Microwave thermal ablation for hepatocarcinoma: six liver transplantation cases

Egyptian Society of Liver Cancer Recommendation Guidelines for the Management of Hepatocellular Carcinoma

Globally, hepatocellular carcinoma (HCC) is the fourth most common cause of death from cancer. The prevalence of this pathology, which has been on the rise in the last 30 years, has been predicted to continue increasing. HCC is the most common cause of cancer-related morbidity and mortality in Egypt and is also the most common cancer in males. Chronic liver diseases, including chronic hepatitis C, which is a primary health concern in Egypt, are considered major risk factors for HCC. However, HCC surveillance is recommended for patients with chronic hepatitis B virus (HBV) and liver cirrhosis; those above 40 with HBV but without cirrhosis; individuals with hepatitis D co-infection or a family history of HCC; and Nonalcoholic fatty liver disease (NAFLD) patients exhibiting significant fibrosis or cirrhosis. Several international guidelines aid physicians in the management of HCC. However, the availability and cost of diagnostic modalities and treatment options vary from one country to another. Therefore, the current guidelines aim to standardize the management of HCC in Egypt. The recommendations presented in this report represent the current management strategy at HCC treatment centers in Egypt. Recommendations were developed by an expert panel consisting of hepatologists, oncologists, gastroenterologists, surgeons, pathologists, and radiologists working under the umbrella of the Egyptian Society of Liver Cancer. The recommendations, which are based on the currently available local diagnostic aids and treatments in the country, include recommendations for future prospects.

Pulsed Microwave Liver Ablation: An Additional Tool to Treat Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma (HCC) is the seventh most frequent neoplasm and the second most common oncologic cause of death, mostly in patients with end-stage liver disease. HCC treatment is complex and different solutions are available, ranging from liver transplants to local therapies. In this study, we analyze the role of pulsed microwave liver ablation as an additional treatment option.

Abstract

This study aimed to analyze the outcomes of HCC patients treated with a novel technique—pulsed microwave ablation (MWA)—in terms of safety, local tumor progression (LTP), intrahepatic recurrence (IHR), and overall survival (OS). A total of 126 pulsed microwave procedures have been performed in our center. We included patients with mono- or multifocal HCC (BCLC 0 to D). The LTP at 12 months was 9.9%, with an IHR rate of 27.8% at one year. Survival was 92.0% at 12 months with 29.4% experiencing post-operative complications (28.6% Clavien–Dindo 1–2, 0.8% Clavien–Dindo 3–4). Stratifying patients by BCLC, we achieved BCLC 0, A, B, C, and D survival rates of 100%, 93.2%, 93.3%, 50%, and 100%, respectively, at one year, which was generally superior to or in line with the expected survival rates among patients who are started on standard treatment. The pulsed MWA technique is safe and effective. The technique can be proposed not only in patients with BCLC A staging but also in the highly selected cases of BCLC B, C, and D, confirming the importance of the concept of stage migration. This procedure, especially if performed with a minimally invasive technique (laparoscopic or percutaneous), is repeatable with a short postoperative hospital stay.

Locoregional Treatments for Bridging and Downstaging HCC to Liver Transplantation

Liver transplantation (LT) is the first-line treatment for patients diagnosed with unresectable early-stage hepatocellular carcinoma (HCC) in the setting of cirrhosis. It is well known that HCC patients within the Milan criteria (solitary tumour ≤ 5 cm or ≤3 tumours, each <3 cm) could undergo LT with excellent results. However, there is a growing tendency to enlarge inclusion criteria since the Milan criteria are nowadays considered too restrictive and may exclude patients who would benefit from LT. On the other hand, there is a persistent shortage of donor organs. In this scenario, there is consensus about the role of loco-regional therapy (LRT) during the waiting list to select patients who would benefit more from LT, reducing the risk of drop off from the waiting list as well as decreasing tumour dimension to meet acceptable criteria for LT. In this review, current evidence on the safety, efficacy and utility of LRTs as neoadjuvant therapies before LT are summarized.

