Percutaneous Radiofrequency Ablation of Liver Tumors

Updated: Nov 07, 2017
  • Author: Badar Bin Bilal Shafi, MBBS, MRCP, FRCR, CCT, EBIR; Chief Editor: Kurt E Roberts, MD  more...
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Overview

Background

Percutaneous radiofrequency (RF) ablation (RFA) is an exciting approach to destroying inoperable primary tumors or metastases in the liver. [1, 2] In the treatment of hepatocellular carcinoma (HCC), fewer than 40% of patients are candidates for surgery, and the rate of recurrence after curative surgery is high. Percutaneous techniques like RFA are, therefore, very important. RFA is widely used for metastatic and small primary tumors. [3] It serves as a bridge for transplant candidates, especially in relation to small primary lesions. [4]

Percutaneous RFA is a minimally invasive, repeatable procedure with few complications. It is performed under radiologic guidance. Randomized controlled trials showed that RFA is superior to ethanol injection in the treatment of small HCCs. [5] RFA results in a higher rate of complete necrosis and requires fewer treatment sessions than percutaneous ethanol injection (PEI). [6, 7, 8]

Long-term survival rates are also better with RFA. A randomized clinical trial showed that RFA yields a significantly better 1-year complete response rate than does PEI. [5] RFA in combination with transcatheter arterial chemoembolization (TACE) is also an effective treatment for inoperable hepatic tumors. [9]  RFA combined with TACE also appears to be safe and effective in the treatment of breast cancer with liver metastasis. [10]

Studies comparing percutaneous RFA and percutaneous microwave coagulation therapy (PMCT) showed better results with RFA in treatment of small tumors. RFA results in better survival rates, fewer complications, and significantly lower local recurrence rates. [11, 12]

In RFA, a needle is inserted into the liver, usually under the guidance of ultrasonography or computed tomography (CT). Once the needle is placed within the tumor, a generator is used to deliver a rapidly alternating current (RF energy). This needle may be bipolar or unipolar; the latter requires grounding pads placed on the patient's thighs. Heat is generated at the site of the lesion through frictional heat produced by rapid agitation of adjacent cells and produces destruction (liquefactive necrosis) of the tumor.

This technology is used widely in Europe and the United States. Shiina et al noted that by 2007, at least 1500 institutes in Japan had introduced RFA in the treatment of liver tumors. [13]

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Indications

In the treatment of HCC, the range of indications for percutaneous RFA is becoming wider than that of surgery and intra-arterial therapies, and it includes the following main categories [5, 1] :

  • HCC at an early stage [14, 15]
  • Primary treatment for small tumors [16, 17]  - A meta-analysis by Jansen et al described local ablative techniques as the treatment of choice for small HCC [18] ; the National Institute for Clinical Excellence (NICE) in the United Kingdom also recommended RFA as the treatment of choice in small tumors [19]
  • Inoperable primary liver tumor
  • Treatment of patients who cannot undergo general anesthesia or are not operative candidates because of comorbidity or advanced age
  • Liver metastasis, most commonly colorectal, especially if the patient is not an operative candidate [20]
  • Can be used for breast, [21] thyroid, [22] and neuroendocrine metastasis [23]
  • Treatment of patients who have a hepatoma or multiple small lesions and are waiting for liver transplantation [4]
  • Recurrent and progressive lesions [24]  - RFA has been used in conjunction with PEI as an alternative to repeat hepatectomy in elderly patients with recurrent HCC after initial hepatic surgery [25]
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Contraindications

Contraindications for percutaneous RFA of liver tumors include the following:

  • Bile duct or major vessel invasion
  • Significant extrahepatic disease
  • Child class C cirrhosis or active infection
  • Decompensated liver disease
  • Lesions that are difficult to reach with electrodes or when electrode placement is impaired - In such cases, an open rather than percutaneous approach should be used [26] ; it should be noted, however, that RFA of liver tumors located in the caudate lobe is effective despite this segment's deep location and the proximity of the vessels [27, 28]
  • Tumors that occupy more than 40% of the volume of the liver - Tumors of this size cannot be safely ablated, because the liver reserve left after RFA might not be sufficient to preserve hepatic function
  • Proximity to vital structures like vessels and adjacent organs [29] - This is a relative contraindication; open RFA is suggested by one study [26]
  • Lesions larger than 5 cm (relative contraindication) - RFA should be used cautiously for lesions larger than 5 cm; one study suggests the use of open RFA for lesions larger than 5 cm [26]
  • Patients with metastatic lesions larger than 3 cm - These lesions are not optimally suited for RFA, because the risk of recurrence is high [20]
  • Large or numerous tumors - Multiple studies recommend RFA as a choice if there are fewer than three tumors, each of them measuring less than 3 cm [30, 31, 32]
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Outcomes

One randomized controlled trial showed that the 2-year recurrence rate of HCC was significantly lower with RFA than with percutaneous ethanol injection (PEI). When compared with surgical resection, the recurrence rate is higher after RFA, with less time to recurrence. [33]  Recurrence is more common with the percutaneous approach as compared with open or laparoscopic RFA. The rate of recurrence is also higher with lesions larger than 3 cm. [34]

In a study by Toshimori et al, the local recurrence rates after percutaneous RFA for HCC were 2.2% at 1 year, 7.4% at 3 years, and 9.5% at 5 years. [35] Factors that predisposed to local recurrence included large tumor size (>2 cm), tumor location adjacent to the major portal branch or hepatic vein), and a small (<3 mm) ablated margin.

Shady et al assessed factors affecting outcome in patients with colorectal cancer liver metastases who were treated with percutaneous RFA. [36] On multivariate analysis, factors predictive of shorter local tumor progression-free survival were a tumor size exceeding 3 cm and a margin size of 5 mm or less; factors predictive of shorter overall survival were a tumor size exceeding 3 cm and the the presence of more than one site of extra-hepatic disease.

Yamao et al compared the survival impacts of RFA (n = 33) and hepatic resection (n = 71) as initial treatment of HCC in 104 patients with liver damage B as defined by the Liver Cancer Study Group of Japan. [37] Whereas overall survival (OS) tended to be better in the RFA group, disease-free survival (DFS) did not differ significantly between groups. Subgroup analyses found OS with RFA to be significantly better in patients with aspartate aminotransferase above 35 IU/L, serum albumin below 3.5 g/dL, and 99mTc-galactosyl human serum albumin below 0.85.

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