Microwave Ablation For Treatment Research Articles

Microwave ablation followed by cTACE in 5-cm HCC lesions: does a single-session approach affect liver function?

Microwave ablation (MWA) and conventional transarterial chemoembolization (cTACE) are locoregional treatments commonly performed in very early, early and intermediate stages of hepatocellular carcinoma (HCC). Despite combined locoregional approaches have shown encouraging results in obtaining complete tumor necrosis, their application in a single session is poorly described. Our aim was to evaluate the safety and efficacy of single-session MWA and cTACE treatment in 5-cm HCCs and its influence on liver function. All 5-cm HCCs treated by MWA and cTACE performed in a single-session in our Interventional Radiology unit between January 2020 and December 2022 were retrospectively recorded and analyzed. Patients with poor or missing pre- and post-treatment imaging were excluded. Technical success, clinical success, and complications rate were examined as primary endpoints. Pre- and post-treatment liver function laboratory parameters were also evaluated. A total of 15 lesions (mean lesion diameter, 5.0 ± 1.4cm) in 15 patients (11 men; mean age, 67.1 ± 8.9 years) were retrospectively evaluated. Technical and clinical success were 100% and 73%, respectively. Four (27%) cases of partial response and no cases of progressive or stable disease were recorded. AST and ALT values have found to be significantly higher in post-treatment laboratory tests. No other significant differences between pre- and post-treatment laboratory values were registered. AST and ALT pre- and post-treatment higher differences (ΔAST and ΔALT) were significantly associated with a lower clinical success rate. MWA and cTACE single-session approach is safe and effective for 5-cm HCCs, without significant liver function impairment. A post-treatment increase in AST and ALT values may be a predictor for clinical failure.

Experimental study for in vitro prostate cancer treatment with microwave ablation and pulsed electromagnetic field

ABSTRACT This paper presents the findings of a comprehensive study exploring the synergistic effects arising from the combination of microwave ablation and pulsed electromagnetic field (PEMF) therapy on prostate cancer cells. The research encompassed five distinct experimental groups, with continuous electric field measurements conducted during the entire treatment process. Group 1 and Group 2, subjected to microwave power below 350 W, exhibited specific electric field values of 72,800 V/m and 56,600 V/m, respectively. In contrast, Group 3 and Group 4, exposed to 80 W microwave power, displayed electric field levels of approximately 1450 V/m, while remaining free from any observable electrical discharges. The migratory and invasive capacities of PC3 cells were assessed through a scratch test in all groups. Notably, cells in Group 3 and Group 4, subjected to the combined treatment of microwave ablation and PEMF, demonstrated significantly accelerated migration in comparison to those in Groups 1 and 2. Additionally, Group 5 cells, receiving PEMF treatment in isolation, exhibited decreased migratory ability. These results strongly suggest that the combined approach of microwave ablation and PEMF holds promise as a potential therapeutic intervention for prostate cancer, as it effectively reduced cell viability, induced apoptosis, and impeded migration ability in PC3 cells. Moreover, the isolated use of PEMF demonstrated potential in limiting migratory capacity, which could hold critical implications in the fight against cancer metastasis.

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.

Predicting Microwave Ablation Early Efficacy in Pulmonary Malignancies via Δ Radiomics Models.

This study aimed to explore the value of preoperative and postoperative computed tomography (CT)-based radiomic signatures and Δ radiomic signatures for evaluating the early efficacy of microwave ablation (MWA) for pulmonary malignancies. In total, 115 patients with pulmonary malignancies who underwent MWA treatment were categorized into response and nonresponse groups according to relevant guidelines and consensus. Quantitative image features of the largest pulmonary malignancies were extracted from CT noncontrast scan images preoperatively (time point 0, TP0) and immediately postoperatively (time point 1, TP1). Critical features were selected from TP0 and TP1 and as Δ radiomics signatures for building radiomics models. In addition, a combined radiomics model (C-RO) was developed by integrating radiomics parameters with clinical risk factors. Prediction performance was assessed using the area under the receiver operating characteristic curve (AUC) and decision curve analysis (DCA). The radiomics model using Δ features outperformed the radiomics model using TP0 and TP1 features, with training and validation AUCs of 0.892, 0.808, and 0.787, and 0.705, 0.825, and 0.778, respectively. By combining the TP0, TP1, and Δ features, the logistic regression model exhibited the best performance, with training and validation AUCs of 0.945 and 0.744, respectively. The DCA confirmed the clinical utility of the Δ radiomics model. A combined prediction model, including TP0, TP1, and Δ radiometric features, can be used to evaluate the early efficacy of MWA in pulmonary malignancies.