A review on radiofrequency, microwave and high-intensity focused ultrasound ablations for hepatocellular carcinoma with cirrhosis

Importance

Hepatocellular carcinoma (HCC) is usually accompanied by liver cirrhosis, which makes treatment of this disease challenging. Liver transplantation theoretically provides an ultimate solution to the disease, but the maximal surgical stress and the scarcity of liver graft make this treatment option impossible for some patients. In an ideal situation, a treatment that is safe and effective should provide a better outcome for patients with the dilemma.

Objective

This article aims to give a comprehensive review of various types of loco-ablative treatment for HCC.

Evidence Review

Loco-ablative treatment bridges the gap between surgical resection and transarterial chemotherapy. Various types of ablative therapy have their unique ability, and evidence-based outcome analysis is the most important key to assisting clinicians to choose the most suitable treatment modality for their patients.

Findings

Radiofrequency ablation (RFA) has a relatively longer history and more evidence to support its effectiveness. Microwave ablation (MWA) is gaining momentum because of its shorter ablation time and consistent ablation zone. High-intensity focused ultrasound (HIFU) ablation is a relatively new technology that provides non-invasive treatment for patients with HCC. It has been carried out at centers of excellence and it is a safe and effective treatment option for selected patients with HCC and liver cirrhosis.

Conclusion and Relevance

Selective use of different loco-ablative therapies will enhance clinicians' treatment options for treatment of HCC.

Thoracoscopic Ablation of Critically Located Liver Tumors: A Safety and Efficacy Cohort Study

Background: Liver resection represents the first curative treatment to treat primary and secondary hepatic tumors. Thoracoscopic liver ablation is a viable and minimally invasive alternative treatment, especially for patients with previous multiple abdominal surgeries. The aim of the study was to evaluate the safety and efficacy of thoracoscopic ablation for liver tumors. Methods: Retrospective analysis of a prospective database of patients with liver tumors, treated with thoracoscopic trans-diagrammatic ablation (MWA or RFA) at our institution from 2012 to 2018. The primary endpoint was post-operative mortality at 30 days, while secondary endpoints were morbidity and efficacy of ablation (i.e., response rate evaluated according to mRECIST criteria, and overall patient survival). Patient demographics, operational characteristics, and complications were recorded. Results: A total of 13 nodules were treated in 10 patients with a median age of 65.5 years. Post-operative mortality was 0%, and overall morbidity was 40% (Clavien-Dindo I complications 30%, II 0%, III 10%, IV 0%). Complete radiological response was obtained in 83.3% of nodules at 3 months. After a median follow-up of 20.95 months, the local tumor progression rate was 30%, with an intra-segmental-recurrence of 30%, and an intra-hepatic-recurrence of 30%. The overall 1-, 2-, and 3-years survival rates were 80%, 58%, and 58%. Conclusion: Thoracoscopic trans-diaphragmatic ablation proved to be a safe and effective way to treat liver tumors when abdominal approach is not feasible. Considering the low morbidity, it is a viable option to treat patients with recurrent disease and/or previous multiple abdominal surgeries.

Histological Correlation for Radiofrequency and Microwave Ablation in the Local Control of Hepatocellular Carcinoma (HCC) before Liver Transplantation: A Comprehensive Review

Simple Summary

Liver cancer is a growing problem around the world. Drugs for liver cancer have limited effect, there are not enough donors for liver transplants and many patients are not candidates for surgery to remove the tumor. In many of these cases, hyperthermia can destroy the tumor in situ with minimally invasive methods such as radiofrequency or microwave ablation. In this paper we review the literature evaluating success rates for complete ablation as judged by actual examination of treated tumors that were removed when patients received a liver transplant. While notable successes can be achieved with ablation, the published studies indicate both that complete treatment is not as common as thought and that imaging methods such as computed tomography and magnetic resonance scans do not completely identify residual cancer. There is therefore an important opportunity for improvement in the treatment of this disease.

