Radiofrequency Thermal Ablation Research Articles

Percutaneous thermal radiofrequency rhizotomy of L2-S1 spinal nerve roots in children with cerebral palsy.

This study presents the results of an evaluation of the effectiveness of percutaneous thermal radiofrequency (RF) ablation of spinal nerve roots to reduce spasticity and improve motor function in children with cerebral palsy (CP). A retrospective analysis was conducted on the surgical treatment outcomes of 26 pediatric patients with severe CP (Gross Motor Function Classification System levels IV-V). The assessment protocol included muscle tone assessment using the modified Ashworth scale (MAS), evaluation of passive and active range of motion, gait video recording, and locomotor status evaluation using the Gross Motor Function Measure (GMFM)-88 scale. Thermal RF rhizotomy (ablation of spinal nerve roots) was performed on all patients at the L2-S1 levels at 70°C for 90 seconds. The statistical data analysis was conducted using the t-test and Mann-Whitney U-test. A p value < 0.05 was considered statistically significant. Before the operation, the average level of spasticity in the lower-limb muscles of all patients was 3.0 ± 0.2 according to the MAS. In the early postoperative period, the spasticity level in all examined muscle groups significantly decreased to a mean of 1.14 ± 0.15 (p < 0.001). In the long-term postoperative period, the spasticity level in the examined muscle groups averaged 1.49 ± 0.17 points on the MAS (p < 0.001 compared to baseline, p = 0.0416 compared to the early postoperative period). Despite the marked reduction of spasticity in the lower limbs, no significant change in locomotor status according to the GMFM-88 scale was observed in the selected category of patients. In the long-term period, during the control examination of patients, the GMFM-88 level increased on average by 3.6% ± 1.4% (from 22.2% ± 3.1% to 25.8% ± 3.6%). The findings of this study offer preliminary yet compelling evidence that RF ablation of spinal nerve roots can lead to a significant and enduring decrease in muscle tone among children with severe spastic CP. Further studies and longer-term data of the impact on functionality and quality of life of patients with CP after spinal root RF ablation are needed.

Enhancing palliative care in vulnerable patients: Robot-assisted radiofrequency ablation for multiple spinal metastases - Technical insights and preliminary outcomes.

Radiofrequency thermal ablation (RFA) coupled with vertebroplasty or kyphoplasty offers a minimally invasive, safe, and efficacious approach to palliate polymetastatic spine disease, particularly in medically fragile individuals. However, the application of robotic assistance to RFA for spinal metastases remains unexplored. This study elucidates the technical viability of robot-assisted RFA combined with vertebroplasty in patients afflicted by multiple spinal metastases and presents preliminary outcomes. An illustrative case was also presented. Ten patients aged over 65 years with multiple vertebral metastases were enrolled in this study. Preoperatively, patients exhibited a median Visual Analog Scale (VAS) pain score of 6 and a Median Oswestry Disability Index (ODI) score of 58%. From February 2021 to April 2022, all patients underwent RFA, followed by vertebroplasty for spinal metastases. Surgical procedures were executed using the ExcelsiusGPS® robotic platform. Patients experienced substantial pain relief, with a median VAS score of 2.5 at 24 h postoperatively (Δ --3.5; P < 0.001) and a median VAS score of 2 at 1 month postoperatively (Δ -4; P < 0.001). All patients were discharged on the first postoperative day and continued their oncological treatments. In addition, the median ODI score at 1 month postoperatively was 34% (Δ --24%; P = 0.006), indicating an enhanced quality of life and a satisfactory impact on daily activities. No procedural or postoperative complications were documented. This case series represents the inaugural successful application of robot-assisted RFA in conjunction with concurrent vertebroplasty/kyphoplasty. Our preliminary experience demonstrates that patients with oligo- and polymetastatic conditions can derive benefits from this minimally invasive intervention, characterized by rapid postoperative recovery and effective short- to medium-term pain management, without encountering complications.

