Assessment of Radiofrequency Ablation Efficacy for Hepatocellular Carcinoma by Histology and Pretransplant Radiology

Evolving Landscape in Liver Transplantation for Hepatocellular Carcinoma: From Stage Migration to Immunotherapy Revolution

Liver transplantation (LT) represents the primary curative option for HCC. Despite the extension of transplantation criteria and conversion with down-staging loco-regional treatments, transplantation is not always possible. The introduction of new standards of care in advanced HCC including a combination of immune checkpoint inhibitor-based therapies led to an improvement in response rates and could represent a promising strategy for down-staging the tumor burden. In this review, we identify reports and series, comprising a total of 43 patients who received immune checkpoint inhibitors as bridging or down-staging therapies prior to LT. Overall, treated patients registered an objective response rate of 21%, and 14 patients were reduced within the Milan criteria. Graft rejection was reported in seven patients, resulting in the death of four patients; in the remaining cases, LT was performed safely after immunotherapy. Further investigations are required to define the duration of immune checkpoint inhibitors, their minimum washout period and the LT long-term safety of this strategy. Some randomized clinical trials including immunotherapy combinations, loco-regional treatment and/or tyrosine kinase inhibitors are ongoing and will likely determine the appropriateness of immune checkpoint inhibitors' administration before LT.

Factors Associated With Complete Pathologic Necrosis of Hepatocellular Carcinoma on Explant Evaluation After Locoregional Therapy: A National Analysis Using the UNOS Database

BACKGROUND. Complete pathologic necrosis (CPN) is associated with improved survival in patients who undergo liver transplant (LT) after locoregional therapy (LRT) for hepatocellular carcinoma (HCC). OBJECTIVE. The purpose of this article was to identify patient, HCC, and transplant center characteristics associated with rates of CPN on explant evaluation using a large national sample of patients undergoing LT after LRT for HCC measuring 3 cm or smaller. METHODS. This retrospective study used data from the United Network for Organ Sharing database. The study included 6265 adults (median age, 62 years; 1505 women, 4760 men) who underwent LT after a single type LRT (either transarterial chemoembolization [TACE], thermal ablation, or transarterial radioembolization [TARE]) for HCCs measuring 3 cm or smaller at one of 118 U.S. transplant centers from April 12, 2012, to March 31, 2020. Patients were classified as having CPN if explant evaluation showed 100% necrosis of all HCCs. Associations with CPN were explored. Centers were categorized into tertiles on the basis of center-level CPN rates, and tertiles were compared. RESULTS. LRT was performed by TACE in 69.5% (4352/6265), thermal ablation in 19.4% (1217/6265), and TARE in 11.1% (696/6265) of patients. CPN rate was 18.5% (805/4352) after TACE, 35.8% (436/1217) after thermal ablation, 33.6% (234/696) after TARE, and 23.5% (1475/6265) overall. In multivariable analysis incorporating age, sex, model for end-stage liver disease score, α-fetoprotein level before LRT, wait list time, number of HCCs, HCC size, and the transplant center (as a random factor), use of thermal ablation (OR, 2.19; 95% CI, 1.86-2.57; p < .001) or TARE (OR, 1.92; 95% CI, 1.57-2.36; p < .001), with TACE as reference, independently predicted greater likelihood of CPN. Center-level CPN rates ranged from 0.0% to 50.0%. Stratifying centers by CPN rates, ablation was performed more frequently than TACE in 5.0% of centers in the first, 15.4% in the second, and 23.1% in the third tertiles (p = .07). CONCLUSION. CPN rate on explant evaluation was low. Thermal ablation or TARE, rather than TACE, was associated with higher likelihood of CPN in patient-level and center-level analyses. CLINICAL IMPACT. Findings from this large national sample support a potential role of thermal ablation or TARE for achieving CPN of HCC measuring 3 cm or smaller.

