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From the Divisions of Surgical Oncology, John Wayne Cancer Institute, Santa Monica, California; and Century City Cancer Center, Los Angeles, California.
Correspondence: Address correspondence to: Anton J. Bilchik, MD, John Wayne Cancer Institute, 2200 Santa Monica Blvd., Santa Monica, CA 90404; Fax: 310-449-5261; E-mail: bilchika{at}jwci.org
Hepatic malignancies are extremely common in the United States and often present a therapeutic dilemma. Surgical resection is considered to be the only curative treatment modality, with 5-year survival rates between 20% and 35%.1–3 Many hepatic malignancies, however, are unresectable at presentation, indicating a dismal prognosis.4,5 The success of local therapy in the form of resection has been the impetus for developing ablative techniques to destroy unresectable liver tumors.
Radiofrequency ablation (RFA) is a local therapy that uses relatively inexpensive instrumentation. It can be performed in the operating room via celiotomy or laparoscopy or in the radiology suite via a percutaneous approach. Radiofrequency current used to coagulate tissue was first described by Clark in 1911 and was subsequently popularized in surgery by the work of Cushing and Bovie (a physicist).6 The application of high-frequency alternating current within tissue led to the development of monopolar and bipolar tissue ablation devices. Application of alternating electric current directly to a tumor causes ion agitation that results in localized frictional heating and, ultimately, coagulative necrosis.
Numerous safety and efficacy studies led to US Food and Drug Administration (FDA) approval of RFA for the treatment of hepatic malignancies. The enthusiastic response among interventional radiologists and surgeons is reflected in recent literature: since 2001, more than 560 citations and 215 publications on RFA have appeared. In 2002, current procedural terminology (CPT) codes were introduced for open RFA (47,380), laparoscopic RFA (47,370), and percutaneous RFA (47,382).
Despite the rapidly increasing use of RFA, a systematic review on the outcomes of RFA for unresectable hepatic metastases reveals a dearth of long-term or even intermediate follow-up data. Seidenfeld et al.7 found only seven articles that provided data on disease-free or recurrence-free survival, rates of hepatic relapse, and median or percent survival at 1 to 5 years after treatment. All studies used percutaneous RFA with visualization by transabdominal ultrasonography. Five studies reported 86% to 94% survival at 1 year, but only one study reported survival at 2 years or longer.8,9 Of the lesions that appeared completely ablated on images generated by computed tomography, 12% recurred at 6.5 months and 25% at 12 months or more. The authors could find no studies that reported median survival and only one study that reported survival at 2 or 3 years. They also could find no outcome data for the use of RFA in combination with other therapies. This is in marked contrast to hepatic resection, for which a large body of data demonstrates 25% to 40% rates of 5-year survival and the only proven potential for cure.1,10–12
In this edition of Annals of Surgical Oncology, Dr. Pawlik and his colleagues13 evaluate 172 patients who had hepatic resection and simultaneous RFA. Their study included all patients who had histologically confirmed primary or metastatic hepatic malignancy with no evidence of extrahepatic disease. Unlike the Seidenfeld et al.7 analysis, all patients had laparotomy and intraoperative ultrasonography. A total of 387 tumors were resected and 350 tumors were ablated. The median number of tumors per patient was three, the median number of resected tumors per patient was two, and the median number of ablated tumors was one. At a median follow-up of 21.3 months, the rate of recurrence was 56.9% (98 patients). Failure at the RFA site occurred in only 2.3% of lesions, and the median survival time was 45.5 months. Noncolorectal metastasis, operative blood loss, and large (>3 cm) size of ablated tumor decreased survival, but lesion size was the only factor that remained significant in multivariate analysis. The overall mortality rate was 2.3% and the complication rate was 19.8%. Most complications, however, were minor and not necessarily related to the type of procedure performed.
These results provide a compelling argument for aggressive cytoreduction if patients are carefully selected and the procedure is performed at a center of excellence. The extraordinary results, however, are tempered by the fact that this is a retrospective study and little information is given on the chemotherapy regimens, which may also have had an impact on survival. In addition, the data presented here either do not correlate with or are contradictory to those supported by larger and longer studies of hepatic resection for colorectal metastases. The lack of influence of lesion size or number of treated lesions (up to 10), and the relatively good prognosis associated with synchronous disease are curious in this regard. Additional studies are needed to determine if these findings reflect study power or patient selection, or if they are the result of some phenomenon associated with ablation itself. The ability to perform RFA, however, clearly increased the number of patients whose hepatic disease was addressed in the operating room and decreased the risk of liver failure because of insufficient hepatic reserve.
If hepatic lesions can be ablated with such a high rate of success and if ablation can be performed percutaneously, why is surgery needed at all? Percutaneous RFA, unquestionably the least invasive technique, can be performed on an outpatient basis. Preprocedural imaging is not, however, sensitive for the detection of peritoneal disease and is not as sensitive as intraoperative ultrasonography for the detection of small hepatic tumors. Intraoperative ultrasonography and laparoscopy comprise the most accurate method for the detection of small hepatic lesions and peritoneal implants.14,15 Approximately 12% of patients having laparoscopy before RFA may have extrahepatic disease and, therefore, are not candidates for potentially curative procedures.16 Rahusen et al.15 showed that diagnostic laparoscopy and ultrasonography upstaged more than one third of patients with hepatic tumors: 38% of cases were deemed unresectable, despite thorough preoperative imaging. John et al.17 reported a significantly higher rate of resection for cancers staged by laparoscopy and laparoscopic intraoperative ultrasonography (93%) than by laparotomy (58%). Similarly, Clarke et al.18 showed that 40% of the lesions demonstrated by laparoscopic intraoperative ultrasonography were neither visible nor palpable at surgery. At our institution, combined laparoscopy and laparoscopic intraoperative ultrasonography changed the operative management in 32% of the patients. Laparoscopy detected more lesions in 11 of 50 patients, and laparoscopic ultrasonography detected more lesions in 18 of 50 patients.19
Radiofrequency ablation is safe and effective for local ablation of hepatic malignancies. This highly versatile technique can be applied laparoscopically, percutaneously, or at open celiotomy, as a primary treatment or in conjunction with resection. Operative approaches allow more accurate assessment for the presence of extrahepatic disease, better evaluation of intrahepatic disease, and isolation of the liver from adjacent organs that may be injured. Percutaneous RFA should be reserved for patients who are not operative candidates and patients with recurrent disease. Patients with hepatic recurrences can be managed chronically with percutaneous RFA, with no cumulative toxicity. Because of the high rate of disease progression at intrahepatic and extrahepatic sites, hepatic and systemic chemotherapy should be considered after RFA. Review of these cases in a multidisciplinary setting is crucial to determine the potential for resection and the optimal route of administration if RFA is selected. Current data do not support the use of RFA in lieu of hepatic resection.
Received for publication September 9, 2003. Accepted for publication September 23, 2003.
REFERENCES
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