Comparison of microwave ablation and surgical resection for treatment of hepatocellular carcinomas conforming to Milan criteria

Efficacy evaluation of postoperative adjuvant transarterial chemoembolization in preventing hepatocellular carcinoma recurrence within the Milan criteria: A multicenter propensity score matching analysis based on pathologic indicators

BACKGROUND

Malignant biologic behaviors, such as microvascular invasion (MVI), satellite nodule formation, and poor differentiation, can appear in the postoperative pathology of early hepatocellular carcinoma (HCC), which often indicates an earlier stage of malignant evolution. This study aimed to evaluate tumor recurrence in patients with HCC meeting the Milan criteria who underwent postoperative adjuvant transarterial chemoembolization (PA-TACE) according to postoperative pathologic indices.

METHODS

A retrospective study was conducted on 790 patients with HCC meeting the Milan criteria who underwent hepatectomy across 4 medical centers, consisting of 366 patients treated with PA-TACE and 424 patients treated without PA-TACE. To reduce selection bias, propensity score matching (PSM) at a 1:1 ratio was applied, achieving balanced clinical characteristics between the 2 groups.

RESULTS

Patients who underwent PA-TACE did not experience severe adverse events or toxicity-related deaths. After PSM of each subgroup, it was found that patients with MVI (median time: 37 vs 17 months; P =.010), satellite nodules (median time: Not Applicable [NA] vs 14 months; P =.018), and Edmondson-Steiner grades III and IV (median time: NA vs 13 months; P =.004) who received PA-TACE had higher recurrence-free survival (RFS). However, patients who were MVI negative, satellite nodule negative, and Edmondson-Steiner grades I and II did not benefit from PA-TACE in terms of RFS (all P >.05). Patients who received PA-TACE were more likely to undergo liver transplantation, rehepatectomy, or local ablation after tumor recurrence, whereas those who did not receive PA-TACE were more likely to receive TACE, chemoradiotherapy, or immune-targeted therapy after tumor recurrence (all P<.05).

CONCLUSION

Postoperative pathologic indicators can guide the selection of PA-TACE for patients with HCC meeting the Milan criteria. Patients with MVI, satellite nodules, and Edmondson-Steiner grades III and IV are more suitable for receiving PA-TACE to improve RFS. PA-TACE may alter the recurrence pattern of tumors, rendering them more localized.

Primary treatments for solitary hepatocellular carcinoma ≤ 3 cm: A systematic review and network meta-analysis

Various treatment modalities are available for small solitary hepatocellular carcinoma (HCC), yet the optimal primary treatment strategy for tumors ≤ 3 cm remains unclear. This network meta-analysis investigates the comparative efficacy of various interventions on the long-term outcomes of patients with solitary HCC ≤ 3 cm. A systematic search of electronic databases from January 2000 to December 2023 was conducted to identify studies that compared at least two of the following treatments: surgical resection (SR), radiofrequency ablation (RFA), microwave ablation (MWA), and transarterial chemoembolization (TACE). Survival data were extracted, and pooled hazard ratios with 95% confidence intervals were calculated using a frequentist network meta-analysis. A total of 30 studies, comprising 2 randomized controlled trials and 28 retrospective studies, involving 8,053 patients were analyzed. Surgical resection showed the highest overall survival benefit with a p-score of 0.95, followed by RFA at 0.59, MWA at 0.23, and TACE, also at 0.23. Moreover, SR provided the most significant recurrence-free survival advantage, with a p-score of 0.95, followed by RFA at 0.31 and MWA at 0.19. Sensitivity analyses, excluding low-quality or retrospective non-matched studies, corroborated these findings. This network meta-analysis demonstrates that SR is the most effective first-line curative treatment for single HCC ≤ 3 cm, followed by RFA in patients with preserved liver function. The limited data on MWA and TACE underscore the need for further studies.

Ablative Treatments and Surgery for Early-Stage Hepatocellular Carcinoma: A Network Meta-Analysis

BACKGROUND

We compared overall survival (OS) and disease-free survival (DFS) for hepatocellular carcinoma (HCC) following radiofrequency ablation (RFA), microwave ablation (MWA), cryoablation, and liver resection (LR), with the aim of evaluating treatment plans for early-stage HCC.

METHODS

Studies in PubMed, Web of Science, and Cochrane databases from April 1, 2004, to April 1, 2024, were searched. Articles were evaluated for quality using the randomized controlled trials tool. Two tool and the Newcastle-Ottawa Scale. Data obtained from the literature were netted using Stata 15.0 and r 4.2.3. The assessed primary outcomes were OS and DFS at 1 and 3 y.

RESULTS

A total of 25 publications with 4548 patients were included, including 13 studies in mainland China and 12 in other regions. For 1-y DFS, the hazard ratio (HR) was 0.54 (95% credible interval (CrI): 0.38-0.76) for LR compared with RFA and 0.57 (95% CrI: 0.3--0.82) for LR compared with MWA. For 3-y DFS, the HR was 0.52 (95% CrI: 0.38-0.72) for LR compared with RFA and 0.53 (95% CrI: 0.37-0.76). In the Chinese mainland, LR may have a better 1- and 3-y DFS than MWA, but similar survival to RFA. In the other regions, LR had a better DFS than MWA and RFA patients. The rest of the comparisons were not statistically significant.

CONCLUSIONS

For early-stage HCC, LR may be more effective in reducing tumor recurrence than ablative treatments. Cryoablation may be a potential treatment for HCC. The differences in treatment effectiveness in different regions are worth further study.

Laparoscopic-assisted microwave ablation in treatment of small hepatocellular carcinoma: safety and efficacy in comparison with laparoscopic hepatectomy

Laparoscopic-assisted microwave ablation (LAMWA), as one of the locoregional therapies, has been employed to treat hepatocellular carcinoma (HCC). This study aims to compare the efficacy and safety of LAMWA and laparoscopic hepatectomy in the treatment of small HCC.This study included 140 patients who met the inclusion criteria. Among them, 68 patients received LAMWA and 72 patients underwent laparoscopic hepatectomy. The perioperative condition, liver function recovery, the alpha fetoprotein (AFP) level, morbidities, hospitalization time, overall survival (OS), disease-free survival (DFS) and recurrence rate between the two groups were compared. The rate of complete elimination of tumor tissue was 100% and the AFP level was returned to normal within 3 months after surgery in both groups (P > 0.05). The mean alanine transaminase (ALT) and aspartate transaminase (AST) peak in the LAMWA group was lower than that in the laparoscopic hepatectomy group (259.51 ± 188.75 VS 388.9 ± 173.65, P = 0.000) and (267.34 ± 190.65 VS 393.1 ± 185.67, P = 0.000), respectively. The mean operation time in the LAMWA group was shorter than that in the laparoscopic hepatectomy group (89 ± 31 min VS 259 ± 48 min, P = 0.000). The blood loss in the LAMWA group was less than that in the laparoscopic hepatectomy group (58.4 ± 64.0 ml VS 213.0 ± 108.2 ml, P = 0.000). Compared with the laparoscopic hepatectomy group, patients in the LAMWA group had lower mean hospital stay (4.8 ± 1.2d VS 11.5 ± 2.9d, P = 0.000). The morbidities of the LAMWA group and the hepatectomy group were 14.7%(10/68) and 34.7%(25/72), respectively (P = 0.006). The one-, three-, and five-year OS rates were 88.2%, 69.9%, 45.6% for the LAMWA group and 86.1%, 72.9%, 51.4% for the laparoscopic hepatectomy group (P = 0.693). The corresponding DFS rates for the two groups were 76.3%, 48.1%, 27.9% and 73.2%, 56.7%, 32.0% (P = 0.958). Laparoscopic-assisted microwave ablation is a safe and effective therapeutic option for selected small HCC.

Simulation of Image-Guided Microwave Ablation Therapy Using a Digital Twin Computational Model

Emerging computational tools such as healthcare digital twin modeling are enabling the creation of patient-specific surgical planning, including microwave ablation to treat primary and secondary liver cancers. Healthcare digital twins (DTs) are anatomically one-to-one biophysical models constructed from structural, functional, and biomarker-based imaging data to simulate patient-specific therapies and guide clinical decision-making. In microwave ablation (MWA), tissue-specific factors including tissue perfusion, hepatic steatosis, and fibrosis affect therapeutic extent, but current thermal dosing guidelines do not account for these parameters. This study establishes an MR imaging framework to construct three-dimensional biophysical digital twins to predict ablation delivery in livers with 5 levels of fat content in the presence of a tumor. Four microwave antenna placement strategies were considered, and simulated microwave ablations were then performed using 915 MHz and 2450 MHz antennae in Tumor Naïve DTs (control), and Tumor Informed DTs at five grades of steatosis. Across the range of fatty liver steatosis grades, fat content was found to significantly increase ablation volumes by approximately 29-l42% in the Tumor Naïve and 55-60% in the Tumor Informed DTs in 915 MHz and 2450 MHz antenna simulations. The presence of tumor did not significantly affect ablation volumes within the same steatosis grade in 915 MHz simulations, but did significantly increase ablation volumes within mild-, moderate-, and high-fat steatosis grades in 2450 MHz simulations. An analysis of signed distance to agreement for placement strategies suggests that accounting for patient-specific tumor tissue properties significantly impacts ablation forecasting for the preoperative evaluation of ablation zone coverage.