Hepatocellular carcinoma downstaging for liver transplantation in the era of systemic combined therapy with anti-VEGF/TKI and immunotherapy

Hepatocellular carcinoma remains a global health challenge affecting close to 1 million cases yearly. Liver transplantation provides the best long-term outcomes for those meeting strict criteria. Efforts have been made to expand these criteria, whereas others have attempted downstaging approaches. Although locoregional approaches to downstaging are appealing and have demonstrated efficacy, limitations and challenges exists including poor imaging modality to assess response and appropriate endpoints along the process. Recent advances in systemic treatments including immune checkpoint inhibitors alone or in combination with tyrosine kinase inhibitors have prompted the discussion regarding their role for downstaging disease prior to transplantation. Here, we provide a review of prior locoregional approaches for downstaging, new systemic agents and their role for downstaging, and finally, key and critical considerations of the assessment, endpoints, and optimal designs in clinical trials to address this key question.

Safety and efficacy of percutaneous radiofrequency ablation for hepatocellular carcinoma: a textbook outcome analysis

BACKGROUND

The Textbook Outcome (TO) is a quality indicator accounting for both efficacy and safety. Herein, we aimed to assess TO in patients with hepatocellular carcinoma (HCC) undergoing percutaneous radiofrequency ablation (RFA).

METHODS

All consecutive patients undergoing RFA for HCC between 2014 and 2020, were included. TO was defined as 1) no post-RFA complications or mortality within 30 days after RFA, 2) no prolonged hospital stay 3) no 30-day readmission and 4) the achievement of a complete response (CR) of the target lesion/s at 1-month.

RESULTS

Overall, 50.3% of 376 patients fulfilled all the quality indicators to achieve TO. Probabilities of TO achievement decreased in presence of moderate comorbidities (odds ratio[OR]:0.43; 95%C.I.:0.22-0.80;p=0.008), a performance status of 1 (OR: 0.58;95%C.I.:0.37-0.89; p=0.013), the treatment of 2 nodules (OR: 0.71; 95%C.I.:0.41-0.98; p=0.048) or ≥3 nodules (OR: 0.41; 95%C.I.: 0.22 - 0.78; p = 0.007); the treatment of 2-3cm nodules (OR:0.49;95%C.I.:0.31-0.79;p=0.003) or >3cm nodules (OR: 0.36;95%C.I.:0.18-0.73;p=0.004). Risk-stratification provided TO achievement ranging between 77.9% and 14.3%. Patients with TO also had improved survival (p = 0.028).

CONCLUSION

About half of patients get TO from RFA. Stratification by clinical and tumoral characteristic should aid provision of RFA in clinical practice, facilitating patient information and providing reference values for future comparative studies.

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.

Value of 18F-FDG PET/MRI in the early evaluation of treatment response following radiofrequency ablation of liver cancer in a rabbit model

PURPOSE

To test the hypothesis that ¹⁸F-fluorodeoxyglucose positron emission tomography and MRI (18F-FDG PET/MRI) can detect early residual tumor following radiofrequency ablation (RFA) of liver cancer using a VX2 tumor model.

METHODS

Twenty-four rabbits with VX2 liver tumors were randomly divided into three groups (n = 8/group): group 1 without RFA treatment, group 2 with complete ablation, and group 3 with partial ablation. ¹⁸F-FDG PET/MRI scan was obtained in three animal groups within 2 hours post-RFA. The maximum standardized uptake value (SUVmax) of non-treated liver tumor, benign peri-ablational enhancement (BPE), residual tumor, ablated tumor, adjacent liver parenchyma, and mean SUV of normal liver were measured, respectively. The ratios of SUVmax for these targets to mean SUV of normal liver (TNR) were calculated and statistically compared.

RESULTS

The mean TNR of non-treated liver tumors in group 1 was significantly greater than that of adjacent liver parenchyma (8.68 ± 0.71 vs 1.89 ± 0.26, p < 0.001). In group 2, the mean TNR of BPE was significantly greater than that of adjacent liver parenchyma (2.85 ± 0.20 vs 1.86 ± 0.25, p < 0.001). In group 3, the mean TNR of residual tumor was significantly greater than that of BPE (8.64 ± 0.59 vs 2.78 ± 0.23, p < 0.001), which was significantly greater than that of completely ablated tumor (2.78 ± 0.23 vs 0.50 ± 0.06, p < 0.001).

CONCLUSION

¹⁸F-FDG PET/MRI may serve as a promising imaging tool for early detection of viable residual tumors due to incomplete tumor ablation.

