Radiofrequency ablation technique burns away difficult-to-reach liver tumors

By SEAN GRIFFING

Liver cancer is notoriously tricky to diagnose. Doctors can't feel tumors during a checkup because the liver is hidden under the ribs, and patients seldom feel pain until a rapidly growing tumor has become quite large.

With a late diagnosis, patients live only about six months; worldwide, liver cancer kills half a million a year. To compound matters, surgery isn't always an option because many patients aren't healthy enough. Or, surgery won't work because the tumor has spread throughout the liver or is located in a critical area.

Mahmood Razavi, MD, associate professor of interventional radiology, has provided relief for these patients with an unusual procedure that literally burns tumors away. Called liver cancer radiofrequency ablation, the technique has allowed some patients to live five times longer than they would otherwise.

Radiofrequency energy burns away a liver tumor, then exits the body via pads placed on the legs.

"After surgery, you get knocked out for a week or two." Razavi said. "But with ablation, patients frequently go home the same day and can resume their normal activities the next day." Razavi points out that the procedure is neither a cure-all nor are all patients appropriate for ablation, "But a good percentage are."

Razavi's team uses an ultrasound or CAT scan to map the location of the tumor. With the image as a guide, a needle is inserted with pinpoint accuracy into the center of the tumor. When he's ready to start burning the tumor, he sends radiofrequency energy through a wire and into the needle.

At the needle's tip, electrons start dancing, building up friction. This action heats nearby tissue to about 150 F, burning away the tumor. Meanwhile, the hyperactive electrons escape the body through two pads placed on the patient's upper legs. The pads lead back to the needle's power source, with the body functioning like a wire, carrying the energy. The procedure takes an hour or two, depending on the number of tumors.

"Liver cancer ablation is a relatively new technique," Razavi said. "Experimental work has been going on for the past few years. But it has really gotten into clinical applications at selective medical centers in the past three or four years."

Razavi along with other colleagues inlcuding Samuel So, MD, associate professor of surgery, organized the first hands-on workshop in the United States to teach the procedure to other physicians. These days, So relies on the ablation procedure during more traditional surgery when he encounters a difficult-to-remove tumor.

For surgery patients, the quarter-inch incision needed for ablation is much less invasive than open surgery, but Razavi believes the more traditional approach should be considered first "since it is the gold-standard for now." Not all oncologists are convinced of the new procedure's benefits, said Razavi. Despite accurate image guidance, problems can occur, such as injury to other organs around the tumor.

Surgery still gives a doctor more assurance that all the cancer has been removed, explained So. Not all liver cancer tumors can be completely destroyed by ablation, he added. Tumors located near major blood vessels may not be eradicated, for instance, because surrounding blood flow keeps them relatively cool.

Kidney and lung cancers can be treated with ablation as well. It can also be used to shrink troublesome tumors instead of removing them, Razavi said, though in liver cancer, "we go for the kill; we try to destroy the entire tumor."

Sidebar:

In modern cancer treatment, imaging is everything

Liver cancer ablation is just one type of image-guided tumor therapy available at the medical center. Every year about 200 cancer patients are treated at Stanford with the help of these high-tech tumor-finding techniques. "It's an exciting area in cancer treatment. Image-guided therapy is going to be the fourth arm of treatment against cancer after surgery, chemotherapy and radiation" Razavi predicted.

Each year, Stanford plays host to some 40 visiting doctors learning to perform image-guided therapy. There's even a two-year waiting list for the opportunity.

Many visiting doctors become interested in Stanford's unique liver tumor board that was started in 1998, said Razavi. On Tuesdays at 10 a.m., a team of liver surgeons, oncologists, interventional radiologists and other specialists discuss each liver cancer patient and decide on the best treatment options.

"Physicians come here to train for image-guided cancer therapies. But everybody wants to learn about the liver cancer board so they can take it back to their hospitals and institute the same approach to patient care for their liver cancer patients," Razavi said.