Novel Treatment Approaches Radiofrequency Ablation

Radiofrequency ablation (RFA) is a relatively new technique that is rapidly gaining wide acceptance for local ablation of tumors not amenable to resection. RFA is performed percutaneously as an interventional radio-logic procedure or intraoperatively laparoscopically or as part of a laparot-omy. An RFA needle is placed within the tumor under CT or ultrasound guidance. The needle array is deployed, and thermal energy is generated. The cell membranes are destroyed, and the intracellular proteins degenerate as the temperature exceeds 45° to 50° (Figure 11-4).

Curley et al (1999) reported on 123 patients with primary or metastatic hepatic malignancies treated with RFA. Half (61) of these patients had hepatic colorectal metastases. Patients with small (<3 cm) peripheral tumors were treated with percutaneous ultrasound-guided RFA (n = 31), while the remaining patients were treated during an open operative procedure. To prevent bile duct injuries, patients with tumors near the main right or left bile ducts were excluded. Patients were still considered for RFA when the tumor abutted a major hepatic branch or the vena cava. In this series, there were no treatment-related deaths, and the complication rate was 2.4%. After a median follow-up of 15 months, only 1.8% of tumors had recurred at the RFA site. Unfortunately, 27.6% of patients had recurrence at distant sites. Two of the 3 local recurrences occurred in patients with tumors less than 6 cm in diameter. The only complications in this series were 1 perihepatic abscess and 1 hemorrhage into the treated tumor.

Solbiati et al (1997) reported on 29 patients with 44 liver metastases, most from colorectal cancer, who were treated with percutaneous RFA. At a median follow-up of 18 months, the disease-free survival rate was 33% and the overall survival rate was 89%. Progression of disease at the RFA site was seen in 34% of treated lesions. This is in contrast to the 1.8% local recurrence rate reported by Curley et al (1999). All patients in Solbiati et al's study were treated percutaneously, whereas only 25% of the patients in the series of Curley et al were treated in this manner. Curley et al used the percutaneous technique only in isolated peripheral lesions, while

Figure 11-4. Radiofrequency ablation (RFA) of a liver metastasis. Computed tomography scans of liver metastases before (A) and 3 months after (B) RFA. Reprinted with permission from Curley et al (1999).

Solbiati et al used the percutaneous technique in patients with multiple central lesions. This difference in approach may directly affect the ability to achieve complete tumor destruction.

It appears from preliminary data that RFA can be used as a local ablative technique when the patient is not a candidate for surgery. Unfortunately, the extrahepatic recurrence rate is high because patients remain at risk for systemic failure. RFA should further be investigated as part of prospective studies because current studies provide only short-term follow-up data. At M. D. Anderson, RFA is now being used alone or in combination with resection in patients in whom resection is contraindi-cated or in whom a complete resection is not possible.

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