. The question was "whether to freeze or fry" the liver tumors.

 

Dr. Curley's analysis found many more side effects attributed to cryoablation, which cannot be applied to tumors larger than 2 1/2 inches in diameter. In reviewing 54 patients who had cryoablation with 72 patients who had the heating technique, he documented 24 complications in the cryoablation group but only two minor side effects linked to radiofrequency ablation. The heat treatment costs about one-tenth that of the freezing method.

 

Two phase II clinical trials recently opened for (1) patients with inoperable primary or metastatic tumors in the liver and (2) for patients with unresectable colon and rectal cancer metastasis in the liver. Up to 60 patients will be enrolled in each study.

 

"The second clinical trial will combine chemotherapy with the heat technique, which has been approved by the U.S. Food and Drug Administration. Patients will take anti-cancer drugs delivered for six months to the liver via an intraarterial hepatic infusion pump after having radiofrequency ablation," Dr. Curley says.

 

Based on his early results with colleagues in Italy and at M. D. Anderson, an international clinical trial has commenced to assess radiofrequency ablation performed for patients in several countries. Pooling data from multiple centers should help liver cancer specialists offer more effective treatments sooner.

 

"Over time, I expect radiofrequency ablation to allow an increasing number of patients with both primary and metastatic liver tumors to be treated effectively," Dr. Curley predicts.

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