Abstract

Radiofrequency ablation (RFA) and microwave ablation (MWA) are the most widely studied and applied ablation techniques for treating primary and secondary liver tumors. These techniques are considered curative for small hepatic tumors, with post-ablation outcomes most commonly assessed by an imaging follow up. However, there is increasing evidence of a discrepancy between radiological and pathological findings when ablated lesions are evaluated following liver resection or liver transplantation. A comprehensive review of the available literature reporting the complete pathological response (cPR) following RFA and MWA was performed to estimate the success rate and identify the factors associated with treatment failure. Following RFA, cPR is reported in 26–96% of tumors compared to 57–95% with MWA. Larger tumor size and vessels larger than 3 mm adjacent to the treated tumor are the most important factors identified by previous studies associated with viable residual tumors after RFA. Correlating post-ablation radiological studies with pathological findings shows that computed tomography (CT) and magnetic resonance imaging (MRI) have low sensitivity but high specificity for detecting residual viable or recurrent hepatocellular carcinoma (HCC) tumors. There are promising recent reports combining multiprobe ablation techniques with three-dimensional treatment planning software and stereotactic-aiming instrumentation to achieve more than 90% cPR in both small and large HCC tumors. In conclusion, the reported success for achieving cPR in HCC following RFA and MWA is highly variable in different studies and decreases with increasing lesion size and unfavorable tumor characteristics. Very few studies have reported a high rate of cPR. As these studies are single-center and retrospective, they need to be further validated and reproduced in other clinical settings.

Radiofrequency Ablation and Microwave Ablation in Liver Tumors: An Update

This article provides an overview of radiofrequency ablation (RFA) and microwave ablation (MWA) for treatment of primary liver tumors and hepatic metastasis. Only studies reporting RFA and MWA safety and efficacy on liver were retained. We found 40 clinical studies that satisfied the inclusion criteria. RFA has become an established treatment modality because of its efficacy, reproducibility, low complication rates, and availability. MWA has several advantages over RFA, which may make it more attractive to treat hepatic tumors. According to the literature, the overall survival, local recurrence, complication rates, disease-free survival, and mortality in patients with hepatocellular carcinoma (HCC) treated with RFA vary between 53.2 ± 3.0 months and 66 months, between 59.8% and 63.1%, between 2% and 10.5%, between 22.0 ± 2.6 months and 39 months, and between 0% and 1.2%, respectively. According to the literature, overall survival, local recurrence, complication rates, disease-free survival, and mortality in patients with HCC treated with MWA (compared with RFA) vary between 22 months for focal lesion >3 cm (vs. 21 months) and 50 months for focal lesion ≤3 cm (vs. 27 months), between 5% (vs. 46.6%) and 17.8% (vs. 18.2%), between 2.2% (vs. 0%) and 61.5% (vs. 45.4%), between 14 months (vs. 10.5 months) and 22 months (vs. no data reported), and between 0% (vs. 0%) and 15% (vs. 36%), respectively. According to the literature, the overall survival, local recurrence, complication rates, and mortality in liver metastases patients treated with RFA (vs. MWA) are not statistically different for both the survival times from primary tumor diagnosis and survival times from ablation, between 10% (vs. 6%) and 35.7% (vs. 39.6), between 1.1% (vs. 3.1%) and 24% (vs. 27%), and between 0% (vs. 0%) and 2% (vs. 0.3%). MWA should be considered the technique of choice in selected patients, when the tumor is ≥3 cm in diameter or is close to large vessels, independent of its size. IMPLICATIONS FOR PRACTICE: Although technical features of the radiofrequency ablation (RFA) and microwave ablation (MWA) are similar, the differences arise from the physical phenomenon used to generate heat. RFA has become an established treatment modality because of its efficacy, reproducibility, low complication rates, and availability. MWA has several advantages over RFA, which may make it more attractive than RFA to treat hepatic tumors. The benefits of MWA are an improved convection profile, higher constant intratumoral temperatures, faster ablation times, and the ability to use multiple probes to treat multiple lesions simultaneously. MWA should be considered the technique of choice when the tumor is ≥3 cm in diameter or is close to large vessels, independent of its size.

Liver transplantation for hepatocellular carcinoma: Where do we stand?