Ablative and non-surgical therapies for early and very early hepatocellular carcinoma: a systematic review and network meta-analysis

Background

A wide range of ablative and non-surgical therapies are available for treating small hepatocellular carcinoma in patients with very early or early-stage disease and preserved liver function.

Objective

To review and compare the effectiveness of all current ablative and non-surgical therapies for patients with small hepatocellular carcinoma (≤ 3 cm).

Design

Systematic review and network meta-analysis.

Data sources

Nine databases (March 2021), two trial registries (April 2021) and reference lists of relevant systematic reviews.

Review methods

Eligible studies were randomised controlled trials of ablative and non-surgical therapies, versus any comparator, for small hepatocellular carcinoma. Randomised controlled trials were quality assessed using the Cochrane Risk of Bias 2 tool and mapped. The comparative effectiveness of therapies was assessed using network meta-analysis. A threshold analysis was used to identify which comparisons were sensitive to potential changes in the evidence. Where comparisons based on randomised controlled trial evidence were not robust or no randomised controlled trials were identified, a targeted systematic review of non-randomised, prospective comparative studies provided additional data for repeat network meta-analysis and threshold analysis. The feasibility of undertaking economic modelling was explored. A workshop with patients and clinicians was held to discuss the findings and identify key priorities for future research.

Results

Thirty-seven randomised controlled trials (with over 3700 relevant patients) were included in the review. The majority were conducted in China or Japan and most had a high risk of bias or some risk of bias concerns. The results of the network meta-analysis were uncertain for most comparisons. There was evidence that percutaneous ethanol injection is inferior to radiofrequency ablation for overall survival (hazard ratio 1.45, 95% credible interval 1.16 to 1.82), progression-free survival (hazard ratio 1.36, 95% credible interval 1.11 to 1.67), overall recurrence (relative risk 1.19, 95% credible interval 1.02 to 1.39) and local recurrence (relative risk 1.80, 95% credible interval 1.19 to 2.71). Percutaneous acid injection was also inferior to radiofrequency ablation for progression-free survival (hazard ratio 1.63, 95% credible interval 1.05 to 2.51). Threshold analysis showed that further evidence could plausibly change the result for some comparisons. Fourteen eligible non-randomised studies were identified (n ≥ 2316); twelve had a high risk of bias so were not included in updated network meta-analyses. Additional non-randomised data, made available by a clinical advisor, were also included (n = 303). There remained a high level of uncertainty in treatment rankings after the network meta-analyses were updated. However, the updated analyses suggested that microwave ablation and resection are superior to percutaneous ethanol injection and percutaneous acid injection for some outcomes. Further research on stereotactic ablative radiotherapy was recommended at the workshop, although it is only appropriate for certain patient subgroups, limiting opportunities for adequately powered trials.

Limitations

Many studies were small and of poor quality. No comparative studies were found for some therapies.

Conclusions

The existing evidence base has limitations; the uptake of specific ablative therapies in the United Kingdom appears to be based more on technological advancements and ease of use than strong evidence of clinical effectiveness. However, there is evidence that percutaneous ethanol injection and percutaneous acid injection are inferior to radiofrequency ablation, microwave ablation and resection.

Study registration

PROSPERO CRD42020221357.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment (HTA) programme (NIHR award ref: NIHR131224) and is published in full in Health Technology Assessment; Vol. 27, No. 29. See the NIHR Funding and Awards website for further award information.

Local Therapies for Hepatocellular Carcinoma and Role of MRI-Guided Adaptive Radiation Therapy

Hepatocellular carcinoma (HCC) is the most common liver tumor, with a continually rising incidence. The curative treatment for HCC is surgical resection or liver transplantation; however, only a small portion of patients are eligible due to local tumor burden or underlying liver dysfunction. Most HCC patients receive nonsurgical liver-directed therapies (LDTs), including thermal ablation, transarterial chemoembolization (TACE), transarterial radioembolization (TARE), and external beam radiation therapy (EBRT). Stereotactic ablative body radiation (SABR) is a specific type of EBRT that can precisely deliver a high dose of radiation to ablate tumor cells using a small number of treatments (or fractions, typically 5 or less). With onboard MRI imaging, MRI-guided SABR can improve therapeutic dose while minimizing normal tissue exposure. In the current review, we discuss different LDTs and compare them with EBRT, specifically SABR. The emerging MRI-guided adaptive radiation therapy has been reviewed, highlighting its advantages and potential role in HCC management.

Clinical Results, Risk Factors, and Future Directions of Ultrasound-Guided Percutaneous Microwave Ablation for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, with a relatively poor prognosis, especially for advanced HCC. With the availability of a variety of treatment options, the treatment strategies for HCC have become more and more diversified. Microwave ablation (MWA) has gradually been considered as a viable alternative to surgical resection (SR) owing to its comparable long-term survival, reduced complications, and greater preservation of hepatic parenchyma. However, clinical outcomes, tumor progression, and recurrence of HCC after MWA remain major concerns. Here, after reviewing the current therapeutic options for HCC, we focus on MWA, describing the advantages and challenges of MWA and the clinical results after treatment. We then focused on prognostic factors that influence post-ablation clinical outcomes and briefly presented the strategy of MWA for future clinical treatment.

Microwave ablation versus surgical resection for subcapsular hepatocellular carcinoma: a propensity score-matched study of long-term therapeutic outcomes

OBJECTIVES

The therapeutic efficacy of microwave ablation (MWA) for subcapsular hepatocellular carcinoma (HCC) has not been well characterized. We aimed to compare the long-term outcomes of MWA and surgical resection (SR) in patients with subcapsular HCC.

METHODS

This retrospective study comprised 321 patients with subcapsular HCC meeting the Milan criteria who received MWA (n = 99) or SR (n = 222). Local tumor progression (LTP), overall survival (OS), and disease-free survival (DFS) were analyzed using propensity score matching (PSM) to compare the therapeutic efficacy.

RESULTS

In the total cohort, there were no significant differences in 5-year LTP rates (14.0% vs. 8.9%, p = 0.12), OS rates (70.7% vs. 73.2%, p = 0.63), and DFS rates (38.3% vs. 41.2%, p = 0.22) between the MWA and SR groups. After PSM, the cumulative LTP rates at 1, 3, and 5 years were 9.7%, 14.0%, and 16.4% in the MWA group (n = 84) and 7.2%, 8.6%, and 10.6% in the SR group (n = 84), respectively, with no significant difference (p = 0.31). Neither corresponding OS rates (96.4%, 84.8%, and 73.0% vs. 95.2%, 85.5%, and 72.1%, p = 0.89) nor DFS rates (76.0%, 52.6%, and 38.1% vs. 76.2%, 44.7%, and 32.3%, p = 0.43) were significantly different between the MWA and SR groups. Whereas MWA obtained fewer complications for both cohorts (both p < 0.05).

CONCLUSION

MWA showed comparable long-term therapeutic outcomes to SR, and it might be an alternative curative option for subcapsular HCC within the Milan criteria.

KEY POINTS

• Microwave ablation showed comparable local tumor progression, overall survival, and disease-free survival to surgical resection for subcapsular hepatocellular carcinoma meeting the Milan criteria. • Microwave ablation obtained fewer complications and shorter postoperative hospital stay.

Study Protocol COVER-ALL: Clinical Impact of a Volumetric Image Method for Confirming Tumour Coverage with Ablation on Patients with Malignant Liver Lesions

PURPOSE

This study aims to evaluate the intra-procedural use of a novel ablation confirmation (AC) method, consisting of biomechanical deformable image registration incorporating AI-based auto-segmentation, and its impact on tumor coverage by quantitative three-dimensional minimal ablative margin (MAM) CT-generated assessment.

MATERIALS AND METHODS

This single-center, randomized, phase II, intent-to-treat trial is enrolling 100 subjects with primary and secondary liver tumors (≤ 3 tumors, 1-5 cm in diameter) undergoing microwave or radiofrequency ablation with a goal of achieving ≥ 5 mm MAM. For the experimental arm, the proposed novel AC method is utilized for ablation applicator(s) placement verification and MAM assessment. For the control arm, the same variables are assessed by visual inspection and anatomical landmarks-based quantitative measurements aided by co-registration of pre- and post-ablation contrast-enhanced CT images. The primary objective is to evaluate the impact of the proposed AC method on the MAM. Secondary objectives are 2-year LTP-free survival, complication rates, quality of life, liver function, other oncological outcomes, and impact of AC method on procedure workflow.

DISCUSSION

The COVER-ALL trial will provide information on the role of a biomechanical deformable image registration-based ablation confirmation method incorporating AI-based auto-segmentation for improving MAM, which might translate in improvements of liver ablation efficacy.