Transapical intramyocardial septal microwave ablation in treatment of hypertrophic obstructive cardiomyopathy: 12-month outcomes of a swine model

BackgroundTo date, the extended Morrow procedure is considered the gold standard treatment for patients with obstructive hypertrophic cardiomyopathy who experience severe symptoms and are unresponsive to medication treatment. We therefore aimed to perform transapical intramyocardial septal microwave ablation to reduce the thickness of the interventricular septum myocardium in a minimally invasive method.MethodsFourteen swine were divided to form either a microwave ablation group (n = 7) or a sham group (n = 7). In the microwave ablation group, a transapical microwave antenna was inserted into the septum to ablate each myocardial segment at 40 W for 1 min, while in the sham group, the same operation was performed but without power output. We used echocardiography, electrocardiogram, during the operation. And added computerized tomography, cardiac nuclear magnetic resonance during follow-up.ResultsSegment hypokinesis was observed in all swine immediately following ablation. Compared with the sham group, the thickness of ablated segments in the ablation group decreased significantly 1 month post-operation (ablation group, 5.53 ± 1.00 mm vs. 8.03 ± 1.15 mm, respectively, P < 0.01; sham group, 8.40 ± 0.94 mm vs. 8.21 ± 1.09 mm, respectively, P = 0.081), and the outcome was still observed 1 year post-operation (ablation group, 3.36 ± 0.85 mm vs. 8.03 ± 1.15 mm, respectively, P < 0.01). No perforation of the septum was observed during the procedure or follow-up, and no heart failure or sudden cardiac death occurred during postoperative feeding.ConclusionsTransapical intramyocardial septal microwave ablation can effectively and safely produce a large region of necrosis. This technique can potentially mimic surgical myectomy while avoiding cardiopulmonary bypass and median sternotomy in high-risk hypertrophic obstructive cardiomyopathy patients.

Efficacy of microwave ablation with parallel acupuncture guided by ultrasound in treating single hepatocellular carcinoma in high-risk areas: A retrospective analysis of 155 patients.

To investigate the safety and short- and long-term efficacy of ultrasound-guided microwave ablation (MWA) with parallel acupuncture for treating single hepatocellular carcinoma (HCC) in high-risk areas. Retrospective analysis was performed on 155 patients with single hepatocellular carcinoma who underwent microwave ablation in our hospital between December 2015 and September 2016. Patients with a tumor distance of ≤5 mm from the risk area were included in the observation group. Patients with a tumor distance of >5 mm from the risk area were placed in the control group. The patients' preoperative general health status, tumor site, tumor size, follow-up data, disease-free survival rate, overall survival rates, local tumor progression, and intrahepatic distant recurrence rate were collected and analyzed. The 1-, 3-, and 5-year overall survival rates for the observation group were 91.8%, 75.5%, and 59.2%, respectively. The 1-, 3-, and 5-year overall survival rates for the control group were 97.2%, 84.0%, and 66.0%, respectively. There were no significant differences between the two groups (P = 0.522). A tumor size of ≤20 mm (HR = 0.488, 95% CI = 0.254-0.940, P = 0.032) was an independent risk factor affecting the overall survival of patients with solitary HCC treated with MWA. The 1-, 3-, and 5-year recurrence-free survival rates for the observation group were 59.2%, 28.6%, and 18.4%, respectively, and those for the control group were 79.2%, 43.4%, and 31.1%, respectively. There was a statistical difference between the two groups (P = 0.007). Tumor size ≤20 mm (HR = 0.468, 95% CI = 0.303-0.723, P = 0.001), tumor location in a risk area (HR = 1.662, 95% CI = 1.121-2.465, P = 0.011), and an α-fetoprotein (AFP) level of <200 ug/L (HR = 0.612, 95% CI = 0.386-0.970, P = 0.036) are independent factors affecting the recurrence-free survival of MWA treatment for HCC. Microwave ablation with parallel acupuncture guided by ultrasound is a safe and effective treatment for single hepatocellular carcinoma in high-risk areas.