Hepatocellular carcinoma represents an important cause of morbidity and mortality worldwide. It is the sixth most common cancer and the fourth leading cause of cancer death. Liver transplantation is a key tool for the treatment of this disease in human therefore hepatocellular carcinoma is increasing as primary indication for grafting. Although liver transplantation represents an outstanding therapy for hepatocellular carcinoma, due to organ shortage, the careful selection and management of patients who may have a major survival benefit after grafting remains a fundamental question. In fact, only some stages of the disease seem amenable of this therapeutic option, stimulating the debate on the appropriate criteria to select candidates. In this review we focused on current criteria to select patients with hepatocellular carcinoma for liver transplantation as well as on the strategies (bridging) to avoid disease progression and exclusion from grafting during the stay on wait list. The treatments used to bring patients within acceptable criteria (down-staging), when their tumor burden exceeds the standard criteria for transplant, are also reported. Finally, we examined tumor reappearance following liver transplantation. This occurrence is estimated to be approximately 8%-20% in different studies. The possible approaches to prevent this outcome after transplant are reported with the corresponding results.

Bridging and downstaging therapy in patients suffering from hepatocellular carcinoma waiting on the list of liver transplantation

Hepatocellular carcinoma (HCC) is a common primary malignancy worldwide especially in the patients with the background of chronic liver disease. Liver transplantation (LT) is the only curative treatment effective for both malignancy as well as the cirrhosis and portal hypertension. Unfortunately, living donor is not always possible and the deceased graft is scarce. Neoadjuvant therapies, therefore, have been developed as a downstaging treatment to try to downstage the tumor within the transplant criteria, or as a bridging therapy to control the tumor growth in patients while waiting in the transplant list. This paper reviewed the common modalities used as bridging and downstaging therapies for patients suffering from HCC before undergoing LT.

Microwave ablation of hepatocellular carcinoma

Although surgical resection is still the optimal treatment option for early-stage hepatocellular carcinoma (HCC) in patients with well compensated cirrhosis, thermal ablation techniques provide a valid non-surgical treatment alternative, thanks to their minimal invasiveness, excellent tolerability and safety profile, proven efficacy in local disease control, virtually unlimited repeatability and cost-effectiveness. Different energy sources are currently employed in clinics as physical agents for percutaneous or intra-surgical thermal ablation of HCC nodules. Among them, radiofrequency (RF) currents are the most used, while microwave ablations (MWA) are becoming increasingly popular. Starting from the 90s’, RF ablation (RFA) rapidly became the standard of care in ablation, especially in the treatment of small HCC nodules; however, RFA exhibits substantial performance limitations in the treatment of large lesions and/or tumors located near major heat sinks. MWA, first introduced in the Far Eastern clinical practice in the 80s’, showing promising results but also severe limitations in the controllability of the emitted field and in the high amount of power employed for the ablation of large tumors, resulting in a poor coagulative performance and a relatively high complication rate, nowadays shows better results both in terms of treatment controllability and of overall coagulative performance, thanks to the improvement of technology. In this review we provide an extensive and detailed overview of the key physical and technical aspects of MWA and of the currently available systems, and we want to discuss the most relevant published data on MWA treatments of HCC nodules in regard to clinical results and to the type and rate of complications, both in absolute terms and in comparison with RFA.

Microwave ablation: state-of-the-art review

This paper reviews state-of-the-art microwave ablation (MWA) of tumors. MWA is a novel method for treating inoperable tumors, ie, tumors that cannot be treated surgically. However, patients generally choose removal of the tumor by conventional techniques. A literature review of MWA for breast, liver, lung, and kidney tumors is reported here, with tabulation of our findings according to the type of technique used, with a detailed description of the time, type of microwave generator used, and number of patients treated with MWA. In some cases, the subjects were not human patients, but pig or bovine liver specimens. MWA is a technique that has proved to be promising and likely to be used increasingly in the ablation of cancerous tumors. However, MWA needs to be used more widely to establish itself as a common tool in the treatment of inoperable tumors.