CONCLUSION

The COVER-ALL trial aims to provide information on the role of a novel intra-procedural AC method for improving MAM, which might translate in improvements of liver ablation efficacy.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04083378.

Percutaneous ultrasound-guided microwave ablation for treatment of hepatocellular carcinomas in dogs: four cases (2019-2020)

OBJECTIVES

To describe ultrasound-guided microwave ablation as a minimally invasive treatment option for primary or metastatic hepatocellular carcinomas.

METHODS

Four client-owned dogs underwent percutaneous ultrasound-guided microwave ablation of three primary and one metastatic hepatocellular carcinoma, diagnosed on cytology/histopathology. In each case, multiple ultrasound-guided thermal lesions were created in a 10 to 40 minutes ablation at 30 to 35 W. Real-time monitoring was performed using 10 MHz diagnostic ultrasound transducers. The procedures were performed without complication and CT scans or abdominal ultrasounds were repeated immediately after. Patients were discharged on oral analgesia on the same day or 24 hours later.

RESULTS

Hepatocellular carcinomas were successfully ablated, which in some cases resulted in an improvement in clinical signs and laboratory values. The patients were followed up for a time ranging between 39 and 649 days and no evidence of disease progression was found. Three out of four patients are still alive at the time of writing.

CLINICAL SIGNIFICANCE

In these four patients, minimally invasive ultrasound-guided microwave ablation was feasible and resulted in no immediate complications. Regular imaging follow-up is recommended after the procedure and further studies on microwave ablation are warranted to establish its effectiveness in dogs with hepatocellular carcinomas.

Thermochromic Tissue-Mimicking Phantoms for Thermal Ablation Based on Polyacrylamide Gel

In recent years, thermal ablation has played an increasingly important role in treating various tumors in the clinic. A practical thermochromic phantom model can provide a favorable platform for clinical thermotherapy training of young physicians or calibration and optimization of thermal devices without risk to animals or human participants. To date, many tissue-mimicking thermal phantoms have been developed and are well liked, especially the polyacrylamide gel (PAG)-based phantoms. This review summarizes the PAG-based phantoms in the field of thermotherapy, details their advantages and disadvantages and provides a direction for further optimization. The relevant physical parameters (such as electrical, acoustic, and thermal properties) of these phantoms are also presented in this review, which can assist operators in a deeper understanding of these phantoms and selection of the proper recipes for phantom fabrication.

The second Mexican consensus on hepatocellular carcinoma. Part II: Treatment

Hepatocellular carcinoma (HCC) is more frequently manifesting as one of the main complications of cirrhosis of the liver, its principal risk factor. There have been modifications in its incidence over the past decade, related to an epidemiologic transition in the etiology of cirrhosis, with a decrease in the prevalence of hepatitis C and an increase in nonalcoholic fatty liver disease (NAFLD) as a cause, as well as the development of HCC in the non-cirrhotic liver due to NAFLD. Genetic markers associated with the disease have been identified, and surveillance and diagnosis have improved. Regarding treatment, surgical techniques, in both resection and transplantation, have advanced and radiologic techniques, at the curative stage of the disease, have enhanced survival in those patients. And finally, there have been radical changes in the systemic approach, with much more optimistic expectations, when compared with the options available a decade ago. Therefore, the Asociación Mexicana de Hepatología decided to carry out the Second Mexican Consensus on Hepatocellular Carcinoma, which is an updated review of the available national and international evidence on the epidemiology, risk factors, surveillance, diagnosis, and treatment of the disease, to offer the Mexican physician current information on the different topics regarding hepatocellular carcinoma. In this second part of the document, the topics related to the treatment of HCC are presented.

The Increasing Role of CT-Guided Cryoablation for the Treatment of Liver Cancer: A Single-Center Report

Purpose: Cryoablation (CrA) is a minimally invasive treatment that can be used in primary and metastatic liver cancer. The purpose of this study was to assess the effectiveness of CrA in patients with hepatocellular carcinoma (HCC) and liver metastases. Methods: We retrospectively evaluated the patients who had CrA for HCC or liver metastases between 2015 and 2020. Technical success, complete ablation, CrA-related complications, local tumor progression, local recurrences, and distant metastases were evaluated in the study population. In patients with HCC, the median survival was also estimated. Results: Sixty-four liver tumors in 49 patients were treated with CrA (50 metastases and 14 HCC). The mean tumor diameter was 2.15 cm. The mean follow-up was 19.8 months. Technical success was achieved in the whole study population. Complete tumor ablation was observed after one month in 92% of lesions treated with CrA (79% and 96% in the HCC Group and metastases Group, respectively, p < 0.001). Local tumor progression occurred in 12.5 of lesions, with no difference between the study groups (p = 0.105). Sixteen patients (33%) developed local recurrence (45% and 29% in the HCC Group and metastases Group, respectively, p = 0.477). Seven patients (14%) developed distant metastases in the follow-up period. Ten patients (20.8%) underwent redo CrA for local recurrence or incomplete tumor ablation. Minor complications were observed in 14% of patients. In patients with HCC, the median survival was 22 months. Conclusions: CrA can be safely used for treatment of HCC and liver metastases not amenable of surgical resection. Further studies are necessary to better define the role of CrA in the multidisciplinary treatment of liver malignancies.

Effect of Severity of Liver Cirrhosis on Surgical Outcomes of Hepatocellular Carcinoma After Liver Resection and Microwave Coagulation

BACKGROUND

Liver resection (LR) and percutaneous microwave coagulation therapy (PMCT) are both considered as radical treatments for small hepatocellular carcinoma (HCC). However, it is still unclear whether to select LR or PMCT in HCC patients with different degrees of liver cirrhosis. The purpose of this study was to compare the efficacy of LR and PMCT in the treatment of solitary and small HCC accompanied with different degrees of liver cirrhosis.

METHODS

In this study, 230 patients with solitary HCC lesions ≤ 3 cm and Child-Pugh A liver function were retrospectively reviewed. Among these patients, 122 patients underwent LR, and 108 received PMCT. The short- and long-term outcomes were compared between these two procedures. Severity of liver cirrhosis was evaluated by using clinical scoring system (CSS) as previously published. Subgroup analysis based on CSS was performed to evaluate the effect of severity of liver cirrhosis on surgical outcomes after LR and PMCT.

RESULTS

There was no mortality within 90 days in both groups. Major complications were significantly more frequent in the LR group than in the PMCT group (18.8% vs. 4.6%, p<0.001). However, LR provided better surgical outcomes than PMCT. The 5-year overall survival (OS) rates for the LR and PMCT groups were 65.2% and 42%, respectively (p=0.006), and the corresponding disease-free survival (DFS) rates were 51.7% and 31.5%, respectively (p=0.004). Nevertheless, subgroup analysis showed that PMCT provided long-term outcomes that were similar to LR and lower surgical complications in HCC patients with CSS score≥4.

CONCLUSIONS

LR may provide better OS and DFS rates than PMCT for patients with solitary HCC lesions ≤ 3 cm and Child-Pugh A liver function irrespective of liver cirrhosis. PMCT should be viewed as the optimal treatment for solitary and small HCC with severe cirrhosis.

Microwave ablation shows similar survival outcomes compared with surgical resection for hepatocellular carcinoma between 3 and 5 cm

BACKGROUND

Microwave ablation (MWA) is a safe and effective locoregional ablation modality, but it is not clear whether the curative effect of MWA as to hepatocellular carcinoma (HCC) is comparable to that of surgical resection (SR). We aimed to compare the outcomes of MWA and SR for patients with HCC ranging from 3 to 5 cm.

METHODS

197 patients treated for HCC between 3 and 5 cm by MWA or SR were included from 2010 to 2017. Overall survival (OS), progression-free survival (PFS), complication and hospital stay of those patients were compared by using propensity score matching. The registration number of this clinical trial was ChiCTR2000033983.

RESULTS

For patients with HCC between 3 and 5 cm, the 1-, 3-, and 5- years OS rates were 90.3%, 79.7%, and 65.5% in the MWA group, and 96.7%, 88.6%, and 71%% in the SR group, respectively (p = 0.457). The 1-, 3- and 5- years PFS rates were 63.6%, 36.8% and 32.7% in the MWA group, and 74.2%, 41.9% and 35.5% in the SR group, respectively (p = 0.397). The MWA group showed fewer complications (55% versus 78.8%, p = 0.041) and shorter hospital stays (8 versus 15 days, p < 0.001) compared with the SR group.

CONCLUSION

MWA showed similar survival outcomes compared with SR for HCCs ranging from 3 to 5 cm. However, it showed favorable results in terms of hospital stay and complication rate compared to SR.

