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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 45  |  Issue : 1  |  Page : 8-13

Study of therapeutic efficacy of percutaneous radiofrequency ablation versus percutaneous microwave ablation for hepatocellular carcinoma


1 Department of Internal Medicine, Faculty of Medicine, Tanta University, Tanta, Egypt
2 Department of Radiology, Faculty of Medicine, Tanta University, Tanta, Egypt

Date of Submission21-Dec-2016
Date of Acceptance16-Mar-2017
Date of Web Publication28-Jun-2017

Correspondence Address:
Mohamed A Riad
Department of Internal Medicine, Faculty of Medicine, Tanta University, Tanta, 31512
Egypt
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DOI: 10.4103/tmj.tmj_45_16

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  Abstract 


Background
In the past two decades, thermal ablation therapy using energy sources has been increasingly accepted due to the advantages of greater capacity to devitalize hepatocellular carcinoma (HCC) with fewer treatment sessions. Among them, radiofrequency ablation (RFA) and microwave ablation (MWA) are the most commonly used modalities.
Aim
The aim of study was to compare RFA versus MWA in terms of therapeutic efficacy.
Patients and methods
This study included 130 patients proved to have HCC. They were divided into two groups. Group I included 70 patients who underwent RFA. Group II included 60 patients who underwent MWA.
Results
Comparison of complete ablation (CA), partial ablation (PA), local tumor progression (LTP), and distant recurrence was made between the two groups. The CA rate was 86.6% for the RF group and 91.6% for the MW group but without significance in lesions lower to 3 cm in diameter (P=0.7981). However, this difference was significant in lesions measuring 3.1–4 cm in diameter; the CA rate was 33.3% for the RF group and 85.7% for the MW group (P=0.0388). The PA rate was 13.3% for the RF group and 8.3% for the MW group but without significance in lesions lower to 3 cm in diameter (P=0.5843). However, this difference was statistically significant in lesions measuring 3.1–4 cm in diameter; the PA rate was 66.6% for the RF group and 14.2% for the MW group (P=0.0045). During the 18-month follow-up period for tumors lower to 3 cm in diameter of both groups, the LTP rate was 21% in the RF group and 13% in the MW group with a nonsignificant difference (P=0.1944), whereas for larger tumors (3.1–4 cm in diameter) the LTP rate was 33% in the RF group and 11% in the MW group with a significant difference (P=0.0387). Tumor distant recurrence was observed in 25 (41.6%) patients of the MW group and in 30 (42.8%) patients of the RF group with a nonsignificant difference (P=1.0000).
Conclusion
MW ablation is superior to RF ablation in HCC treatment, especially large one.

Keywords: hepatocellular carcinoma, microwave ablation, radiofrequency ablation


How to cite this article:
Riad MA, Elsawy AA, Tawfik Elbadry AM, Sayed Ahmed LM. Study of therapeutic efficacy of percutaneous radiofrequency ablation versus percutaneous microwave ablation for hepatocellular carcinoma. Tanta Med J 2017;45:8-13

How to cite this URL:
Riad MA, Elsawy AA, Tawfik Elbadry AM, Sayed Ahmed LM. Study of therapeutic efficacy of percutaneous radiofrequency ablation versus percutaneous microwave ablation for hepatocellular carcinoma. Tanta Med J [serial online] 2017 [cited 2017 Oct 20];45:8-13. Available from: http://www.tdj.eg.net/text.asp?2017/45/1/8/209100




  Introduction Top


Hepatocellular carcinoma (HCC) is a malignant tumor and is the fifth most commonly occurring type of cancer. It has a high incidence rate, with ∼500 000–1 000 000 cases each year [1],[2]. HCC is also the third most lethal type of cancer [1],[2].

Hepatectomy and liver transplantation are still the essential radical treatments for HCC [3],[4]. Unfortunately, less than 30% of HCC patients are eligible for resection due to advanced tumor stage at the time of diagnosis and underlying liver cirrhosis [5].

Transplantation is indicated for underlying liver failure, and the recurrence rate is significantly lower with transplantation than with resection [6]. However, HCC recurs frequently due to its multicentric nature, which requires repeated treatments, and often results in progressively lower treatment options because of severe underlying liver dysfunction [7].