Minimally invasive local therapies for liver cancer

Primary and metastatic liver tumors are an increasing global health problem, with hepatocellular carcinoma (HCC) now being the third leading cause of cancer-related mortality worldwide. Systemic treatment options for HCC remain limited, with Sorafenib as the only prospectively validated agent shown to increase overall survival. Surgical resection and/or transplantation, locally ablative therapies and regional or locoregional therapies have filled the gap in liver tumor treatments, providing improved survival outcomes for both primary and metastatic tumors. Minimally invasive local therapies have an increasing role in the treatment of both primary and metastatic liver tumors. For patients with low volume disease, these therapies have now been established into consensus practice guidelines. This review highlights technical aspects and outcomes of commonly utilized, minimally invasive local therapies including laparoscopic liver resection (LLR), radiofrequency ablation (RFA), microwave ablation (MWA), high-intensity focused ultrasound (HIFU), irreversible electroporation (IRE), and stereotactic body radiation therapy (SBRT). In addition, the role of combination treatment strategies utilizing these minimally invasive techniques is reviewed.

Laparoscopic microwave thermal ablation for late recurrence of local hepatocellular carcinoma after liver transplant: case report

Liver transplant is the preferred treatment for hepatocellular carcinoma in patients with cirrhosis, as both neoplastic and cirrhotic liver tissue can be removed. Treatment of recurring neoplasms is a difficult issue, especially in long-term survivors of liver transplant. No consensus has been reached on the treatment of recurrent hepatocellular carcinoma. Although patients with extrahepatic metastases are generally not candidates for local therapy, successful multimodal salvage therapy including resection or ablation can be achieved in liver transplant recipients with local recurrence of hepatocellular carcinoma. Microwave ablation is safe and effective for treating unresectable hepatocellular carcinoma, achieving excellent results in local disease down-staging or as a "bridge" to liver transplant, with no significant differences in local recurrence and complications compared with the more commonly used radiofrequency ablation. A patient with local recurrence of hepatocellular carcinoma 36 months after liver transplant for multifocal hepatocellular carcinoma and cirrhosis due to hepatitis C was successfully treated with laparoscopic microwave ablation without any postoperative complications. The patient is disease free 24 months after microwave ablation.

Locally ablative therapies for primary and metastatic liver cancer

Locally ablative therapies have an increasing role in the effective multidisciplinary approach towards the treatment of both primary and metastatic liver tumors. In patients who are not considered surgical candidates and have low volume disease, these therapies have now become established into consensus practice guidelines. A large range of therapeutic options exist including percutaneous ethanol injection (PEI), radiofrequency ablation (RFA), microwave ablation (MWA), cryoablation, percutaneous laser ablation (PLA), irreversible electroporation (IRE), stereotactic body radiation therapy (SBRT) and high intensity focused ultrasound (HIFU); each having benefits and drawbacks. The greatest body of evidence supporting clinical utility in the liver currently exists for RFA, with PEI having fallen out of favor. MWA, IRE, SBRT and HIFU are relatively nascent technologies, and outcomes data supporting their use is promising. Future directions of ablative therapies include tandem approaches to improve efficacy in the treatment of liver tumors.

Histopathologic comparison of monopolar versus no-touch multipolar radiofrequency ablation to treat hepatocellular carcinoma within Milan criteria

PURPOSE

To compare histopathologically the completeness of radiofrequency (RF) ablation to treat hepatocellular carcinoma (HCC) with monopolar or multipolar technique.

MATERIALS AND METHODS

Thirty-five consecutive patients (mean age, 59 y) with cirrhosis and HCC (n = 59) within Milan criteria received RF ablation and subsequently underwent liver transplantation (LT) for tumor progression or liver failure. Data were extracted retrospectively from a prospective database. Thirty nodules were treated with a monopolar device with internally cooled (n = 17) or perfused (n = 13) electrodes, and 29 were treated with a multipolar technique with internally cooled electrodes based on the "no-touch" concept. This consisted of inserting two or three straight electrodes around the nodule to avoid intratumor puncture to the greatest extent possible. Effectiveness of the three devices was compared by histopathologic examination of explants. Fisher exact and χ(2) tests and multivariate logistic regression analysis were performed.