Hepatobiliary Cancers, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

The NCCN Guidelines for Hepatobiliary Cancers focus on the screening, diagnosis, staging, treatment, and management of hepatocellular carcinoma (HCC), gallbladder cancer, and cancer of the bile ducts (intrahepatic and extrahepatic cholangiocarcinoma). Due to the multiple modalities that can be used to treat the disease and the complications that can arise from comorbid liver dysfunction, a multidisciplinary evaluation is essential for determining an optimal treatment strategy. A multidisciplinary team should include hepatologists, diagnostic radiologists, interventional radiologists, surgeons, medical oncologists, and pathologists with hepatobiliary cancer expertise. In addition to surgery, transplant, and intra-arterial therapies, there have been great advances in the systemic treatment of HCC. Until recently, sorafenib was the only systemic therapy option for patients with advanced HCC. In 2020, the combination of atezolizumab and bevacizumab became the first regimen to show superior survival to sorafenib, gaining it FDA approval as a new frontline standard regimen for unresectable or metastatic HCC. This article discusses the NCCN Guidelines recommendations for HCC.

Percutaneous microwave ablation applications for liver tumors: recommendations for COVID-19 patients

Microwave ablation (MWA) is an alternative locoregional therapy to surgical resection of solid tumors in the treatment of malignancies, and is widely used for hepatic tumors. It has a slightly higher overall survival (OS) rate compared to external beam radiation therapy (EBRT), and proton beam therapy (PBT), and better long-term recurrence-free OS rate compared to radiofrequency ablation (RFA). In this paper, current commercial devices, most recent noncommercial designs, and the principles behind them alongside the recently reported developments and issues of MWA are reviewed. The paper also provides microscopic insights on effects of microwave irradiation in the body. Our review shows that MWA is a safe and effective, minimally invasive method with high ablation completion rates. However, for large tumors, the completion rates slightly decrease, and recurrences increase. Thus, for large tumors we suggest using a cooled shaft antenna or multiple antenna placements. Comparisons of the two common ablation frequencies 915 MHz and 2.45 GHz have shown inconsistent results due to non-identical conditions. This review suggests that 915 MHz devices are more effective for ablating large tumors and the theory behind MWA effects corroborates this proposition. However, for small tumors or tumors adjacent to vital organs, 2.45 GHz is suggested due to its more localized ablation zone. Among the antenna designs, the double-slot antenna with a metallic choke seems to be more effective by localizing the radiation around the tip of the antenna, while also preventing backward radiation towards the skin. The review also pertains to the use of MWA in COVID-19 patients and risk factors associated with the disease. MWA should be considered for COVID-19 patients with hepatic tumors as a fast treatment with a short recovery time. As liver injury is also a risk due to COVID-19, it is recommended to apply liver function tests to monitor abnormal levels in alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, and other liver function indicators.

A novel mono-modality fusion imaging method based on three-dimensional contrast-enhanced ultrasound for the evaluation of ablation margins after microwave ablation of hepatocellular carcinoma

Background

To investigate the feasibility and accuracy of using preoperative and postoperative three-dimensional contrast-enhanced ultrasound (3D CEUS) fusion imaging in the evaluation of safety margins after thermal ablation of hepatocellular carcinoma (HCC).

Methods

A total of the 24 patients with HCC who underwent microwave ablation (MWA) between June 2020 and December 2020 were enrolled in this study. All patients received preoperative and postoperative 3D CEUS. The preoperative and postoperative 3D CEUS images were then fused. The success rate and evaluation time were recorded. The ablation margin and whether or not the safety margin was reached were calculated and recorded. If the ablation safety margin was not reached, the residual ablation volume needed to cover the safety margin was calculated automatically. The agreement between contrast-enhanced computed tomography(CECT) and 3D CEUS fusion imaging in the evaluation of ablation margins was explored using the kappa coefficient.

Results

The 3D CEUS fusion success rate was 95.8% (23/24), with a mean fusion time of (4.1±1.8) minutes. Twenty-three tumors were completely ablated, and the safety margin was achieved for 9 tumors. The ablation margin of 14 tumors was <5 mm. The mean uncovered safety margin volume was (2.27±2.11) mL, and the mean proportion of the uncovered safety margin to the whole safety margin was 16.8%. According to the results of preoperative and postoperative CECT fusion imaging, the ablation margin of 13 tumors was <5 mm, and the ablation margin of 10 tumors was >5 mm. The 2 methods showed excellent consistency, with a Kappa value of 0.911 (P=0.000012).

Conclusions

This study has presented a novel mono-modality fusion imaging method based on CEUS. We demonstrated that 3D CEUS fusion has a short fusion time and a high success rate, as well as good consistency with enhanced CT fusion. Therefore, 3D CEUS fusion is a feasible and accurate tool for evaluating the immediate efficacy of thermal ablation of HCC.

CT-based quantification of short-term tissue shrinkage following hepatic microwave ablation in an in vivo porcine liver model

BACKGROUND

Microwave ablation (MWA) is a minimally invasive treatment option for solid tumors and belongs to the local ablative therapeutic techniques, based on thermal tissue coagulation. So far there are mainly ex vivo studies that describe tissue shrinkage during MWA.

PURPOSE

To characterize short-term volume changes of the ablated zone following hepatic MWA in an in vivo porcine liver model using contrast-enhanced computer tomography (CECT).

MATERIAL AND METHODS

We performed multiple hepatic MWA with constant energy parameters in healthy, narcotized and laparotomized domestic pigs. The volumes of the ablated areas were calculated from venous phase CT scans, immediately after the ablation and in short-term courses of up to 2 h after MWA.

RESULTS

In total, 19 thermally ablated areas in 10 porcine livers could be analyzed (n = 6 with two volume measurements during the measurement period and n = 13 with three measurements). Both groups showed a statistically significant but heterogeneous volume reduction of up to 12% (median 6%) of the ablated zones in CECT scans during the measurement period (P < 0.001 [n = 13] and P = 0.042 [n = 6]). However, the dimension and dynamics of volume changes were heterogenous both absolutely and relatively.

CONCLUSION

We observed a significant short-term volume reduction of ablated liver tissue in vivo. This volume shrinkage must be considered in clinical practice for technically successful tumor treatment by MWA and therefore it should be further investigated in in vivo studies.

Liver tumor ablation in difficult locations: Microwave ablation of perivascular and subdiaphragmatic hepatocellular carcinoma

AIM

To assess the safety and efficacy of CT-guided microwave ablation (MWA) of hepatocellular carcinoma (HCC) near large blood vessels and the diaphragm by analyzing procedural complications and local tumor progression (LTP).

METHODS

From October 2013 through January 2019, 80 patients (54 males and 26 females) with 136 tumors who underwent CT-guided MWA of HCC were included in this retrospective analysis. MWA was performed on 43 perivascular HCC (≤5 mm from a vessel measuring ≥5 mm in diameter), 38 subdiaphragmatic HCC (≤5 mm from diaphragm), and 64 control HCC. Risk factors for local tumor progression (LTP), overall survival, and complications were analyzed using the Chi-square and Cox proportional hazards model methods.

RESULTS

The technical success rate of MWA was 100%. Complication incidence was not significantly different between perivascular and control tumors (20.9% vs 10.9%; p = 0.155) or between subdiaphragmatic and control tumors (21.1% vs 10.9%; p = 0.163). The effect of lesion location on LTP disappeared while controlling for age and lesion size. There was no significant difference in median survival time between patients who had only control tumors (38.8 months) compared to patients with at least one perivascular or subdiaphragmatic tumor (42.5 months; p = 0.098).

CONCLUSION

CT-guided percutaneous MWA of perivascular and subdiaphragmatic HCC tumors is safe and effective. The local tumor recurrence and survival was not significantly different compared to control tumors.

Interleukin 22 is related to development and poor prognosis of hepatocellular carcinoma

BACKGROUND AND AIMS

Immune response against hepatitis B virus (HBV) infection is an important risk factor for the development of hepatocellular carcinoma (HCC). Studies have reported that interleukin 22 (IL-22) exhibits both protective and pathological properties in liver diseases. Our aim was to explore the importance of IL-22 in the development of HCC, and to characterize the relationship between IL-22 levels and the prognosis of HCC.

METHODS

Totally, 136 liver biopsy specimens from 46 patients with chronic hepatitis B (CHB), 37 with atypical hyperplasia (AH), 53 with HCC, patient-matched tumors and peritumoral surgical specimens from 56 HCC patients included in the study. The expression of IL-22 and CD8 was evaluated by immunochemistry. Corresponding serum samples were collected from 30 CHB, 30 AH, and 30 HCC patients. IL-22 expression was determined by an enzyme linked immunosorbent assay.

RESULTS

Liver-infiltrating IL-22+ cells increased in a stepwise manner from CHB to AH and HCC (CHB vs. AH, P=0.002; AH vs. HCC, P=0.010), whereas a decreasing trend was observed for CD8+ T cells (CHB vs. AH, P=0.031; AH vs. HCC, P=0.652). Serum IL-22 levels also increased from CHB to AH and HCC (CHB vs. AH, P=0.024; AH vs. HCC, P=0.026). Tumor-infiltrating IL-22+ cells and serum IL-22 were associated with histologic grade (P=0.024 and P=0.033). Additionally, CD8+ T cells correlated with tumor size (P=0.032). Furthermore, the high intratumoral IL-22+ cell group and high serum IL-22 group showed lower overall survival (OS; P=0.001, P=0.017) and disease-free survival (DFS; P=0.005, P<0.001). Multivariate analysis revealed that intratumoral IL-22+ cells and serum IL-22 levels were independent prognostic factors for both OS and DFS.