Baseline Alpha-Fetoprotein, Alpha-Fetoprotein-L3, and Des-Gamma-Carboxy Prothrombin Biomarker Status in Bridge to Liver Transplant Outcomes for Hepatocellular Carcinoma

Simple Summary

An abnormal alpha-fetoprotein (AFP) test is often associated with hepatocellular carcinoma (HCC) development, although as many as 40% of HCC diagnoses are made in the absence of an abnormal AFP test. In Japan and other Asian countries, Lens culinaris agglutinin-reactive AFP fraction (AFP-L3) and des-gamma-carboxy prothrombin (DCP) are used in combination with AFP for HCC diagnosis. Combined testing with all three biomarkers increases early diagnosis in addition to providing a patient-specific profile of HCC aggressiveness. The utility of AFP, AFP-L3, and DCP for HCC prognosis in the bridge to liver transplantation has not been established. The goal of this study is to define prognosis to first-line HCC treatment and the risk of progression prior to liver transplantation associated with biomarker profile at diagnosis. Biomarker profiling may have future implications in precision therapeutic management of HCC as a bridge to transplantation.

Abstract

The biomarkers α-fetoprotein (AFP), Lens culinaris agglutinin-reactive AFP fraction (AFP-L3), and des-γ-carboxy prothrombin (DCP) have emerging implications in hepatocellular carcinoma (HCC) surveillance, overall prognosis, and post-surgical recurrence risk. This retrospective study investigated treatment and bridge to liver transplant (LT) prognosis associated with AFP, AFP-L3%, and DCP biomarker profiles prior to liver-directed therapy (LDT). In a 140-patient cohort, each biomarker was associated with HCC progression risk using the established thresholds of AFP > 20 ng/mL, AFP-L3 > 15%, and DCP > 7.5 ng/mL. Over 60% of the cohort expressed at least one biomarker at baseline. Although most biomarker-positive patients expressed the clinical standard AFP (57/87), only 32% were positive for AFP alone. Biomarker accumulation increased HCC progression risk but was not associated with demographic factors or preserved liver function. Biomarker triple negative patients had smaller index HCC (p = 0.003), decreased multifocal burden (p = 0.010), and a higher objective response rate (ORR, 62% compared to 46%, p = 0.011). Expressing all three biomarkers at baseline was associated with dismal first-line ORR (12%) with a median time to progression (TTP) of only 181 days post-LDT. Patients with triple negative status for the HCC biomarkers AFP, AFP-L3%, and DCP have the highest first-line ORR with < 5% HCC progression 1-year post-LDT. Biomarker profiling can establish baseline prognosis for identifying optimal bridge to LT and downstaging to LT candidates with triple negative biomarker status and providing an ideal post-LDT target as a compliment to radiographic response.

Microwave Ablation of Very-Early- and Early-Stage HCC: Efficacy Evaluation by Correlation with Histology after Liver Transplantation

Microwave (MW) ablation is a worldwide-diffused technique for the percutaneous ablation of hepatocellular carcinoma (HCC). Nevertheless, the efficacy of this technique still needs to be confirmed in pathological specimens. The purpose of this study was to evaluate the efficacy of MW ablation by correlation with histology in excised liver samples at the time of liver transplantation (LT). All patients with MW-ablated HCC who subsequently underwent LT between 2012 and 2020 were retrospectively evaluated. In the explanted livers, the treated lesions were evaluated at pathology, and the necrosis was classified as complete or partial. Thirty-six HCCs were ablated in 30 patients (20.9 ± 6.1 mm, a range of 10-30 mm). Ablations were performed with a single insertion of a MW antenna under ultrasound or CT guidance. A complete radiological response was demonstrated in 30/36 nodules (83.3%) in 24/30 patients (80%) at imaging performed one-month after MW ablation. At pathology, of the 36 treated nodules, 28 (77.8%) showed a complete necrosis, and 8 (22.2%) showed a pathological partial necrosis. Good agreement was found between the imaging performed one-month after treatment and the complete pathological response (Cohen's k = 0.65). The imaging accuracy in detecting a complete response to treatment was 88.9%. All lesions with complete necrosis did not show recurrence at follow-up imaging until transplantation. The rad-path correlation in the explanted livers showed that MW ablation achieved a high rate of complete necrosis if a macroscopical complete ablation was obtained.