Preoperative systemic immune-inflammation index-based nomogram for lung carcinoma following microwave ablation -a real world single center study.

The preoperative inflammatory condition significantly influences the prognosis of malignancies. We aimed to investigate the potential significance of preoperative inflammatory biomarkers in forecasting the long-term results of lung carcinoma after microwave ablation (MWA). This study included patients who received MWA treatment for lung carcinoma from Jan. 2012 to Dec. 2020. We collected demographic, clinical, laboratory, and outcome information. To assess the predictive capacity of inflammatory biomarkers, we utilized the area under the receiver operating characteristic curve (AUC-ROC) and assessed the predictive potential of inflammatory biomarkers in forecasting outcomes through both univariate and multivariate Cox proportional hazard analyses. A total of 354 individuals underwent MWA treatment, of which 265 cases were included in this study, whose average age was 69.1 ± 9.7 years. The AUC values for the Systemic Inflammatory Response Index (SIRI) to overall survival (OS) and disease-free survival (DFS) were 0.796 and 0.716, respectively. The Cox proportional hazards model demonstrated a significant independent association between a high SIRI and a decreased overall survival (hazard ratio [HR]=2.583, P<0.001). Furthermore, a high SIRI independently correlated with a lower DFS (HR=2.391, P<0.001). We developed nomograms utilizing various independent factors to forecast the extended prognosis of patients. These nomograms exhibited AUC of 0.900, 0.849, and 0.862 for predicting 1-year, 3-year, and 5-year OS, respectively. Additionally, the AUC values for predicting 1-year, 3-year, and 5-year DFS were 0.851, 0.873, and 0.883, respectively. SIRI has shown promise as a valuable long-term prognostic indicator for forecasting the outcomes of lung carcinoma patients following MWA.

Numerical study of the induction of intratumoral apoptosis under microwave ablation by changing slot length of microwave coaxial antenna.

Recent advances in technology have led to an increase in the detection of previously undetected deep-located tumor tissue. As a result, the medical field is using a variety of methods to treat deep-located tumors, and minimally invasive treatment techniques are being explored. In this study, therapeutic effect of microwave ablation (MWA) on tumor generated inside liver tissue was analyzed through numerical analysis. The distribution of electromagnetic fields in biological tissues emitted by microwave coaxial antenna (MCA) was calculated through the wave equation, and the thermal behavior of the tissue was analyzed through the Pennes bioheat equation. Among various treatment conditions constituting MWA, tumor radius and the slot length inside the MCA were changed, and the resulting treatment effect was quantitatively confirmed through three apoptotic variables. As a result, each tumor radius has optimal power condition for MWA, 2.6W, 2.4W, and 3.0W respectively. This study confirmed optimal therapeutic conditions for MWA. Three apoptotic variables were used to quantitatively identify apoptotic temperature maintenance inside tumor tissue and thermal damage to surrounding normal tissue. The findings of this study are expected to serve as a standard for treatment based on actual MWA treatment.

Histology-validated electromagnetic characterization of ex-vivo ovine lung tissue for microwave-based medical applications

Microwave thermal ablation is an established therapeutic technique for treating malignant tissue in various organs. Its success greatly depends on the knowledge of dielectric properties of the targeted tissue and on how they change during the treatment. Innovation in lung navigation has recently increased the clinical interest in the transbronchial microwave ablation treatment of lung cancer. However, lung tissue is not largely characterized, thus its dielectric properties investigation prior and post ablation is key. In this work, dielectric properties of ex-vivo ovine lung parenchyma untreated and ablated at 2.45 GHz were recorded in the 0.5–8 GHz frequency range. The measured dielectric properties were fitted to 2-pole Cole–Cole relaxation model and the obtained model parameters were compared. Based on observed changes in the model parameters, the physical changes of the tissue post-ablation were discussed and validated through histology analysis. Additionally, to investigate the link of achieved results with the rate of heating, another two sets of samples, originating from both ovine and porcine tissues, were heated with a microwave oven for different times and at different powers. Dielectric properties were measured in the same frequency range. It was found that lung tissue experiences a different behavior according to heating rates: its dielectric properties increase post-ablation while a decrease is found for low rates of heating. It is hypothesized, and validated by histology, that during ablation, although the tissue is losing water, the air cavities deform, lowering air content and increasing the resulting tissue properties.