CONCLUSIONS

These findings indicate that IL-22 promotes the progression of HCC in CHB patients. High tumor-infiltrating IL-22+ cells and serum IL-22 levels are thought to be unfavorable prognostic indicators for HCC.

Radiofrequency ablation versus microwave ablation for early stage hepatocellular carcinoma: A PRISMA-compliant systematic review and meta-analysis

BACKGROUND

Several randomized control trials (RCTs) were conducted to compare microwave ablation (MWA) and radiofrequency ablation (RFA) in the treatment of hepatocellular carcinoma (HCC) over the years. The purpose of this study was to compare the efficacy of RFA and MWA for early stage HCC.

METHODS

Studies were systematically searched on Emabse, Ovid Medline, PubMed, and Cochrane Library until March 20, 2020. Continuous variables and dichotomous variables were compared using weighted mean difference (WMD) and odds ratio (OR), respectively. For the comparison of overall survival (OS) and disease-free survival (DFS), the hazard ratio (HR) and 95% confidence interval (CI) were extracted from univariate analysis or survival plots.

RESULTS

A total of 26 studies (5 RCTs and 21 cohorts) with 4396 patients (2393 patients in RFA and 2003 patients in MWA) were included in our study. Of these patients, 47% received treatment under general anesthesia in the MWA group and 84% in the RFA group (OR = 0.529, P < .001). The median ablation time was reduced in the MWA group (12 minutes) compared with RFA group (29 minutes) (WMD = -15.674, P < .001). In total, 17.6% patients exhibited progression during follow-up in the MWA group compared with 19.5% in the RFA group (OR = 0.877, P = .225). No statistically significant differences were observed between MWA and RFA groups in terms of OS and DFS (HR = 0.891 and 1.014, P = .222 and .852, respectively).

CONCLUSIONS

MWA exhibited similar therapeutic effects as RFA in the treatment of early stage HCC. Given the shorter ablation time, MWA can be performed under local anesthesia.

The Learning Curve for Thermal Ablation of Liver Cancers: 4,363-Session Experience for a Single Central in 18 Years

This study aimed to explore the special efforts required to achieve proficiency in performing thermal ablation of liver cancers, including tumors in difficult locations, and clarify the effects of handing-down teaching on the corresponding process. Major complications of patients receiving percutaneous thermal ablation of liver cancer were analyzed. Polynomial fitting was used to describe the connection between major complication rates and special experience. Learning curve of major complications was plotted both for the whole group and for each operator, respectively. Tumors in difficult locations were further studied. A total of 4,363 thermal ablation sessions were included in this study. 143 of 4,363 patients had major complications, corresponding to an incidence rate of 3.27%. 806 thermal ablation sessions were performed for tumors in difficult locations. The major complication rate of these sessions is 6.33%. According to the trend of the learning curve of the 4363 patients, the experience of the whole group can be classified into five stages, that is, the high-risk, relatively stable, unstable, proficient and stable periods. A learning curve for an individual operator can be classified into the high-risk, proficient and stable periods. The major complication rates for the chronologically first, second and third operator of the group are 3.23, 3.35, and 3.31%, respectively. The special experience needed to bypass the first stage corresponds to 410, 510, and 440 sessions, the second stage, 1850, 850, and 870 sessions, by the three operators, respectively. The major complication rates for the tumors in difficult locations for the first, second and third operator were 7.04, 5.53, and 5.98%, respectively. For the tumors in difficult locations, the special experience needed to bypass the first stage corresponds to 150, 130, and 140 sessions, the second stage, 290, 175, and 185 sessions, by the three operators, respectively. In conclusion, the learning process of an operator percutaneous thermal ablation for liver cancer can be classified into three stages. The major complication rate for tumors in difficult locations were higher than that for all tumors. Handing-down teaching can make an operator arrive at the third stage earlier but not the second stage.

Survival analysis following microwave ablation or surgical resection in patients with hepatocellular carcinoma conforming to the Milan criteria

The aim of the present study was to compare the efficacy of microwave ablation (MWA) and surgical resection (RES) for the treatment of hepatocellular carcinoma (HCC) conforming to the Milan criteria and the associated short- and long-term survival rates. The baseline characteristics were obtained from 231 patients with HCC who met the Milan criteria. To compare the mortality rates between groups, survival analysis was conducted using the Kaplan-Meier method and the log-rank test. The factors associated with the survival rate were analyzed using Cox proportional hazard models. A total of 115 patients underwent RES, and 116 were treated with MWA. No significant differences were observed in the 1-, 3- and 5-year OS rates and the 1-year DFS rate between the two groups. The 7- and 10-year OS rates and the 3-, 5-, 7- and 10-year DFS rates of the RES group were significantly higher compared with those in the MWA group (P=0.004, P=0.002, P=0.003 and P=0.002, respectively). In addition, no marked differences were observed in the OS and DFS rates between the two groups of patients with solitary HCC lesions ≤3 cm (P=0.066 and P=0.056) and in the OS of those with solitary lesions of 3-5 cm (P=0.133); however the DFS of patients with single 3-5 cm HCC lesions in the RES group was notably higher compared with the MWA group (P=0.027). The Cox proportional hazard model revealed that age, hepatitis B and C virus infection, tumor size, number, platelet count and the type of treatment intervention were risk factors affecting the survival and recurrence in patients with HCC. These results suggested that RES may provide superior survival benefits compared with MWA for patients with HCC who meet the Milan criteria.

Adjuvant Thermal Accelerant Gel Use Increases Microwave Ablation Zone Temperature in Porcine Liver as Measured by MR Thermometry

PURPOSE

To determine the effects of a thermal accelerant gel on temperature parameters during microwave liver ablation.

MATERIALS AND METHODS

Sixteen consecutive liver ablations were performed in 5 domestic swine under general anesthesia with (n = 8) and without (n = 8) administration of thermal accelerant gel. Ablation zone temperature was assessed by real-time MR thermometry, measured as maximum temperature (T_max) and the volume of tissue ≥ 60°C (V₆₀). Tissue heating rate, ablation zone shape, and thermal energy deposition using the temperature degree-minutes at 43°C (TDM43) index were also measured. Differences between groups were analyzed using generalized mixed modeling with significance set at P = .05.

RESULTS

Mean peak ablation zone temperature was significantly greater with thermal accelerant use (mean T_max, thermal accelerant: 120.0°C, 95% confidence interval [CI] 113.0°C-126.9°C; mean T_max, control: 80.3°C, 95% CI 72.7°C-88.0°C; P < .001), and a significantly larger volume of liver tissue achieved or exceeded 60°C when thermal accelerant was administered (mean V₆₀, thermal accelerant: 22.2 cm³; mean V₆₀, control: 15.9 cm³; P < .001). Significantly greater thermal energy deposition was observed during ablations performed with accelerant (mean TDM43, thermal accelerant: 198.4 min, 95% CI 170.7-230.6 min; mean TDM43, control: 82.8 min, 95% CI 80.5-85.1 min; P < .0001). The rate of tissue heating was significantly greater with thermal accelerant use (thermal accelerant: 5.8 min ± 0.4; control: 10.0 min; P < .001), and accelerant gel ablations demonstrated a more spherical temperature distribution (P = .002).

CONCLUSIONS

Thermal accelerant use is associated with higher microwave ablation zone temperatures, greater thermal energy deposition, and faster and more spherical tissue heating compared with control ablations.

The efficacy of microwave ablation versus liver resection in the treatment of hepatocellular carcinoma and liver metastases: A systematic review and meta-analysis

BACKGROUND

Microwave ablation (MWA) is an important method in the treatment of liver cancer. This systematic review compared MWA with liver resection (LR) for liver cancer treatment. In recent years, the MWA has been also reported to play an important role. Studies comparing MWA and LR are lacking. This study aims to compare the efficacy of MWA and LR in the treatment of hepatocellular carcinoma (HCC).

METHODS

A systematic search of PubMed, Embase, Cochrane Library and Web of Science up to April 1, 2019 was conducted for relevant studies that compared the efficacy of MWA and LR in the treatment of HCC. The primary outcomes were local tumor recurrence (LTR) and overall survival (OS) of patients. The secondary outcomes included disease free survival (DFS), extrahepatic metastasis, intrahepatic de novo lesions, length of stay, complications, intraoperative blood loss and operative time.

RESULTS

A total of 16 studies including 2622 patients were identified. Incidence of LTR was significantly higher in patients with MWA than LR, with a pooled OR of 2.69 (95% CI 1.33-5.41; P = 0.006). No significant difference in 1-year OS was found. However, patients with MWA experienced higher 3- and 5-year OS, with pooled ORs of 1.40 (95% CI 1.07-1.84; P = 0.01) and 1.41 (95% CI 1.10-1.80; P = 0.007) respectively. In secondary measures, the 1- and 3-year DFS were significantly higher in patients with MWA. However, no significant difference of 5-year DFS was observed. In addition, lower incidence of complications, less intraoperative blood loss and shorter operative time and shorter length of stay were observed in MWA.