Currently, image-guided ablation therapies are the most widely used strategies for HCC due to its minimal invasiveness, repeatability, relatively low cost, easy performance, and potential application in a wider spectrum of patients [8]. They can be divided into two categories − that is, chemical ablation (mainly instillation of ethanol or acetic acid) and thermal ablation [radiofrequency (RF), microwave (MW) laser, and cryoablation) [8].

In the past two decades, thermal ablation therapy using energy sources has been increasingly accepted due to the advantages of greater capacity to devitalize HCC with fewer treatment sessions [8],[9], among which are radiofrequency ablation (RFA) and MW modalities. RFA has been used as the most popular method for treating early-stage HCC [10].

However‚ microwave ablation (MWA), which generates an electromagnetic field in the tissue and causes rapid and homogenous rotation of molecules to damage the tumor thermally [11], has been frequently used in the HCC treatment with reported efficacy and safety [12]. However, only few studies have actually compared RFA with MWA, and hence our study was designed to compare these two methods in terms of therapeutic efficacy.


  Patients and methods Top


Patients

Our prospective study was carried out at the Hepatology Unit of Internal Medicine Department at Tanat University Hospitals from September 2014 to March 2015.

Totally, 130 patients diagnosed as having HCC on the basis of typical findings of triphasic contrast-enhanced computed tomography (CT) were included. The classic imaging profile associated with HCC lesion is characterized by intense arterial enhancement or uptake, followed by contrast washout in the delayed phase [13].

All participants provided informed written consent and the study was approved by Tanta Faculty of Medicine Ethical Committee.

All patients were divided into two groups according to the type of ablation used. Group 1 included 70 patients (with 105 tumors) treated with RF ablation, and group II included 60 patients (with 95 tumors) treated with MW ablation.

The patients’ age, sex, and tumor criteria are shown in [Table 1]. The most important biochemical laboratory variables including liver functions in terms of aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin, and albumin levels were determined and compared few days before and 72 h after ablation, as shown in [Table 2].
Table 1 General characteristics of the studied groups

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Table 2 Effects of ablation procedures on laboratory variables of studied patients

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Inclusion criteria

All patients fulfilled the following criteria: child A or child B, prothrombin concentration 60% or more, platelet count 70.000/ml or more, number of focal lesions not more than three, and maximum diameter of focal lesions not more than 4 cm.

Exclusion criteria

Exclusion criteria were as follows: portal vein thrombosis, presence of lesions larger than 4 cm in diameter, lesions more than three in number in early-stage HCC, presence of focal lesions adjacent to important structures such as the diaphragm, inferior vena cava, portal vein, hepatic arteries and veins, gallbladder, common bile duct, colon or stomach and subcapsular lesions, abdominal lymph node infiltration, extrahepatic metastasis, presence of other malignant tumors, platelet count less than 70 000, prothrombin concentration less than 60%, terminal hepatic patients (child C patients), poor general condition, intolerability to general anesthesia or pain, and moderate-to-marked ascites.

Methods

All patients were subjected to the following: full history taking, complete clinical examination, routine laboratory investigations including complete blood count, prothrombin time and activity, total bilirubin, AST, ALT, albumin, urea, and creatinine, and contrast-enhanced CT scanning.

Thermal ablation procedures

RFA was performed by introducing LeVeen Needle Electrode (Boston Scientific Corporation, Natick, Massachusetts, USA) Radiotherapeutics through skin under continuous real-time ultrasound (US) guidance, until its tip reached near the central part of the tumor. It has retractable curved electrodes and an insulated 17 G outer needle that houses 10 solid retractable curved electrodes that, when deployed, assume the configuration of an umbrella. The electrodes are manufactured in different lengths (2–5 cm umbrella diameter). The alternating electric current generator is 200 W operated at 480 kHz (RF 3000; Boston Scientific, Natick, Massachusetts, USA). The ablation algorithm is based on tissue impedance, and ablation is considered successful if the device impedes out. Grounding was performed by attaching four grounding pads; two pads were attached to each thigh. After the RF procedure was completed, the hooked electrodes were withdrawn and the track was cauterized along its length up to just below the liver capsule to prevent possible tumor seeding or bleeding.