Clinical outcomes of percutaneous microwave ablation for pulmonary oligometastases from hepatocellular carcinoma: a retrospective, multicenter study

BackgroundPulmonary oligometastases are common in hepatocellular carcinoma (HCC), however, the existing therapeutic options have several limitations. This study aimed to assess the safety and efficacy of microwave ablation (MWA) in the treatment of HCC-originating pulmonary oligometastases.MethodsA total of 83 patients, comprising 73 males and 10 females with a median age of 57 years, who had pulmonary oligometastases from HCC, underwent MWA treatment at four different medical institutions. Inclusion criteria for patients involved having primary HCC under control and having less than three oligometastases with a maximum diameter of ≤ 5 cm in the unilateral lung or less than five oligometastases with a maximum diameter of ≤ 3 cm in the bilateral lung. A total of 147 tumors were treated with MWA over 116 sessions. The primary endpoints assessed included technical success, treatment efficacy, and local progression rate, while secondary endpoints encompassed complications, clinical outcomes, overall survival (OS), local progression-free survival (LPFS), and prognostic factors.ResultsThe technical success rate for MWA was 100% (116/116 sessions), and the treatment efficacy rate was 82.3% (121/147 tumors). Six months after MWA, the local progression rate was 23.1% (18/147 tumors). Complications were observed in 10.3% (major) and 47.4% (minor) of the 116 sessions, with no cases of ablation-related deaths. The median follow-up period was 21.6 months (range: 5.7–87.8 months). Median OS was 22.0 months, and the 1-, 2-, and 3-year OS rates were 82.6%, 44.5%, and 25.2%, respectively. Median LPFS was 8.5 months. Multivariate Cox regression analysis identified α-fetoprotein (AFP) levels during initial diagnosis and the number of oligometastases as potential independent prognostic factors for OS (p = 0.017 and 0.045, respectively).ConclusionPercutaneous MWA is a safe and effective treatment modality for pulmonary oligometastases originating from HCC.

Spatiotemporal modeling of nano-delivered chemotherapeutics for synergistic microwave ablation cancer therapy

Background and objectiveThe effectiveness of current microwave ablation (MWA) therapies is limited. Administration of thermosensitive liposomes (TSLs) which release drugs in response to heat has presented a significant potential for enhancing the efficacy of thermal ablation treatment, and the benefits of targeted drug delivery. However, a complete knowledge of the mechanobiological processes underlying the drug release process, especially the intravascular drug release mechanism and its distribution in response to MWA needs to be improved. Multiscale computational-based modeling frameworks, integrating different biophysical phenomena, have recently emerged as promising tools to decipher the mechanobiological events in combo therapies. The present study aims to develop a novel multiscale computational model of TSLs delivery following MWA implantation. MethodsDue to the complex interplay between the heating procedure and the drug concentration maps, a computational model is developed to determine the intravascular release of doxorubicin from TSL, its transvascular transport into the interstitium, transport in the interstitium, and cell uptake. Computational models can estimate the interplays among liposome and drug properties, tumor perfusion, and heating regimen to examine the impact of essential parameters and to optimize a targeted drug delivery platform. ResultsResults indicated that the synergy of TSLs with MWA allows more localized drug delivery with lower side effects. The drug release rate and tumor permeability play crucial roles in the efficacy of TSLs during MWA treatment. The computational model predicted an unencapsulated drug lime around the ablated zone, which can destroy more cancer cells compared to MWA alone by 40%. Administration of TSLs with a high release rate capacity can improve the percentage of killed cancer cells by 24%. Since the heating duration in MWA is less than 15 min, the presented combination therapy showed better performance for highly permeable tumors. ConclusionThis study highlights the potential of the proposed computational framework to address complex and realistic scenarios in cancer treatment, which can serve as the future research foundation, including advancements in nanomedicine and optimizing the pair of TSL and MWA for both preclinical and clinical studies. The present model could be as a valuable tool for patient-specific calibration of essential parameters.

MRI non-rigid registration with tumor contraction correction for ablative margin assessment after microwave ablation of hepatocellular carcinomas.