CONCLUSIONS

Though MWA may lead to higher incidence of recurrence, it may be an effective and safe alternative in patients with HCC or liver metastases. MWA may have benefits in patients' survival and safety. Randomized studies should be performed to determine the target population that benefits most from MWA in the future.

A review of conventional and newer generation microwave ablation systems for hepatocellular carcinoma

Although microwave ablation (MWA) exhibits a high thermal efficiency, the major limitation of conventional MWA systems is the lack of predictability of the ablation zone size and shape. Therefore, a specific newer generation MWA system, The Emprint™ Ablation System with Thermosphere™ Technology, was designed to create predictable large spherical zones of ablation that are not impacted by varying tissue environments. The time required for ablation with MWA systems is short, and the shape of the necrosis is elliptical with the older systems and spherical with the new system. In addition, because MWA has no heat-sink effect, it can be used to ablate tumors adjacent to major vessels. Although these factors yield a large ablation volume and result in good local control, excessive ablation of liver tissue and unexpected ablation of surrounding organs are possible. Therefore, MWA should be carefully performed. This review highlights the efficacy and complications of MWA performed with conventional systems and the newer generation system in patients with hepatocellular carcinoma (HCC). MWA with the newer generation system seems to be a promising treatment option for large HCCs and secondary hepatic malignancies, with several advantages over other available ablation techniques, including conventional MWA. However, further randomized controlled trials are necessary to fully clarify the benefits and pitfalls of this new system.

Locoregional Therapy, Immunotherapy and the Combination in Hepatocellular Carcinoma: Future Directions

Image-guided locoregional therapies (LRTs) have long been a vital part of treatment regimens for hepatocellular carcinoma (HCC). Ablation, chemoembolization, and radioembolization are examples of commonly used treatment techniques for HCC. This review describes the various methods utilized to treat HCC in the field of interventional oncology and also focuses on new and novel treatment concepts being developed in the field including the use of novel immunotherapy agents and combination therapy of LRTs with immunotherapy.

Hepatic resection versus operative microwave ablation for single hepatocellular carcinoma ≤5 cm: A propensity score-matched analysis

BACKGROUND

Little evidence exists regarding the perioperative and oncologic benefits of microwave ablation for hepatocellular carcinoma. The aim of this study was to compare the efficacy of hepatic resection and operative microwave ablation (microwave coagulo-necrotic therapy) for single hepatocellular carcinoma ≤5 cm.

METHODS

Between 1994 and 2015, a total of 551 patients with a single hepatocellular carcinoma ≤5 cm were treated in our institution (hepatic resection: n = 128; microwave coagulo-necrotic therapy: n = 423). We compared overall survival and recurrence-free survival between hepatic resection and microwave coagulo-necrotic therapy. Propensity score matching analysis identified 94 matched pairs of patients to compare outcomes.

RESULTS

After propensity score matching, baseline variables, including liver function and tumor size, were well-balanced between the 2 groups. The 5- and 10-year overall survival rates were 76% and 47% for hepatic resection and 77% and 48% for microwave coagulo-necrotic therapy, respectively (P = .865). The 5- and 10-year recurrence-free survival rates were 55% and 41% for hepatic resection and 47% and 32% for microwave coagulo-necrotic therapy, respectively (P = .377). In the subgroup analysis, the hepatic resection group had better recurrence-free survival than the microwave coagulo-necrotic therapy group in patients with tumor size >3 cm, with 5-year recurrence-free survival rates of 56.5% and 32.4% in the hepatic resection and microwave coagulo-necrotic therapy group, respectively (P = .029).

CONCLUSION

Our propensity score matching study confirmed no statistically significant differences in both overall survival and recurrence-free survival between hepatic resection and microwave coagulo-necrotic therapy for single hepatocellular carcinoma ≤5 cm; however, hepatic resection is recommended for hepatocellular carcinoma with tumor size >3 cm when patients have good liver function.

Microwave ablation compared with hepatic resection for the treatment of hepatocellular carcinoma and liver metastases: a systematic review and meta-analysis

Background

Hepatic resection (HR) is the gold standard liver cancer treatment, but few patients are eligible due to comorbidities or tumor location. Microwave ablation (MWA) is an important complementary liver cancer treatment to HR. This systematic review compared MWA with HR for liver cancer treatment.

Methods

A systematic search of MEDLINE, EMBASE, and CENTRAL was conducted for randomized and observational studies published from 2006 onwards. The primary outcome was local tumor recurrence (LTR), and a random effects model was used for meta-analyses.

Results

Of the 1845 studies identified, 1 randomized and 15 observational studies met the inclusion criteria. LTR was significantly increased with MWA versus HR (risk ratio (RR) = 2.49; P = 0.016). In secondary measures, HR provided significantly higher 3- and 5-year overall survival (RR = 0.94; P = 0.03 and RR = 0.88; P = 0.01, respectively) and 3-year disease-free survival (RR = 0.78; P = 0.009). MWA exhibited significantly shorter length of stay (weighted mean difference (WMD) = − 6.16 days; P < 0.001) and operative time (WMD = − 58.69 min; P < 0.001), less intraoperative blood loss (WMD = − 189.09 mL; P = 0.006), and fewer complications than HR (RR = 0.31; P < 0.001). When MWA was combined with HR and compared with either modality alone, complications and blood loss were significantly lower with the combination treatment; however, there were no differences in other outcomes. Subgroup and sensitivity analyses were generally aligned with the main results.

Conclusions

MWA can be an effective and safe alternative to HR in patients/tumors that are not amenable to resection. More randomized and economic studies should be performed that compare the two treatments, especially to determine the target population that benefits most from MWA.

Electronic supplementary material

The online version of this article (10.1186/s12957-019-1632-6) contains supplementary material, which is available to authorized users.

Evaluation of Probe Angles for Synchronous Waveform 915-MHz Microwave Ablation

BACKGROUND

The purpose of this study is to compare the ablation performance between a synchronous microwave ablation (MWA) system and a commercially available asynchronous system in ex vivo bovine liver and evaluate the efficacy of ablation at varying entrance angles.

MATERIALS AND METHODS

Two 915-MHz MWA systems were used in bench top ex vivo bovine livers with various conditions (synchronous versus asynchronous). Using synchronous technology ablations to liver, kidney, or lung at angles of 0, 15, 30, and 90° were evaluated.

RESULTS

Synchronous and asynchronous MWA systems created mean ablation zone volumes of 26.4 and 15.8 cm³, 62.9 and 45.4 cm³, 90.8 and 56.4, and 75.7 and 54.8 cm³ with single, double (2 microwave probes in use simultaneous) (2 cm spacing), and triple (three probes in use simultaneously) (2 cm and 3 cm spacing) antennae configurations, respectively; adjusted P-values ≤ 0.006. Ablation defects were similar across all groups when evaluated for entrance angle. Specifically, when comparing 0-degree angle to all other angles, achieved zones of ablation (ZA) were similar (mean ± standard deviation for 0-degree versus all other angles: 8.72 ± 4.84 versus 9.38 ± 4.11 cm², P = 0.75). The use of the long-tip probe resulted in a statistically significant increase in the achieved ZA when compared to the short tip probe (10.9 ± 4.3 versus 6.5 ± 2.4, respectively; P = 0.01).

CONCLUSIONS

Newly developed synchronous microwave technology creates significantly larger ablation zones when compared to an existing asynchronous commercially available system. The angle of approach does not affect the resulting ZA. This is clinically relevant as true 0-degree angle is often difficult to obtain.

Transarterial chemoembolization with radiofrequency ablation versus hepatectomy in hepatocellular carcinoma beyond the Milan criteria: a retrospective study

Purpose

To compare the efficacies of transarterial chemoembolization (TACE) combined with radiofrequency ablation (RFA) with hepatectomy. Prognostic factors for the patient groups were analyzed.

Patients and methods

Data of 314 newly diagnosed cases of hepatocellular carcinoma beyond the Milan criteria were studied from January 2012 to December 2013 in our hospital. Forty-four patients were excluded owing to loss to follow-up (27 cases) or missing imaging data (17 cases); finally, 270 patients were included. All patients underwent TACE combined with RFA (TR group, 136 patients) or hepatectomy (HT group, 134 patients). Efficacy evaluation and prognostic factor analysis of the groups were conducted. Overall survival (OS) rate, progression-free survival (PFS) rate, and major complications were recorded.

Results

The 1-, 2-, 3-, and 5-year OS rates and median survival times were 98.5%, 83.1%, 66.2%, 37.1%, and 46 months, respectively, for the TR group and 89.6%, 69.4%, 53.7%, 30.3%, and 38 months, respectively, for the HT group. There were significant statistical differences in survival rate and median survival time between the groups. Median PFS was 21 months for the TR group and 8 months for the HT group. Difference between groups was statistically significant. Multivariate analysis showed treatment method, tumor diameter and number, Child–Pugh classification, antiviral therapy, and alpha-fetoprotein levels were the independent factors affecting OS rates. Treatment mode and tumor diameter and number were the independent factors affecting PFS.

