RF tumor ablation breaks through in clinical practice
RF tumor ablation breaks through in clinical practice
At 7 a.m., a patient with a small, inoperable liver tumor arrives at a community hospital for a previously scheduled radio-frequency ablation. At 8 a.m., he lies in a CT scanner, sedated but conscious. A few minutes later, the interventional radiologist, guided by CT fluoroscopy, inserts a needle into the patient's abdomen. A probe slides through it and opens up, umbrella-like, within the target lesion. Because the patient seems tense, the physician tries some humor, asking before he turns on the electrode, "Medium rare or well done?"
The patient is sent to the recovery room at 9:30. He is at home by noon, and he may be playing golf a day later.
Although RFA has expanded its scope to include primary and metastatic tumors of the kidneys, bones, lungs, breast, and head and neck, it is most commonly used for treatment of unresectable tumors in the liver. In a study presented at the December RSNA meeting, Italian researchers suggested that RFA should in fact be offered as first-line treatment for patients with liver tumors.
"This is a conclusion after 16 years of percutaneous ablation of hepatocellular carcinomas in cirrhotic patients," said Dr. Riccardo Lencioni, an interventional radiologist at the University of Pisa.
Lencioni's prospective study assessed long-term survival rates of 187 cirrhotic patients with hepatocellular carcinoma treated only with RFA. Five-year survival rates were found to be similar-and in some cases superior-to those for surgery. The study included 240 liver carcinomas 5 cm and smaller, treated with ultrasound-guided RFA with 50- or 150-watt generators using expandable multiprobe needles. A subgroup of 116 patients with stable liver function and solitary lesions achieved three- and five-year survival rates of 89% and 61%, respectively.
Some 40,000 to 50,000 RFA procedures worldwide have been performed to date, according to Michael Dominici, director of marketing for Rita Medical Systems. Many researchers and radiologists believe that the rapid acceptance of RFA confirms both the clinical need for therapeutic choices and the scant treatment alternatives for patients with unresectable tumors or compromised conditions.
Surgical resection is still regarded as the standard of care for solid tumors, but in a number of patients, those tumors can pose particular challenges for surgeons. They may not, however, be as challenging for interventional radiologists, said Dr. Stephen Solomon, an assistant professor of radiology at Johns Hopkins University.
Patients who have already undergone surgery, for instance, may make good RFA candidates. Some surgeons choose not to perform surgery on patients whose postsurgery scarring makes further intervention too difficult, but this is not a limitation for RFA, which could be performed repeatedly in the future, Solomon said. RFA may also be an option for patients who refuse to undergo open surgery. In these cases, radiologists usually consult with surgeons, oncologists, and radiation therapists to develop a treatment plan.
RFA is not for everyone, however. Although results vary among institutions, the odds favor patients with no more than two or three lesions, generally smaller than 4 cm each. Because larger tumors may be harder to destroy, physicians should be realistic about what they can treat with RFA, according to Solomon.
"Your results get worse as the lesion gets bigger. I'm not saying it's wrong to go after a 4-cm lesion, but the likelihood of success on a 4-cm lesion is less than on a 2-cm lesion," he said.
Specialists such as oncologists or surgeons refer most patients who undergo RFA. Both academic and community hospitals across the country have well-defined guidelines in place for management of oncology patients, and some hospitals hold a multidisciplinary tumor consultation before clearing a patient for RFA. Other centers favor a more informal, collegial approach.
"People here are pretty open to listening outside their own specialty," said Dr. Daniel B. Brown, an assistant professor of radiology and surgery at the Mallinckrodt Institute of Radiology in St. Louis. "If I tell them I think a patient is good for RFA, they are generally happy to let me do it. We have a pretty trusting relationship."
FROM ACADEMIA TO COMMUNITY
In contrast with other interventional technologies, some of which spent years in academic "incubators," RFA has quickly caught on in clinical practice at community hospitals and private radiology clinics. In some cases, the difference in performance between teaching and community-based hospitals is not only thin but blurry.
"The distinction between community versus academic hospital, in the case of RFA, may be artificial," said Dr. S. Nahum Goldberg, director of the tumor ablation program at Beth Israel Deaconess Medical Center in Boston.
While results are highly physician-dependent, the equipment is inexpensive and simple to operate, so any hospital or radiology group willing to put together the appropriate team and invest in the necessary resources can achieve good results, Goldberg said.
The FDA's favorable regulations regarding RFA procedures and equipment have further encouraged the technique's proliferation. Of a number of RFA systems currently available, at least three-Rita Medical Systems, Boston Scientific, and Radionics-have already obtained FDA 510(k) clearance for nonresectable liver tumor and soft-tissue ablation. RF generator prices average $20,000, while the disposable probes are priced from $500 to $1400.
The two largest and best regarded RFA programs are based in community centers in Italy, an RFA bastion and long-time partner for many U.S. researchers. And some U.S. community hospitals may not be far behind their academic counterparts, Goldberg said.
Practitioners-usually radiologists, but increasingly surgeons-who perform RFA in private clinics and small hospitals are usually well acquainted with the latest methods and techniques. Many have been trained by radiologists at academic centers. The success of RFA ultimately depends not on where is performed but on patient selection, practitioner skill, and good follow-up, according to Goldberg.