RESULTS

Mean sizes of nodules ablated (25, 22, and 21.6 mm) and median times from ablation to LT (11, 7.5, and 8.4 months) for patients treated with the monopolar internally cooled electrode device (MoICD), monopolar perfused electrode device (MoPED), and multipolar internally cooled electrode device (MuICD), respectively, were similar (P = .8 and P = .9, respectively). Pathologic examination showed complete necrosis for eight of 17 and six of 13 nodules treated with the MoICD and MoPED, respectively, versus 26 of 29 treated with the MuICD (P = .0019). In multivariate analysis, RF technique remained the predictive factor for complete necrosis (P = .005).

CONCLUSIONS

Ablation of small HCCs with multipolar RF ablation based on the no-touch concept improves the rate of complete necrosis during pathologic examination compared with monopolar techniques.

Microwave ablation using 915-MHz and 2.45-GHz systems: what are the differences?

OBJECTIVES

This study was conducted to evaluate differences between 915-MHz and 2.45-GHz microwave ablation (MWA) systems in the ablation of hepatic tumours.

METHODS

A retrospective analysis of patients undergoing hepatic tumour MWA utilizing two different systems over a 10-month period was carried out.

RESULTS

Data for a total of 48 patients with a mean age of 58 ± 1.24 years were analysed. A total of 124 tumours were ablated; 72 tumours were ablated with a 915-MHz system and 52 with a 2.45-GHz system. Mean tumour diameters were 1.7 ± 0.1 cm in the 915-MHz group and 2.5 ± 0.2 cm in the 2.45-GHz group (P < 0.01). Mean ablation time per burn was 8.1 ± 0.3 min in the 915-MHz group and 4.0 ± 0.1 min in the 2.45-GHz group (P < 0.01). The mean number of burns per lesion was 2.0 ± 0.1 in the 915-MHz group and 1.7 ± 0.1 in the 2.45-GHz group (P < 0.05). The mean ablation time per lesion was 9.7 ± 0.7 min in the 915-MHz group, and 6.6 ± 0.6 min in the 2.45-GHz group (P < 0.01). The 2.45-GHz system demonstrated a better correlation between ablation time and tumour size (r(2) = 0.6222) than the 915-MHz system; (r(2) = 0.0696). Mean total energy applied per lesion, and energy applied per cm, were greater with the 915-MHz system (P < 0.05 and P < 0.01, respectively). Total energy applied per lesion was similarly correlated for the 2.45-GHz (r(2) = 0.6263) and 915-MHz (r(2) = 0.7012) systems. Mean total energy applied per cm/min was greater with the 2.45-GHz system (P < 0.05).

CONCLUSIONS

Both 915-MHz and 2.45-GHz MWA systems achieve reproducible hepatic tumour ablation. The 2.45-GHz system achieves equivalent, but more predictable and faster ablations using a single antenna system.

Bridging and downstaging treatments for hepatocellular carcinoma in patients on the waiting list for liver transplantation

Several therapeutic procedures have been proposed as bridging treatments for patients with hepatocellular carcinoma (HCC) awaiting liver transplantation (LT). The most used treatments include transarterial chemoembolization and radiofrequency ablation. Surgical resection has also been successfully used as a bridging procedure, and LT should be considered a rescue treatment in patients with previous HCC resection who experience tumor recurrence or post-treatment severe decompensation of liver function. The aims of bridging treatments include decreasing the waiting list dropout rate before transplantation, reducing HCC recurrence after transplantation, and improving post-transplant overall survival. To date, no data from prospective randomized studies are available; however, for HCC patients listed for LT within the Milan criteria, prolonging the waiting time over 6-12 mo is a risk factor for tumor spread. Bridging treatments are useful in containing tumor progression and decreasing dropout. Furthermore, the response to pre-LT treatments may represent a surrogate marker of tumor biological aggressiveness and could therefore be evaluated to prioritize HCC candidates for LT. Lastly, although a definitive conclusion can not be reached, the experiences reported to date suggest a positive impact of these treatments on both tumor recurrence and post-transplant patient survival. Advanced HCC may be downstaged to achieve and maintain the current conventional criteria for inclusion in the waiting list for LT. Recent studies have demonstrated that successfully downstaged patients can achieve a 5-year survival rate comparable to that of patients meeting the conventional criteria without requiring downstaging.