Conclusion

TACE with RFA is superior to hepatectomy in hepatocellular carcinoma treatment beyond the Milan criteria.

Comparative efficacy of treatment strategies for hepatocellular carcinoma: systematic review and network meta-analysis

OBJECTIVE

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death worldwide. We conducted network meta-regression within a Bayesian framework to compare and rank different treatment strategies for HCC through direct and indirect evidence from international studies.

METHODS AND ANALYSES

We pooled the OR for 1-year, 3-year and 5-year overall survival, based on lesions of size ˂ 3 cm, 3-5 cm and ≤5 cm, using five therapeutic options including resection (RES), radiofrequency ablation (RFA), microwave ablation (MWA), transcatheter arterial chemoembolisation (TACE) plus RFA (TR) and percutaneous ethanol injection (PEI).

RESULTS

We identified 74 studies, including 26 944 patients. After adjustment for study design, and in the full sample of studies, the treatments were ranked in order of greatest to least benefit as follows for 5 year survival: (1) RES, (2) TR, (3) RFA, (4) MWA and (5) PEI. The ranks were similar for 1- and 3-year survival, with RES and TR being the highest ranking treatments. In both smaller (<3 cm) and larger tumours (3-5 cm), RES and TR were also the two highest ranking treatments. There was little evidence of inconsistency between direct and indirect evidence.

CONCLUSION

The comparison of different treatment strategies for HCC indicated that RES is associated with longer survival. However, many of the between-treatment comparisons were not statistically significant and, for now, selection of strategies for treatment will depend on patient and disease characteristics. Additionally, much of the evidence was provided by non-randomised studies and knowledge gaps still exist. More head-to-head comparisons between both RES and TR, or other approaches, will be necessary to confirm these findings.

Percutaneous Microwave Ablation Under CT Guidance for Hepatocellular Carcinoma: a Single Institutional Experience

BACKGROUND

Microwave ablation (MWA) is an emerging treatment for treatment of patients with hepatocellular carcinoma (HCC) not amenable of surgical resection.

PATIENTS AND METHODS

We searched for patients diagnosed as having small-, medium-, and large HCCs treated with MWA under CT guidance between 2010 and 2014. The main outcomes of interest were rates of complete ablation, complications, and overall survival. Rates of complete ablation were compared with Chi-square test, and estimated survival rates were calculated by means of Kaplan-Meier method.

RESULTS

Thirty-two patients with 45 HCC nodules received MWA. Seventeen (37.8%) nodules were <3 cm (small), 15 (33.3%) between 3 and 5 cm (medium), and 13 (28.9%) > 5 cm (large). Complete ablation was obtained in 94.1% of small tumors, 80% of medium tumors, and 53.8% of large tumors (p = 0.03). Two patients had HCC located in risk area (paracardiac position). Minor complications occurred after seven procedures (15.5%). Estimated median survival was 37 months (95% confidence interval 11.97-62.02). One-year OS was 82.7%, 2-year survival 68.9%, and 3-year survival 55.2%.

CONCLUSION

MWA is a versatile ablative method that can be applied in HCC at various stages, and also in lesions located in risk areas.

Impact of local tumor lesion treatments and preoperative indicators on the survival of patients with small hepatocellular carcinomas

The prognosis for small hepatocellular carcinomas (SHCC) remains uncertain. The aim of the present study was to compare three local tumor lesion treatments and identify the prognostic factors in patients with SHCC by analyzing preoperative indicators. A retrospective study was performed using data from 206 patients with SHCC from 2006–2015. All of the patients had undergone transarterial chemoembolization (TACE) alone, TACE plus percutaneous microwave coagulation therapy (PMCT) or surgical resection (SR). The Kaplan-Meier method was used to calculate the survival rates. Multivariate analysis was conducted using Cox regression analysis. The median survival time of patients with SHCC was 27 (range, 14–49) months in the TACE group, 29.5 (range, 16–52) months in the TACE-PMCT group and 36.5 (range, 26–52) months in the SR group (P=0.091). The 1, 3 and 5-year survival rates for patients with SHCC were 82.4, 64.9 and 46.8% in the TACE group; 89.0, 72.6 and 58.3% in the TACE-PMCT group and 88.8, 72.3 and 58.6% in the SR group (P=0.181), respectively. Analysis from the Cox regression model demonstrated that preoperative α-fetoprotein (AFP; <400 ng/ml vs. ≥400 ng/ml; HR=0.548; P=0.036) was an independent predictor of the survival time of patients with SHCC. Analysis of patients with preoperative AFP levels of ≥400 ng/ml revealed that the median survival time in the SR group was 36 (range, 28.25–52) months, significantly longer than the TACE (17 months; range, 12–44 months) and TACE-PMCT group (27 months; range, 14–55 months; P=0.035). The 1, 2 and 3-year survival rates for patients with SHCC with ≥400 ng/ml AFP were: 70.8, 55.5 and 49.9% in the TACE group; 83.7, 68.0 and 60.8% in the TACE-PMCT group; and 90.9, 81.8 and 61.0% in SR group, respectively (P=0.664). However, there was no significant difference among the three groups in the survival time of patients with SHCC with <400 ng/ml preoperative AFP. The observations indicated that SR is not significantly different for overall survival time in the patients with SHCC between the two groups; this method can be employed for patients with SHCC. This was based on the median survival time of patients with ≥400 ng/ml AFP in the SR group who had a longer survival time and a higher survival rate than in the TACE and TACE-PMCT group.

No-touch multibipolar radiofrequency ablation vs. surgical resection for solitary hepatocellular carcinoma ranging from 2 to 5 cm

BACKGROUND & AIMS

No-touch multibipolar radiofrequency ablation (NTM-RFA) represents a novel therapy that surpasses standard RFA for hepatocellular carcinoma (HCC), but it has not been compared to surgical resection (SR). We aimed to compare the outcomes of NTM-RFA and SR for intermediate-sized HCC.

METHODS

Between 2012 and 2016, 141 patients with solitary HCC ranging from 2 to 5 cm were treated by NTM-RFA or SR at a single-center. The outcomes of 128 patients were compared after using inverse probability of treatment weighting (IPTW).

RESULTS

Seventy-nine patients had NTM-RFA and 62 had SR. After IPTW, the two groups were well-balanced for most baseline characteristics including tumor size, location, etiology, severity of underlying liver disease and alpha-fetoprotein level. Morbidity was higher (67.9% vs. 50.0%, p = 0.042) and hospital stay was longer (12 [IQR 8-13] vs. 7 [IQR 5-9] days, p <0.001) after SR. Local recurrence rates at one and three years were 5.5% and 10.0% after NTM-RFA and 1.9% and 1.9% after SR, respectively (p = 0.065). The rates of systematized recurrence (within the treated segment or in an adjacent segment within a 2 cm distance from treatment site) were higher after NTM-RFA (7.4% vs. 1.9% at one year, 27.8% vs. 3.3% at three years, p = 0.008). Most patients with recurrence were eligible for rescue treatment, resulting in similar overall survival (86.7% after NTM-RFA, 91.4% after SR at three years, p = 0.954) and disease-free survival (40.8% after NTM-RFA, 56.4% after SR at three years, p = 0.119).

CONCLUSION

Compared to SR, NTM-RFA for solitary intermediate-sized HCC was associated with less morbidity and more systematized recurrence, while the rate of local recurrence was not significantly different. Most patients with intrahepatic recurrence remained eligible for rescue therapies, resulting in equivalent long-term oncological results after both treatments.

LAY SUMMARY

Outcomes of patients treated for intermediate-sized hepatocellular carcinoma by surgical resection or no-touch multibipolar radiofrequency ablation were compared. No-touch multibipolar radiofrequency ablation was associated with a lower overall morbidity and a higher rate of systematized recurrence within the treated segment or in an adjacent segment within a 2 cm distance from the initial tumor site. Most patients with intrahepatic recurrence remained eligible for rescue curative therapy, enabling them to achieve similar long-term oncological results after both treatments.

Liver-Directed Therapies for Hepatocellular Carcinoma and Intrahepatic Cholangiocarcinoma

Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (IHC) are primary liver cancers where all or most of the tumor burden is usually confined to the liver. Therefore, locoregional liver-directed therapies can provide an opportunity to control intrahepatic disease with minimal systemic side effects. The English medical literature and clinical trials were reviewed to provide a synopsis on the available liver-directed percutaneous therapies for HCC and IHC. Locoregional liver-directed therapies provide survival benefit for patients with HCC and IHC compared to best medical treatment and have lower comorbid risks compared to surgical resection. These treatment options should be considered, especially in patients with unresectable disease.

The Performance of Higher Frequency Microwave Ablation in the Presence of Perfusion

OBJECTIVE

In this paper, we investigate the impact of perfusion on the performance of microwave ablation across a large frequency range.

METHODS

We designed multiple microwave ablation antennas to operate in liver tissue at discrete frequencies in the range 1.9-18 GHz. We performed electromagnetic simulations to calculate microwave power absorption patterns. Five-minute, 25 W ablation experiments were performed at each frequency in perfused and nonperfused ex vivo porcine livers, and thermal lesion dimensions were measured.