This study aims to develop and assess a tumor contraction model, enhancing the precision of ablative margin(AM) evaluation after microwave ablation (MWA) treatment for hepatocellular carcinomas (HCCs). &#xD;Approach: We utilize a probabilistic method called the Coherent Point Drift algorithm to align pre-and post-ablation MRI images. Subsequently, a nonlinear regression method quantifies local tumor contraction induced by MWA, utilizing data from 47 HCC with viable ablated tumors in post-ablation MRI. After automatic non-rigid registration, correction for tumor contraction involves contracting the 3D contour of the warped tumor towards its center in all orientations.&#xD;Main Results: We evaluate the performance of our proposed method on 30 HCC patients who underwent MWA. The Dice similarity coefficient between the post-ablation liver and the warped pre-ablation livers is found to be 0.95±0.01, with a mean corresponding distance between the corresponding landmarks measured at 3.25±0.62mm. Additionally, we conduct a comparative analysis of clinical outcomes assessed through MRI over a 3-month follow-up period, noting that the AM, as evaluated by our proposed method, accurately detects residual tumor after MWA.&#xD;Significance: Our proposed method showcases a high level of accuracy in MRI liver registration and AM assessment following ablation treatment. It introduces a potentially approach for predicting incomplete ablations and gauging treatment success.

Role of Percutaneous Microwave Ablation in Treatment of Osteoid Osteoma

Role of Percutaneous Microwave Ablation in Treatment of Osteoid Osteoma

Percutaneous microwave ablation versus sclerotherapy for large hepatic hemangioma: a multi-center cohort study

Objective The study aimed to compare the effectiveness and safety of ultrasound-guided microwave ablation (MWA) and percutaneous sclerotherapy (PS) for the treatment of large hepatic hemangioma (LHH). Methods This retrospective study included 96 patients who underwent MWA (n = 54) and PS (n = 42) as first-line treatment for LHH in three tertiary hospitals from January 2016 to December 2021. Primary outcomes were technique efficacy rate (volume reduction rate [VRR] > 50% at 12 months), symptom relief rate at 12 months and local tumor progression (LTP). Secondary outcomes included procedure time, major complications, treatment sessions, cost and one-, two-, three-year VRR. Results During a median follow-up of 36 months, the MWA group showed a higher technique efficacy rate (100% vs. 90.4%, p = .018) and symptom relief rate (100% vs. 80%, p = .123) than the PS group. The MWA group had fewer treatment sessions, higher one-, two- and three-year VRR, lower LTP rate (all p < .05), longer procedure time and higher treatment costs than the PS group (both p < .001). MWA shared a comparable major complications rate (1.8% vs. 2.4%, p = .432) with PS. After multivariate analysis, the lesion’s heterogeneity and maximum diameter >8.1 cm were independent risk factors for LTP (all p < .05). In the PS group, lesions with a cumulative dose of bleomycin > 0.115 mg/cm3 had a lower risk of LTP (p = .006). Conclusions Both MWA and PS treatments for large hepatic hemangioma are safe and effective, with MWA being superior in terms of efficacy.

Fe-doped Cu-based bimetallic metal-organic frameworks as nanoscale microwave sensitizers for enhancing microwave thermal and dynamic therapy for hepatocellular carcinoma.

Microwave ablation (MWA) is recognized as a novel treatment modality that can kill tumor cells by heating the ions and polar molecules in these cells through high-speed rotation and friction. However, the size and location of the tumor affect the effective ablation range of microwave hyperthermia, resulting in residual tumor tissue and a high recurrence rate. Due to their tunable porous structure and high specific surface area, metal-organic frameworks (MOFs) can serve as microwave sensitizers, promoting microwave energy conversion owing to ion collisions in the porous structure of the MOFs. Moreover, iron-based compounds are known to possess peroxidase-like catalytic activity. Therefore, Fe-doped Cu bimetallic MOFs (FCMs) were prepared through a hydrothermal process. These FCM nanoparticles not only increased the efficiency of microwave-thermal energy conversion as microwave sensitizers but also promoted the generation of reactive oxygen species (ROS) by consuming glutathione (GSH) and promoted the Fenton reaction to enhance microwave dynamic therapy (MDT). The in vitro and in vivo results showed that the combination of MWA and MDT treatment effectively destroyed tumor tissues via microwave irradiation without inducing significant side effects on normal tissues. This study provides a new approach for the combined application of MOFs and microwave ablation, demonstrating excellent potential for future applications.