Microwave ablation devices for interventional oncology

Microwave ablation is one of the several options in the ablation armamentarium for the treatment of malignancy, offering several potential benefits when compared with other ablation, radiation, surgical and medical treatment modalities. The basic microwave system consists of the generator, power distribution system and antennas. Often under image (computed tomography or ultrasound) guidance, a needle-like antenna is inserted percutaneously into the tumor, where local microwave electromagnetic radiation is emitted from the probe's active tip, producing frictional tissue heating, capable of causing cell death by coagulation necrosis. Half of the microwave ablation systems use a 915 MHz generator and the other half use a 2450 MHz generator. To date, there are no completed clinical trials comparing microwave devices head-to-head. Prospective comparisons of microwave technology with other treatment alternatives, as well as head-to-head comparison with each microwave device, is needed if this promising field will garner more widespread support and use in the oncology community.

Resection vs thermal ablation of small hepatocellular carcinoma: What's the first choice?

Nowadays, hepatocellular carcinoma (HCC) is frequently diagnosed at an early stage, opening good perspectives to radical treatment by means of liver transplantation, surgical resection, or percutaneous ablation. Liver transplantation is considered the best option, but the lack of liver donors represents a major limitation. Therefore, surgical resection, offering a 5-year-survival rate of over 50%, is considered the first-choice treatment for patients with early stage HCC, whereas percutaneous ablation is usually reserved to patients who are not candidate to surgery. However, in the recent years some trials showed that percutaneous radiofrequency ablation (RFA) can be as effective as surgical resection in terms of overall survival and recurrence-free survival rates in patients with small HCC, and a retrospective comparative study reported 1-, 3-, and 5-year overall survival rates and recurrence-free survival rates significantly better in patients with central HCC measuring 2 cm or smaller treated with RFA than in those treated with surgical resection. RFA is less expensive, less invasive, with lower complication rate and shorter hospital stay than surgical resection, and on the basis of the results of these studies it should be considered the first option in the treatment of very early HCC. However, RFA is size-dependent, so at present the need to achieve an adequate safety margin around the tumor limits to about 2 cm the diameter of the nodules that can be ablated with long-term outcomes comparable to or better than surgical resection. The main goal of the next technical developments of the thermal ablation systems should be the achievement of larger ablation areas with a single needle insertion. In this regard, the recent improvements in microwave energy delivery systems seem to open interesting perspectives to percutaneous microwave ablation, which could become the ablation technique of choice in the next future.

Complications of microwave ablation for liver tumors: results of a multicenter study

PURPOSE

New technologies for microwave ablation (MWA) have been conceived, designed to achieve larger areas of necrosis compared with radiofrequency ablation (RFA). The purpose of this study was to report complications by using this technique in patients with focal liver cancer.

METHODS

Members of 14 Italian centers used a 2.45-GMHz generator delivering energy through a cooled miniature-choke MW antenna and a standardized protocol for follow-up. They completed a questionnaire regarding number and type of deaths, major and minor complications and side effects, and likelihood of their relationship to the procedure. Enrollment included 736 patients with 1.037 lesions: 522 had hepatocellular carcinoma with cirrhosis, 187 had metastases predominantly from colorectal cancer, and 27 had cholangiocellular carcinoma. Tumor size ranged from 0.5 to 10 cm. In 13 centers, the approach used was percutaneous, in 4 videolaparoscopic, and in 3 laparotomic.

RESULTS

No deaths were reported. Major complications occurred in 22 cases (2.9%), and minor complications in 54 patients (7.3%). Complications of MWA do not differ from those RFA, both being based on the heat damage.

CONCLUSION

Results of this multicenter study confirmed those of single-center experiences, indicating that MWA is a safe procedure, with no mortality and a low rate of major complications. The low rate of complications was probably due to precautions adopted, knowing in advance possible risk conditions, on the basis of prior RFA experience.