Awareness of complications improves survival rates

Efficient planning that considers variables and prognostic factors proves vital in RF tumor ablation A group of radiologists from Seoul learned some important lessons from more than 3000 radiofrequency ablation procedures carried out in patients with hepatic tumors during the past decade.

"Good planning is most important for successful treatment, as in any kind of therapy," said Dr. Hyunchul Rhim, a radiologist from Samsung Medical Center (SMC) at Sunkyunkwan University Hospital. "In the planning phase, we need to decide whether RF ablation can be successfully performed."

RFA has become accepted as a safe and effective technique for unresectable hepatic tumors. The SMC team has published its clinical findings in more than 30 peer-reviewed journal articles. Their one-, three-, and five-year survival rates in 570 patients with hepatocellular carcinoma were 95%, 70%, and 58%, respectively, and the rate of major complications was 1.9%. The five-year survival rate for 37 patients with single hepatic metastases from colorectal cancer was 48.5%.

About 87% of the procedures were performed percutaneously under ultrasound guidance and local/conscious sedation on an inpatient basis. Internally cooled electrodes were used in more than 90% of the procedures. All single tumors were less than 5 cm in diameter, and multiple tumors were less than 3 cm. Follow-up involved a contrast-enhanced liver CT scan one month postablation and CT scans every three months thereafter.

"We should remember that RF ablation is one of the multimodality treatments," Rhim told delegates at the most recent Radiological Society of North America meeting. "The final purpose of any treatment is to improve the patient's survival rather than complete ablation on an imaging study. Therefore, we should not insist on treating by RFA, and we need to consider any alternatives if there is a possibility of dangerous or incomplete ablation. If it is feasible, we need to determine the proper approach, guiding modality, type of electrode, and overlapping ablations." Safe ablation is the secret to successful ablation, and interventional radiologists must understand the broad spectrum of complications that can be encountered after RFA, according to the SMC team. The most common complications that result in mortality are bleeding, massive infarction, extensive abscess with sepsis, and thermal injury of the colon. Operators must consider any technical tips for minimizing complications. During the ablation, it is more important to monitor the patient closely than the RFA zone. After the ablation, close monitoring of the patient is mandatory to detect any complications early and manage them appropriately.

The total number of complications at the SMC was 35, amounting to about a 6% rate. The number of major complications was 11, and the mortality rate was 0.1%, or three per 3000 sessions. Complications after percutaneous RFA for hepatocellular carcinoma include biloma, intraperitoneal hemorrhage, abscess, hepatic infarction, cancer seeding, pneumothorax, hemothorax, and acute cholecystitis.

To maximize safety, Rhim recommends not treating high-risk patients, becoming familiar with the range of complications after RFA, planning carefully to minimize complications, applying all technical means to avoid complications, and pursuing early detection and proper management of complications.

Using the proper electrode, and ensuring it is kept at a safe distance from the patient's abutting organ, is also vital. To minimize thermal injury to the abutting organ, the SMC group induces artificial ascites via a 6-French angio sheath introducer. They use 300 to 700 mL of 5% dextrose-in-water (D/W) solution. The technical success for artificial ascites is 93%.

The ablative margin surrounding the index tumor is the most important prognostic factor related to complete treatment, Rhim said. To achieve an ablative margin of at least 5 mm, it is necessary to take account of the configuration of the tumor, the RF ablation zone made by a specific electrode, and the direction of the RF electrode path. The sizes and configurations of the RF ablation zone are variable, depending on a specific device.

"For complete ablation, do not treat the patient with too large a tumor," said Rhim. "Also, consider the heat-sync effect and remember the ablative margin is the key factor for local tumor control."

-By Philip Ward