MWA was performed using the HS AMICA (Hs-Hospital Service Spa, Aprilia, Italy) MW system composed of one AMICA probe, which has 11, 14, or 16 G. Inside the probe shaft, there are dual channels through which saline solution is circulated by a built-in AMICA pump to cool the shaft continuously, and one AMICA generator, which can produce power output up to 100 W continuous wave at 2450 MHz.

Under real-time US guidance, the AMICA probe was introduced percutaneously into the tumor with its tip placed in the deepest part of the tumor. The time of the ablation and the power of the generator were adjusted according to the size of the lesion. To prevent possible tumor seeding or bleeding, the needle track was cauterized when withdrawing the probe.

Anesthesia

The ablation procedures were performed under local anesthesia with 1% lidocaine and conscious analgesia-sedation in a well-prepared operating room in the presence of an anesthesiologist.

Image guidance system

Siemens (Sonoline Sienna; Siemens, Munich, Germany) US with a 3.5 MHz curved convex probe was used to guide and monitor the thermal ablation procedures.

Therapeutic efficacy assessment and follow-up were carried out.

All patients underwent contrast-enhanced CT scanning 1 month after treatment to evaluate the effectiveness of the ablation procedures. Ablation was rated as complete when CT scans showed no contrast enhancement inside the lesion in the arterial phase. The ablation was rated as partial when CT scans showed areas of enhancement within the boundaries of the original lesion in the arterial phase. Additional RFA or MWA was performed for tumors with partial ablation (PA).

All completely ablated tumors were regularly followed up at our hepatology unit in the outpatient clinic every 3 months for 18 months using contrast-enhanced triphasic CT to evaluate the efficacy of thermal ablation. Local tumor progression (LTP) was defined as the reappearance of tumor enhancement inside or adjacent to the ablated tumor, and distant recurrence (DR) was defined as new presence of intrahepatic HCC [14].

For patients with LTP or DR who still met the percutaneous ablation inclusion criteria, RFA or MWA was recommended. If patients did not meet the inclusion criteria, transarterial chemoembolization, or conservative treatment was recommended.

Statistical analysis

Continuous results were reported as the mean±SD. Student’s t-test was used for comparison of the liver function and blood count 2–4 days before and 72 h after ablation. The χ2-test or Fisher’s exact probability was used for comparing the rates of complete ablation (CA), PA, LTP, and DR between RFA and MWA. A two-tailed P-value of 0.05 was considered statistically significant. Data analyses were performed using statistical package for the social sciences 10.0 (SPSS; SPSS Inc., Chicago, Illinois, USA).


  Results Top


In our study, 130 HCC patients were randomly managed either using RF (n=70) or MWA (n=60) therapy and were prospectively followed up for detection of the therapeutic efficacy of both procedures.

The results of our study showed that there was no significant difference between the two groups as regards sex, age, tumor size, number of tumors in each patient, underlying cause of liver cirrhosis, and Child–Pugh classification ([Table 1]).

We assessed the success rates of both procedures. For lesions lower to 3 cm, CA was achieved in 86.6 and 91.6% of tumors managed with RFA and MWA techniques, respectively, without statistically significant difference (P=0.7981). However, this difference was significant in lesions 3.1–4 cm (33.3 and 85.7%, respectively, P=0.0388) ([Table 3]).
Table 3 Success rate of both procedures

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As regards PA rate it was higher with RF ablation than with MW ablation in lesions lower to 3 cm but without significance (13.3 and 8.3%, respectively, P=0.5843). However, this difference was statistically significant in lesions measuring 3.1–4 cm in diameter (66.6 and 14.2%, respectively, P=0.0045) ([Table 3]).

We found that AST and ALT levels were significantly elevated at 3 days after both RF ablation and MW ablation compared with the baseline levels (P≤0.0001). The increase in the AST and ALT levels was significantly larger in the MW ablation group than in the RF ablation group (P=0.0006 and 0.0008, respectively). There were no significant alterations in the total bilirubin and albumin levels in both RF and MW ablation patients compared with baseline data.