RESULTS

The volume of greatest microwave power absorption shrinks by two orders of magnitude as the frequency is increased from 1.9 to 18 GHz. Mean thermal lesion volumes are consistent across the frequency range for a given perfusion state and are about three times smaller under active perfusion. Typical thermal lesion diameters (perpendicular to the antenna axis) were 24 mm and 16 mm for nonperfused and perfused ablations, respectively. No significant differences in axial ratio were observed among different frequency groups in active-perfusion experiments.

CONCLUSION

Higher-frequency microwave ablation produces thermal lesions with volumes comparable to those achieved at lower frequencies, even in strongly perfused environments.

SIGNIFICANCE

Higher-frequency microwave ablation is appealing because it allows for more flexibility in antenna design. A critical issue concerning the feasibility of higher frequency microwave ablation, considering its strong dependence on heat diffusion to grow thermal lesions, is its performance in strongly perfused environments. This paper shows that higher frequency microwave ablation achieves thermal lesions comparable to those from microwave ablation performed at conventional frequencies in both non- and strongly perfused environments.

Utility of endoscopic ultrasound and endoscopy in diagnosis and management of hepatocellular carcinoma and its complications: What does endoscopic ultrasonography offer above and beyond conventional cross-sectional imaging?

Hepatocellular carcinoma constitutes over 90% of the primary liver tumors, the rest being cholangiocarcinoma. It has an insidious presentation, which is responsible for the delayed presentation. Hence, the management strategy relies on screening to diagnose it an early stage for curative resection and/or treatment with local ablative techniques or chemotherapy. However, even with different screening programs, more than 60% of tumors are still detected at an advanced stage, leading to an unchanged mortality rate, thereby implying a room for improvement in the screening and diagnostic process. In the last few years, there has been evolution of utility of endoscopy, specifically endoscopic ultrasonography along with Fine needle aspiration, for this purpose, which we comprehensively review in this article.

NCCN Guidelines Insights: Hepatobiliary Cancers, Version 1.2017

The NCCN Guidelines for Hepatobiliary Cancers provide treatment recommendations for cancers of the liver, gallbladder, and bile ducts. The NCCN Hepatobiliary Cancers Panel meets at least annually to review comments from reviewers within their institutions, examine relevant new data from publications and abstracts, and reevaluate and update their recommendations. These NCCN Guidelines Insights summarize the panel's discussion and most recent recommendations regarding locoregional therapy for treatment of patients with hepatocellular carcinoma.

Comparison of microwave ablation and hepatic resection for hepatocellular carcinoma: a meta-analysis

BACKGROUND AND AIMS

Hepatic resection (HRN) and microwave ablation (MWA) have significant advantages in treating hepatocellular carcinoma; however, it remains unclear which way produces better outcomes. This meta-analysis of cohort studies compared the treatments in terms of effectiveness and safety.

METHODS

Six electronic databases (PubMed, Medline, EMBASE, Web of Science, EBSCO, and The Cochrane Library) were retrieved for studies comparing MWA and HRN. The meta-analysis was conducted based on statement of preferred reporting items for systematic reviews and meta-analyses.

RESULTS

Nine studies met the inclusion criteria, with a total of 1,480 patients. The overall meta-analysis demonstrated no significant difference in overall survival between the MWA group and the HRN group (HR =0.98, 95% CI =0.76-1.26, P=0.878). There was no difference in disease-free survival between the MWA group and the HRN group (HR =1.16, 95% CI =0.79-1.71, P=0.442). Meanwhile, the meta-analysis demonstrated that MWA was associated with shorter operation time (standardized mean difference [SMD] =-1.37, 95% CI =-1.92 to -0.81, P=0.000), less amount of blood loss in operation (SWD =-1.19, 95% CI =-1.76 to -0.61, P=0.000), and less complications (OR =0.22, 95% CI =0.12-0.40, P=0.000) than HRN.

CONCLUSION

In conclusion, our meta-analysis suggests that MWA may be superior to HRN as it is as effective as HRN in terms of overall survival, disease-free survival, tumor recurrence, and is associated with shorter operation time, less amount of blood loss, and fewer complications.

Microwave ablation for the treatment of hepatocellular carcinoma that met up-to-seven criteria: feasibility, local efficacy and long-term outcomes

OBJECTIVES

This study aimed to evaluate the feasibility, local efficacy and long-term outcomes of microwave (MW) ablation for the treatment of hepatocellular carcinoma (HCC) that met up-to-seven criteria.

METHODS

Between January 2007 and January 2012, 142 HCC patients with 294 nodules, which conformed to up-to-seven criteria, were enrolled into this retrospective study. All patients were followed up for more than 3 years after receiving MW ablation. Technical success, complications, local tumour progression (LTP) and distant recurrence (DR) were monitored. Recurrence-free survival (RFS), overall survival (OS) and prognostic factors were analysed.

RESULTS

Primary technical efficacy was achieved in 95.2% (280/294) of the carcinomatous nodules, and major complications occurred in four (2.8%) patients. Among the 294 tumours, LTP was observed in 44 (15.0%) tumours. Among the 142 patients, DR was observed in 97 (68.3%) patients. The estimated OS rates after MW ablation at 1, 3 and 5 years were 97.2%, 75.4% and 50.6%, respectively; and the corresponding RFS rates were 76.1%, 33.1% and 19.5%, respectively.

CONCLUSIONS

MW ablation is a safe and effective treatment with a high rate of primary technical efficacy for patients with HCC that met up-to-seven criteria.

KEY POINTS

• The first study expanding MW ablation to HCC category beyond Milan criteria. • The first report that used up-to-seven criteria as indications for MW ablation. • HCC of up-to-seven criteria viewed as a subgroup of BCLC stage B. • MW ablation is safe and effective for treating HCC within up-to-seven criteria. • MW ablation is preferable in treating unresectable HCC within up-to-seven criteria.

Microwave ablation in primary and secondary liver tumours: technical and clinical approaches

Thermal ablation is increasingly being utilised in the treatment of primary and metastatic liver tumours, both as curative therapy and as a bridge to transplantation. Recent advances in high-powered microwave ablation systems have allowed physicians to realise the theoretical heating advantages of microwave energy compared to other ablation modalities. As a result there is a growing body of literature detailing the effects of microwave energy on tissue heating, as well as its effect on clinical outcomes. This article will discuss the relevant physics, review current clinical outcomes and then describe the current techniques used to optimise patient care when using microwave ablation systems.

Status and advancement of microwave ablation in China

Tumour ablation is defined as the direct application of chemical or thermal therapy to eradicate or substantially destroy a tumour. Currently, minimally invasive ablation techniques are available for the local destruction of focal tumours in multiple organ sites. Microwave ablation (MWA) is premised on the biological response of solid tumours to tissue hyperthermia, and it is a relatively low-risk procedure. Due to several advantages of MWA, including higher thermal efficiency, higher capability for coagulating blood vessels, faster ablation time and the simultaneous application of multiple antennae, MWA could be a promising minimally invasive ablation technique for the treatment of solid tumours. Therefore, the use of MWA has developed rapidly in China during the last decade. Many successful studies have been performed, and widespread use has been achieved for multiple types of tumours in China, especially for liver cancer. This review will describe the state-of-the-art of MWA in China, including the development of MWA equipment and its application in the treatment of multiple types of tumours.

Thermal ablation for hepatocellular carcinoma: a large-scale analysis of long-term outcome and prognostic factors

AIM

To investigate the long-term outcome and prognostic factors when treating hepatocellular carcinoma (HCC) with thermal ablation.

MATERIALS AND METHODS

A total of 846 HCC patients, diagnosed histopathologically and/or radiologically, underwent thermal ablation from October 2001 to May 2013. Thermal ablation included both radiofrequency ablation (RFA) and microwave ablation (MWA), and was performed by percutaneous, open, and laparoscopic approaches. Clinical data, especially focused on disease-free survival, were retrospectively analysed by univariate and multivariate analyses.

RESULTS

A total of 1,185 thermal ablation treatments were performed, corresponding to 1,240 tumours. The complete ablation rate was 97.1%. The 12-, 24-, 36-, and 60-month disease-free survival rates after thermal ablation were 72.3%, 52.7%, 33.5%, and 16.1%, respectively. Multivariate analysis indicated that the serum alkaline phosphatase levels (ALP) and the number of tumours were independent risk factors affecting disease-free survival. The 12-, 36-, 60-, 84-, and 120-month overall survival rates of all patients were 92.9%, 74.7%, 58.1%, 41.3%, and 15.8%, respectively. Multivariate analysis indicated that age, ALP, number of tumours, and treatment sessions per case were independent risk factors related to overall survival.

CONCLUSIONS

Thermal ablation was a relatively safe and effective procedure. Patients with increased serum ALP levels and/or multiple tumours had a higher incidence of recurrence and poorer prognosis, and therefore, should be monitored closely in clinical practice.