Optimal parameters for the efficient microwave ablation of liver tumor from the 3D-IRCADb-01 database

Purpose Microwave ablation is a minimally invasive thermal modality for cancer treatment with high survival and low recurrence rates. Despite the unquestionable benefits of microwave ablation, the interaction between the medical instruments and the tissue may cause damage to the healthy tissue around the tumor. Such damages can be removed by clarifying the conditions for their development. In addition to clinical methods, computer simulations have become very effective tools for optimizing microwave ablation performance. Methods The study was focused on the determination of the optimal input power for complete microwave tumor ablation with an adequate safety margin avoiding injury to the surrounding healthy tissue. In three-dimensional simulations, the liver tumor model was based on a real tumor (1.74 cm x 2.40 cm x 1.43 cm) from the 3D-IRCADb-01 database. Calculations were performed for a 10-slot antenna proven to achieve a higher degree of ablation zone localization than a standard single-slot antenna. The temperature-dependent dielectric and thermal properties of healthy and tumoral liver tissue, blood perfusion, and water content were included in the model. Results The obtained simulation results revealed that the proper choice of input power ensures that necrotic tissue is mainly located in the tumor with minimal damage to the surrounding healthy tissue. Conclusions This study may represent a step forward in the planning of individual microwave ablation treatment for each patient.

Inducing the Abscopal Effect in Liver Cancer Treatment: The Impact of Microwave Ablation Power Levels and PD-1 Antibody Therapy.

Microwave ablation (MWA) is an effective treatment for liver cancer (LC), but its impact on distant tumors remains to be fully elucidated. This study investigated the abscopal effects triggered by MWA treatment of LC, at different power levels and with or without combined immune checkpoint inhibition (ICI). We established a mouse model with bilateral subcutaneous LC and applied MWA of varied power levels to ablate the right-sided tumor, with or without immunotherapy. Left-sided tumor growth was monitored to assess the abscopal effect. Immune cell infiltration and distant tumor neovascularization were quantified via immunohistochemistry, revealing insights into the tumor microenvironment and neovascularization status. Th1- and Th2-type cytokine concentrations in peripheral blood were measured using ELISA to evaluate systemic immunological changes. It was found that MWA alone, especially at lower power, promoted distant tumor growth. On the contrary, combining high-power MWA with anti-programmed death (PD)-1 therapy promoted CD8+ T-cell infiltration, reduced regulatory T-cell infiltration, upregulated a Th1-type cytokine (TNF-α) in peripheral blood, and inhibited distant tumor growth. In summary, combining high-power MWA with ICI significantly enhances systemic antitumor immune responses and activates the abscopal effect, offering a facile and robust strategy for improving treatment outcomes.

HPB P32 Ablative techniques in Colorectal Liver Metastases: A Systematic Review and Descriptive Summary of Practice

Abstract Background In the UK, over 40,000 patients are diagnosed with colorectal cancer annually. Many of these patients develop liver metastases. Although surgical resection is the gold-standard treatment for colorectal liver metastasis (CRLM), some patients are unsuitable for resection. Radiofrequency Ablation (RFA) and Microwave Ablation (MWA) are alternative treatments for CRLM. However, consensus is lacking regarding selection criteria, tumour characteristics, ablation technique delivery, and device settings. This systematic review summarises current evidence regarding selection criteria, treatment indications, and ablation delivery to inform future prospective studies. Methods A systematic review was conducted following PRISMA guidelines. Studies assessing RFA and MWA treatment of CRLM were identified in Medline, Embase, Web of Science and the Cochrane database of systematic reviews, from inception until 1st June 2021. Eligible studies included those reporting patient selection, tumour characteristics, treatment delivery, ablation device settings, and ablation outcomes for CRLM. Data extraction and analysis were performed. Results Forty-six studies were included (retrospective cohort n=40, prospective cohort n=4, non-randomized comparative studies n=2). Fifty-four inclusion criteria were used across 39 studies and were not stated in 7 studies. Tumours varied in mean number (1-8) and diameter (1.54-4.35cm). Neoadjuvant chemotherapy use (10-100% of patients), ablation delivery approach (Open n=4, laparoscopic n=11, percutaneous n=23, mixed n=2), anaesthetic mode (GA n=17, LA n=9, mixed n=2) and delivering clinician (radiologist n=8, surgeon n=15) all varied. Thirty studies lacked complete ablation device settings. Six studies followed a standardised ablation algorithm and 10 studies had specific settings. Five-year survival ranged from 0-69.7% for ablation. Conclusions There is significant heterogeneity in study design, patient selection, and ablation techniques for CRLM. The lack of standardized approaches and inconsistent reporting of methodology and outcomes make it challenging to determine the optimal ablative treatment for CRLM. Future research should focus on clearly defining selection and treatment criteria, as well as treatment delivery to facilitate generalisability. An RCT investigating ablation techniques may be difficult to implement due to a lack of clinician and patient equipoise, however, a high-quality, multi-centre nationwide prospective cohort study to investigate ablation as an alternative to surgery is required for high-risk patients with CRLM.