During the 18-month follow-up period for tumors lower to 3 cm in diameter in both groups, LTP was noticed in 21% of tumors in the RF group and in 13% in the MW group without significant difference (P=0.1944), whereas for large tumors of 3.1–4 cm in diameter LTP was noticed in 33% of tumors in the RF group and in 11% in the MW group with a significant difference (P=0.0387). Tumor DR was noticed in 42.8% of patients in the RF group (30 patients) and 41.6% of patients in the MW group (25 patients) with a nonsignificant difference (P=1.0000) ([Table 4]).
Table 4 Follow-up of studied patients

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  Discussion Top


In recent times, thermal ablation therapy has been increasingly accepted due to the advantages of greater capacity to devitalize HCC with fewer treatment sessions. Among them, RFA and MWA are the most commonly used modalities. In this study, we tried to compare the two methods in terms of therapeutic efficacy. Our patients were randomly divided into two groups: group I, which included 70 patients with 105 hepatic focal lesions proved to be HCC and were treated with RFA, and group II, which included 60 patients with 95 hepatic focal lesions proved to be HCC, and this group was treated with MWA.

As regards the ablative effect of both procedures on laboratory variables, our results are consistent with those of Zhang et al. [5] and Qian et al. [15], as in our study AST and ALT levels were significantly elevated at 72 h in patients after both RF ablation and MW ablation compared with the baseline levels, and the increase in the AST and ALT levels was greater in the MW ablation group than in the RF ablation group.

As regards CA of tumors, our results showed that the number of CA tumors with MW was significantly higher than that in the RF group if tumors were 3.1–4 cm in diameter. However, this difference did not reach a significant level in smaller tumors lower to 3 cm. At the same time, the number of PA tumors using MW was significantly less than that in the RF group if tumors were 3.1–4 cm in diameter. However, this difference did not reach a significant level in smaller tumors lower to 3 cm. From these results we can conclude that MW is superior to RF in HCC treatment, especially large lesions.

These results are consistent with the meta-analysis performed by Facciorusso et al. [16], which included one randomized controlled trial and six retrospective studies comparing MW and RF and concluded that there is a similar efficacy between the two percutaneous techniques with an apparent superiority of MWA in larger neoplasms. However, our results are contradictory to those of Ohmoto et al. [17], who compared the therapeutic effects of RF ablation versus MW ablation in small HCC and found that RFA is more useful compared with MWA.During the 18-month follow-up period, our study revealed that the number of tumors showing LTP in the MW group was significantly less than that in the RF group in tumors measuring 3.1–4 cm in diameter. However, this difference did not reach a significant level in smaller tumors lower to 3 cm. These results are in agreement with those of Abdelaziz et al. [18], who found a lower incidence of HCC recurrence in the MW group when compared with the RF group. However, Ohmoto et al. [17] found superiority for RF as regards local recurrence.

As regards distant tumor recurrence, we did not find any significant difference between the two studied therapeutic modalities. These findings are similar to those of Zhang et al. [5], Shibata et al. [19], and Qian et al. [15], who studied the therapeutic efficacy of MW versus RF in HCC and revealed that there were no significant differences in CA, LTP, and DR between the two groups. Xu et al. [14] concluded that thermal ablation therapy by means of MW and RF energy application is an effective and safe therapeutic technique for HCC. Large tumors can be completely ablated, but have a significantly higher risk for local recurrence at follow-up.


  Conclusion Top


This study suggests that RF ablation and MW ablation are both effective procedures for the treatment of HCC with superiority for MW ablation over RF ablation, especially large one.

Recommendations

Screening program every 3 months to patients at risk for early detection of HCCs amenable to ablation is recommended. Moreover, comparative study should be performed to compare various RF devices to various MW devices trying to obtain better results such as local effectiveness, feasibility, and safety.

Acknowledgements

The authors thank all participants who helped during this study.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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  [Table 1], [Table 2], [Table 3], [Table 4]



 

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