The (Eternal) Debate on Microwave Ablation Versus Radiofrequency Ablation in BCLC-A Hepatocellular Carcinoma

BACKGROUND/AIM

While percutaneous radiofrequency ablation (RFA) is considered the standard ablative modality for the treatment of early-stage hepatocellular carcinoma (HCC), percutaneous microwave ablation (MWA) is being increasingly used in recent years. We performed a systematic review and meta-analysis to compare percutaneous MWA versus percutaneous RFA in BCLC-A HCC across randomized controlled trials (RCTs).

PATIENTS AND METHODS

Eligible studies included RCTs assessing MWA versus RFA in BCLC-A HCC. Outcomes of interest included: complete ablation (CA) rate, local recurrence (LR) rate, 1-year overall survival (OS) rate, 3-year OS rate and major complications rate.

RESULTS

We retrieved all the relevant RCTs through PubMed/Medline, Cochrane library and EMBASE; five eligible studies involving a total of 794 patients (MWA: 409; RFA: 385) and 1008 nodules of HCC (MWA: 519; RFA: 489) were included in our analysis. No significant differences were found between MWA and RFA regarding CA, LR, 3-year OS and major complications rate. Regarding 1-year OS, a higher rate was observed in the MWA group.

CONCLUSION

MWA and RFA are effective and safe techniques in early stage, BCLC-A, HCCMWA resulted in better 1-year OS, although this benefit was not confirmed in the 3-year analysis.

Inter-center agreement of mRECIST in transplanted patients for hepatocellular carcinoma

OBJECTIVES

To evaluate the inter-observer reliability of modified Response Evaluation Criteria In Solid Tumours (mRECIST) of patients with hepatocellular carcinoma (HCC) undergoing neo-adjuvant treatments before liver transplant (LT). The agreement of tumor number, size, transplant criteria, and the radiological-pathological concordance were also assessed.

METHODS

A total of 180 radiological studies before/after neo-adjuvant therapies performed on 90 patients prior to LT were reviewed from three expert centers. Kappa-statistic and intraclass correlation (ICC) were evaluated on mRECIST and on tumoral features. Complete radiological response (CR) was compared with complete pathological response (CPR).

RESULTS

Before neo-adjuvant therapies, the agreement on tumor number, size, and transplant criteria ranged from moderate (defined as ICC of 0.41-0.60) to almost perfect (ICC of 0.81-0.99), being higher with magnetic resonance imaging (MRI) than CT (0.657-0.899 and 0.422-0.776, respectively). After neo-adjuvant therapies, the agreement decreased, as ICCs ranged between 0.518 and 0.663 with MRI and between 0.508 and 0.677 with CT. Concordant mRECIST pairs were 201 of 270 reviews (76.3%) with a kappa of 0.648 indicating substantial agreement. When the three observers completely agreed on CR, the positive predictive value for CPR was 51.6%. The negative predictive value was 94.2% with a kappa of 0.512 indicating fair agreement between radiology and pathology.

CONCLUSIONS

mRECIST agreement was substantial among the three observers involved. The agreement on tumor number, size, and transplant criteria ranged from moderate to almost perfect, with the highest ICCs obtained with MRI before neo-adjuvant therapies. Finally, the predictive value of mRECIST in the diagnosis of CPR was only fair.

KEY POINTS

• The review of 180 radiological exams of patients with hepatocellular carcinoma before and after neo-adjuvant therapies showed that the concordance among three different raters on mRECIST diagnosis was substantial. • The inter-observer reliability on fulfilment of transplant criteria slightly decreased when evaluated through CT and after loco-regional therapies. • The radiological diagnosis of complete response after neo-adjuvant therapies was predictive of complete pathological response in only 51.6% of cases.

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.

Including mRECIST in the Metroticket 2.0 criteria improves prediction of hepatocellular carcinoma-related death after liver transplant

BACKGROUND & AIMS

In the context of liver transplantation (LT) for hepatocellular carcinoma (HCC), prediction models are used to ensure that the risk of post-LT recurrence is acceptably low. However, the weighting that 'response to neoadjuvant therapies' should have in such models remains unclear. Herein, we aimed to incorporate radiological response into the Metroticket 2.0 model for post-LT prediction of "HCC-related death", to improve its clinical utility.

METHODS

Data from 859 transplanted patients (2000-2015) who received neoadjuvant therapies were included. The last radiological assessment before LT was reviewed according to the modified RECIST criteria. Competing-risk analysis was applied. The added value of including radiological response into the Metroticket 2.0 was explored through category-based net reclassification improvement (NRI) analysis.

