Radiofrequency ablation of unresectable primary and metastatic hepatic malignancies: results in 123 patients

Abstract

Objective: To describe the safety and efficacy of radiofrequency ablation (RFA) to treat unresectable malignant hepatic tumors in 123 patients.

Background: The majority of patients with primary or metastatic malignancies confined to the liver are not candidates for resection because of tumor size, location, or multifocality or inadequate functional hepatic reserve. Local application of heat is tumoricidal; therefore, the authors investigated a novel RFA system to treat patients with unresectable hepatic cancer.

Patients and methods: Patients with hepatic malignancies were entered into a prospective, nonrandomized trial. The liver tumors were treated percutaneously or during surgery under ultrasound guidance using a novel LeVeen monopolar array needle electrode and an RF 2000 generator. All patients were followed to assess complications, treatment response, and recurrence of malignant disease.

Results: RFA was used to treat 169 tumors (median diameter 3.4 cm, range 0.5 to 12 cm) in 123 patients. Primary liver cancer was treated in 48 patients (39.1%), and metastatic liver tumors were treated in 75 patients (60.9%). Percutaneous and intraoperative RFA was performed in 31 patients (35.2%) and 92 patients (74.8%), respectively. There were no treatment-related deaths, and the complication rate after RFA was 2.4%. All treated tumors were completely necrotic on imaging studies after completion of RFA treatments. With a median follow-up of 15 months, tumor has recurred in 3 of 169 treated lesions (1.8%), but metastatic disease has developed at other sites in 34 patients (27.6%).

Conclusions: RFA is a safe, well-tolerated, and effective treatment to achieve tumor destruction in patients with unresectable hepatic malignancies. Because patients are at risk for the development of new metastatic disease after RFA, multimodality treatment approaches that include RFA should be investigated.

Figure 1. LeVeen needle electrodes showing the multiple array retracted into the needle sheath (left) and fully deployed (right) from the needle tip. The ten individual tines of the multiple array are clearly seen with the array deployed to the full 3.5-cm diameter.

Figure 2. A graphic display of power (in watts) and tissue impedance (in ohms) during RFA of a malignant liver tumor. Using ultrasound guidance, the LeVeen needle electrode is placed into the tumor and the multiple array is deployed. Treatment is then initiated at 50 W of power and increased by 10 W at 1-minute intervals up to a maximum power of 90 W. At 8 minutes, RFA-induced coagulative necrosis of the tumor is occurring; the tissue impedance at this point rapidly rises to more than 200 ohms and the power output precipitously falls (roll-off). After waiting 20 seconds to allow heat in the tumor to dissipate, RF energy is again applied at approximately 75% (70 W) of the maximum power achieved, until tissue impedance again rises and power rolls off. This two-phase application of RF energy is performed in each area treated with the LeVeen multiple array needle electrode.

Figure 3. (A) Pretreatment CT scan in a patient with two colorectal cancer liver metastases (arrows). (B) CT scan 6 months after resection of the left lobe tumor and RFA of the right lobe tumor. The RFA lesion (open arrow) is larger than the original treated tumor; RFA treatment is planned in each tumor to coagulate the tumor and an approximately 1.0-cm rim of surrounding hepatic parenchyma. The intrahepatic cystic area at the site of RFA remains unchanged or involutes slightly on CT or MRI scans performed as long as 2 years after treatment.

Figure 4. (A) Pretreatment CT scan in a patient with two large liver metastases (arrows) from colorectal cancer. (B) CT scan 1 month after resection of the left lobe lesion and RFA of the right lobe tumor that measured 11.0 × 8.0 × 6.5 cm. There is complete necrosis of the large right lobe lesion (open arrows) that was treated with multiple intraoperative applications of RF energy to all areas of the tumor.

Figure 5. (A) Pretreatment CT scan in a patient with HCC near the inferior vena cava (open arrow) and the right and middle hepatic veins (solid arrows). (B) CT scan 3 months after intraoperative RFA of the liver tumor. Again, the RFA lesion is larger than the original treated tumor. Complete necrosis of tumor is noted, but the right and middle hepatic veins (solid arrows) are patent.