While most interventionalists do not need to advertise RFA's benefits, media attention can help. A three-minute piece on RFA on the local TV channel usually gets the word out about the procedure, said Dr. Damian Dupuy, a radiologist at Rhode Island Hospital in Providence. Once patients hear about it, they often ask their physicians for more information and then spread the word to others. Patients also frequently learn about RFA on the Internet, and what they discover there may prompt a visit to an interventional radiologist.
Several CPT codes already exist for RFA of liver tumors, including CPT 47380, which could be used for open ablation of one or more liver tumors, and CPT 47382 for percutaneous ablation. A code for bone RFA is likely to be introduced next year, according to Michael Mabry, assistant executive director for policy at the Society of Interventional Radiology.
And the lack of a code for kidney, lung, and breast RFA does not mean physicians performing these procedures will not be reimbursed, he said. Radiologists can appeal when insurers challenge a procedure's medical necessity, but a number of strategies can help them avoid the hassle. These include the use of unlisted codes for the same organ system and direct negotiations with the insurance carriers for clearance in advance.
Physicians can inform insurance companies that they want to perform RFA of the lungs, kidneys, or breast and ask for guidance in obtaining reimbursement. The companies may respond with recommendations, Mabry said.
"Sometimes it takes some effort to talk to the right person. You may want to find people with a clinical background in the company's policy area and present them with the clinical literature. A little upfront effort can pay dividends in the long term," he said.
Alternatives include compensating for a procedure's losses with a high volume of procedures that are reimbursed and ascertaining the probable amount of reimbursement before investing in the equipment.
"It boils down to the fact that you have to do homework early and decide whether the reimbursement is worthwhile. Then proceed accordingly," Mabry said.
Because of the relative newness of RFA and other thermal ablation procedures such as microwave and laser ablation and focal ultrasound, no prospective randomized studies have met accepted clinical standards for follow-up. The literature on hepatocellular carcinoma and colorectal metastases, for instance, considers five or more years of follow-up as the benchmark. As a result, many clinicians remain skeptical or avoid endorsing these technologies until they are validated.
Studies of successful RFA procedures in large patient populations continue to accumulate, however. RFA shows promise in almost every organ system. The impressive body of literature on RFA of primary and metastatic liver tumors has established this application as the best therapy available when surgery is not an option.
Lencioni and colleagues at the University of Pisa have published comparative results from 102 patients with small HCCs who underwent treatment with RFA and percutaneous ethanol injection (PEI). They found that local recurrence-free survival rates for RFA were superior to those for PEI (Radiology 2003;228 :235-240). The group found similarly encouraging results for lung RFA (see accompanying article).
A group of U.S. and Italian researchers, led by Dr. Tito Livraghi and Dr. Luigi Solbiati, evaluated results of a 41-center trial that included 2320 patients with focal liver tumors, with a total of 3554 lesions treated. The group assessed the type and number of complications associated with RFA and found it to be a relatively low-risk procedure for treatment of focal liver tumors (Radiology 2003;226:441-451).
Many proponents suggest that RFA will ultimately replace surgery as the gold standard for the treatment of liver tumors, although more hard evidence is needed to support that assertion. Others, however, look at RFA from a different perspective.
"RFA is not an alternative to surgery, but it can help with surgery or transplantation," said Dr. Alain T. Drooz, an interventional radiologist at Fairfax Radiology Associates in Vienna, VA.
The procedure should be thought of as a complementary technique, Drooz said, as most patients, particularly those with primary liver cancer, are treated with a combination of therapies. In about one-quarter of patients with liver cancer, the cancer grows too large while they are awaiting a transplant. RFA can shrink these tumors and keep a patient on the transplant list.
And RFA has advantages over surgery: It usually does not require general anesthesia, is well tolerated, and can be performed on an outpatient basis. It can be repeated if necessary and may be combined with other treatment options.
Researchers and private-practice radiologists are trying out new approaches to enhance their RFA results. Some advocate embolization before ablation to obtain a larger tumor destruction zone. Others, like Goldberg, are exploring additional adjuvant techniques, including treating diseased tissues with sodium chloride solutions to increase the passage of energy, administering liposomal doxorubicin within 24 hours of RFA, and performing RFA in conjunction with chemoembolization.
Lencioni and other researchers favor temperature monitoring and the use of new probe designs. The Rita StarBust XL, for instance, is a nine-hook needle that can create an ablation sphere of up to 7 cm and is used mostly for liver and lung lesions. A new side-hole thin needle is used for ablation of osteoid osteomas.
The future also holds promise for more sophisticated image guidance and monitoring. While most interventionalists prefer CT and ultrasound, MR-compatible ablation equipment could make MR more ubiquitous. In addition, researchers see a larger role for MR in thermal mapping and monitoring of RFA. PET's role for follow-up after ablation and the use of robots to help perform RFA are two other areas of research.
Some proponents believe that a paradigm shift in radiology will make the difference between advancing these and other minimally invasive techniques within the specialty or losing them altogether. According to Dr. Theodore Phillips Chambers, a member of the SIR practice affairs committee, radiologists cannot simply wait in their interventional suites for cases.
"We have to engage ourselves in managing problems to the best of our ability, and not hide in the radiology suites, and not accept the contention from competing specialties that we don't know anything abut patient care. We have to extend our work well beyond what happens in the interventional suite," Chambers said.