Value of contrast-enhanced ultrasonography in microwave ablation treatment of symptomatic focal uterine adenomyosis.

This study evaluated the value of contrast-enhanced ultrasonography (CEUS) in the ultrasound-guided microwave ablation (MWA) treatment of symptomatic focal uterine adenomyosis. This retrospective study was conducted between March 2020 and January 2023, enrolling 52 patients with symptomatic focal uterine adenomyosis who had undergone MWA. All patients were examined with CEUS before and after MWA. The non-perfused volume (NPV) was compared between CEUS and dynamic contrast-enhanced magnetic resonance imaging (DCEMRI) following ablation. Therapeutic efficacy and safety were evaluated at 3-, 6-, and 12-month follow-ups. Additionally, this study explored the correlations between pre-treatment CEUS features and a volume reduction ratio indicating sufficient ablation, defined as 50% or more at the 3-month follow-up. No significant differences in NPV were noted between CEUS and DCE-MRI immediately after MWA and during follow-up (all P>0.05). At the 3-month follow-up, the median VRRs for the uterus and adenomyosis were 33.2% and 63.9%, respectively. Sufficient ablation was achieved in 69.2% (36/52) of adenomyosis cases, while partial ablation was observed in the remaining 30.8% (16/52). The identification of non-enhancing areas on pre-treatment CEUS was associated with sufficient ablation (P=0.016). At the 12-month follow-up, significant decreases were observed in both the uterine and adenomyosis volumes (all P<0.001). Dysmenorrhea and menorrhagia were significantly alleviated at 12 months, and no major complications were encountered. CEUS can be used to evaluate the ablation zone of focal adenomyosis that has been treated with MWA, similarly to DCE-MRI. The identification of non-enhancing areas on pretreatment CEUS indicates satisfactory treatment outcomes.

Evaluation of local control after percutaneous microwave ablation versus partial nephrectomy: A propensity score matched study

IntroductionThe incidence of small renal tumors (≤4cm) is on the rise. The gold standard treatment is partial nephrectomy (PN) but focal therapy can be a good alternative. We evaluated oncological control after treatment of T1a renal tumors by microwave ablation (MWA) compared to PN. MethodsThis is a retrospective, single-center study of all patients treated for TNM stage T1a renal tumors by either PN or MWA between 2010 and 2020. A propensity score was calculated and patients were matched 2:1 to compare recurrence-free survival, metastasis-free survival and overall survival between groups. We also compared postoperative complications using the Clavien-Dindo classification. ResultsAfter matching and propensity score, the two groups (41 MWA and 82 PN) were comparable. The median follow-up was 23 months (interquartiles, 9–48 months). Recurrence-free survival was higher in the PN group compared to MWA, with a recurrence rate of 17.1% in the MWA group vs 4.9% in the PN group (P=0.003). MWA treatment was a risk factor for tumor recurrence (P=0.002), but there was no significant difference in terms of metastasis-free survival (P=0.549) or overall survival (P=0.539). MWA was associated with fewer postoperative complications (P=0.0005). ConclusionThis study shows that MWA was associated with higher risk of recurrence but similar metastasis-free survival and overall survival compared to PN. Recurrence was treated with new MWA or active surveillance. MWA may be an interesting alternative to PN for small renal tumors. Level of evidenceGrade C