Percutaneous microwave ablation for hepatocellular carcinoma adjacent to large vessels: A long-term follow-up

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Abstract

Purpose

To retrospectively evaluate the effectiveness and safety of ultrasound (US)-guided percutaneous microwave ablation (MWA) in the treatment of hepatocellular carcinoma (HCC) adjacent to large vessels.

Materials and methods

From February 2006 to February 2013, 452 patients with 605 HCC nodules were treated with US-guided percutaneous MWA. Into large vessels group (Group L), 139 patients with 163 lesions (diameter, 1.0–7.0 cm; mean, 2.5 ± 1.1 cm) located less than 5 mm away from large vessels were enrolled. And 313 patients with 442 lesions (diameter, 1.0–8.0 cm; mean, 2.5 ± 1.2 cm) located more than 5 mm away from hepatic surface, large vessels, gallbladder and gastrointestinal tract were included in control group (Group C). During the ablation, the temperature of marginal ablation tissues was monitored and controlled.

Results

The median follow-up time was 24.5 months (range 2.1–87.7 months) in Group L, and 25.7 months (range 1.6–93.9 months) in Group C. Technical effectiveness was achieved in 157 of 163 (96.3%) tumors in Group L and 429 of 442 (97.1%) tumors in Group C, respectively (p > 0.05). The 1-, 3- and 5-year local tumor progression rates and the 1-, 3- and 5-year accumulative survival rates in the two groups have no significantly statistical differences. In addition, no immediate or periprocedural major complications, no delayed complication of vessels or bile ducts injury were found in both of the two groups.

Conclusions

With strict temperature monitoring, US-guided percutaneous MWA is an efficient and safe technology in treating hepatocellular carcinoma adjacent to large vessels.

Introduction

Hepatocellular carcinoma (HCC) is the fifth frequently diagnosed cancer worldwide and is the second main cause in the cancer-related deaths [1]. It was reported that 695,900 cancer deaths occurred all over the world in 2008, and half of these deaths were estimated to occur in China [1], [2]. Improvement in abdominal imaging has made early diagnosis of HCC more easily [3]. Traditionally, hepatic resection is the first-line treatment option for patients who are with solitary tumors and well-preserved liver function [3], [4], [5]. However, resection also has limitations if it is used to treat HCC patients with unfavorable tumor locations. As report goes, resections for malignant zones close to main hepatic veins or the vena cava are sometimes practicable[6], [7], but they are always associated with increased risks [8].

The emergence of local thermal ablation provides a feasible choice for these patients [9], [10], [11], [12], [13]. Minimally invasive percutaneous local ablation techniques, such as radiofrequency ablation (RFA), cryoablation and microwave ablation (MWA), have already been suggested as alternatives for the treatment of HCC [3]. And these techniques referred before, in treating small HCC, were turned out to be promising in clinical results [9], [10], [11]. However, an important inherent effect of heat-sink on thermal ablation may influence the treatment result for the tumors adjacent to large vessels (≥3 mm) [14].

At present, some researchers have already put RFA into practice of treating liver tumors adjacent to large vessels. And the result is satisfying [15], [16], [17]. However, as another kind of thermal ablation techniques, MWA has its special features. It destroys the tumors via high temperature produced by rotating adjacent polar water molecules in the targeted pathologic tissues through electromagnetic energy, which would lead to protein denaturation, cell membrane disruption, and finally coagulation necrosis with cellular death. Under the condition of giving 4–6 min treatment for patients with temperature being greater than 50 °C or reaching 60 °C immediately, the changes described before would appear [18], [19]. MWA has several theoretical advantages over RFA. First, it would produce consistently higher intratumoral temperatures, larger ablation zones, less ablation time and less dependence on the electrical conductivities of tissue. Second, energy delivery is less limited by the exponentially rising electrical impedance of tumor tissue [19], [20], [21], [22]. These advantages may make MWA treatment less affected by heat-sink [21]. Although MWA has been widely used in liver cancer therapy [10], there are no authoritative clinical achievements but only some foundational reports on the effects of treating the tumors adjacent to large vessels [23].

This study aims to assess the effectiveness, safety and clinical outcomes of US-guided MWA in treating patients with HCC adjacent to large vessels.

Section snippets

Patients

This retrospective study was approved by the institutional review board of Chinese PLA General Hospital. Written informed consent for this procedure was obtained from all the enrolled patients. From February 2006 to February 2013, 452 consecutive patients (605 lesions) with HCC were enrolled and underwent percutaneous MWA treatment at this department. Among the 452 patients, 139 patients with 163 HCC lesions, located less than 5 mm from large vessels (large vessels were defined as the first or

Pretreatment clinical parameters

US-guided MWA was performed for 605 HCC nodules in 452 patients. Of 139 patients with 163 lesions closed to large vessels, 104 patients were infected with Hepatitis B and 24 patients with Hepatitis C. In the control group, 252 patients were infected with Hepatitis B and 46 patients with Hepatitis C. The size of lesions ranged from 1 to 7 cm (mean maximum diameter 2.5 ± 1.1 cm) in Group L and 1 to 8 cm (mean maximum diameter 2.5 ± 1.2 cm) in Group C (p > 0.05). The clinical features of patients and tumors

Discussion

RF ablation remains to be the most widely used ablative technique worldwide for liver tumors and it achieved optimistic effectiveness in treating the tumors adjacent to large vessels. Compared with RFA, MWA may provide larger ablation zones and higher intratumoral temperatures. In addition, MWA is also less affected by the heat-sink effect [21]. Therefore, theoretically speaking, the advantages of MWA in dealing with that kind of tumors could get an ideal therapeutic effect. This study aimed to

Conclusion

With strict temperature monitoring, US-guided percutaneous microwave ablation in treating hepatocellular carcinoma adjacent to large vessels is safe and effective.

Conflict of interest

None.

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    1

    These authors contributed equally to the manuscript.

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