RESULTS

At last radiological assessment prior to LT, complete response (CR) was diagnosed in 41.3%, partial response/stable disease (PR/SD) in 24.9% and progressive disease (PD) in 33.8% of patients. The 5-year rates of "HCC-related death" were 3.1%, 9.6% and 13.4% in those with CR, PR/SD, or PD, respectively (p <0.001). Log₁₀AFP (p <0.001) and the sum of number and diameter of the tumour/s (p <0.05) were determinants of "HCC-related death" for PR/SD and PD patients. To maintain the post-LT 5-year incidence of "HCC-related death" <30%, the Metroticket 2.0 criteria were restricted in some cases of PR/SD and in all cases with PD, correctly reclassifying 9.4% of patients with "HCC-related death", at the expense of 3.5% of patients who did not have the event. The overall/net NRI was 5.8.

CONCLUSION

Incorporating the modified RECIST criteria into the Metroticket 2.0 framework can improve its predictive ability. The additional information provided can be used to better judge the suitability of candidates for LT following neoadjuvant therapies.

LAY SUMMARY

In the context of liver transplantation for patients with hepatocellular carcinoma, prediction models are used to ensure that the risk of recurrence after transplantation is acceptably low. The Metroticket 2.0 model has been proposed as an accurate predictor of "tumour-related death" after liver transplantation. In the present study, we show that its accuracy can be improved by incorporating information relating to the radiological responses of patients to neoadjuvant therapies.

Conformal coverage of liver tumors by the thermal coagulation zone in 2450-MHz microwave ablation

Purpose: To optimize treatment schemes using 2450-MHz microwave ablation (MWA), a novel conformal coverage method based on bipolar-angle mapping is proposed that determines whether a liver tumor is completely encompassed by thermal coagulation zones. Materials and methods: Firstly, three-dimensional (3-D) triangular mesh data of liver tumors were reconstructed from clinical computed tomography (CT) slices using the Marching cubes (MC) algorithm. Secondly, characterization models of thermal coagulation zones were established based on finite element simulation results of 40, 45, 50, 55, and 60 W ablations. Finally, coagulation zone models and tumor surface data were mapped and fused on a two-dimensional (2-D) plane to achieve conformal coverage of liver tumors by comparing the corresponding polar radii. Results: Optimal parameters for ablation treatment of liver tumors were efficiently obtained with the proposed conformal coverage method. Fifteen liver tumors were obtained with maximal diameters of 12.329-78.612 mm (mean ± standard deviation, 39.094 ± 19.447 mm). The insertion positions and orientations of the MWA antenna were determined based on 3-D reconstruction results of these tumors. The ablation patterns and durations of tumors were planned according to the minimum mean standard deviations between the ablative margin and tumor surface. Conclusion: The proposed method can be applied to computer-assisted MWA treatment planning of liver tumors, and is expected to guide clinical procedures in future.

Analgesia of percutaneous thermal ablation plus cementoplasty for cancer bone metastases

Background

The purpose of this study was to review recent research related to the analgesic effect of ablation therapy combined with cementoplasty, as well as to identify the duration of analgesic effect and risk for cement leaks.

Methods

A systematic literature search using PubMed, Web of Science, and annual meeting proceedings of the oncology society and other organizations were conducted.

Results

Twelve retrospective studies met the inclusion criteria. Four of the studies included in the review assessed the changes immediately after treatment. Five studies were subjected to analyses of analgesic effect of combined percutaneous thermal ablation and Cementoplasty at 24 weeks after treatment. Incidences of leakage of bone cement during surgery were detected in 4 out of 12 studies. The change of mean pain scores at 1 days, at 1 week, and at 4 weeks, 12 weeks, and 24 weeks after treatment were -3.90 (95% CI: -4.80 to -3.00), -4.55 (95% CI:-5.46 to -3.64), -4.78 (95% CI: -5.70 to -3.86), -5.16 (95% CI: -6.39 to -3.92), and -5.91 (95% CI: -6.63 to -5.19). The relative risk of cement leakage was 0.10 (95% CI: -6.63 to -5.19).

Conclusions

Our systematic review suggested that thermal ablation combined with cementoplasty could be a safe and effective intervention for the management of bone metastases-induced pain.