Ultrasound-guided thermal radiofrequency ablation of the genicular nerves after total knee replacement

The rate of refractory chronic pain after total knee replacement (TKR) is 20–25%, with no identifiable etiology in 6% of cases. Without an etiologic diagnosis, the surgeon is unlikely to consider revision, but pain poses a therapeutic challenge for achieving satisfaction and an acceptable quality of life. Genicular nerve radiofrequency ablation (GNRFA) was recently developed as a non-drug analgesic option. It is minimally invasive and safe, with few adverse effects, opening a new perspective for management of refractory chronic pain after TKR. Level of evidenceIV.

Impact of temperature on the magnitude and duration of relief after lumbar facets medial branch nerves radiofrequency ablation: a randomized double-blinded study

IntroductionThere are numerous studies appraising the variables that may influence the clinical outcomes after lumbar thermal radiofrequency ablation (RFA). Expanding the lesion size may increase the likelihood of capturing the...

Radiofrequency thermal ablation of giant placental chorioangioma complicated with fetal hydrops: a case report and successful outcome

Abstract Objectives Chorioangiomas are the most frequently occurring type of benign tumour of the placenta. However, large chorioangiomas greater than 4 cm are rare and can be more frequently associated with serious complications such as: polyhydramnios, hydrops fetalis, fetal anaemia, intrauterine growth restriction, preterm birth, and an increased risk of perinatal mortality. Importantly timely prenatal diagnosis with close surveillance alongside potential intrauterine intervention can prove impactful on pregnancy outcome and fetal survival. Case presentation We present a case of a 36-year-old female referred to our tertiary fetal medicine unit at 28 weeks’ gestation with a large chorioangioma measuring 9.4×8.8×5.5 cm and ultrasonographic evidence of severe fetal anaemia and fetal hydrops. The patient underwent an intrauterine transfusion and in utero surgical therapy with radiofrequency ablation (RFA). Immediately following the procedure, the fetus sustained a period of bradycardia, followed by asystole. Delivery was expedited via emergency caesarean section. Careful planning and rapid delivery after fetal intervention within the most appropriate surgical setting mitigated risks for the baby and resulted in a positive outcome. The baby was discharged from the neonatal unit on day 84 of life. Conclusions Large placental chorioangiomas are a rare occurrence, however, when associated with fetal complications present a high incidence of adverse perinatal outcomes. In utero interventions require careful planning and surgical expertise to ensure improved fetal and neonatal outcomes. To the best of our knowledge this case is the first recorded instance of a successful postnatal outcome following RFA for a large placental chorioangioma, whereby the fetus was complicated by fetal hydrops.

Endoscopic Management of Gastro-Entero-Pancreatic Neuroendocrine Tumours: An Overview of Proposed Resection and Ablation Techniques.

A literature search of MEDLINE/PUBMED was conducted with the aim to highlight current endoscopic management of localised gastro-entero-pancreatic NETs. Relevant articles were identified through a manual search, and reference lists were reviewed for additional articles. The results of the research have been displayed in a narrative fashion to illustrate the actual state-of-the-art of endoscopic techniques in the treatment of NETs. Localised NETs of the stomach, duodenum and rectum can benefit from advanced endoscopic resection techniques (e.g., modified endoscopic mucosal resection, endoscopic full thickness resection, endoscopic submucosal dissection) according to centre expertise. Radiofrequency thermal ablation can be proposed as an alternative to surgery in selected patients with localised pancreatic NETs.

An anthropomorphic thyroid phantom for ultrasound-guided radiofrequency ablation of nodules.

Needle-based procedures, such as fine needle aspiration and thermal ablation, are often applied for thyroid nodule diagnosis and therapeutic purposes, respectively. With blood vessels and nerves nearby, these procedures can pose risks in damaging surrounding critical structures. The development and validation of innovative strategies to manage these risks require a test object with well-characterized physical properties. For this work, we focus on the application of ultrasound-guided thermal radiofrequency ablation. We have developed a single-use anthropomorphic phantom mimicking the thyroid and surrounding anatomical and physiological structures that are relevant to ultrasound-guided thermal ablation. The phantom was composed of a mixture of polyacrylamide, water, and egg white extract and was cast using molds in multiple steps. The thermal, acoustical, and electrical characteristics were experimentally validated. The ablation zones were analyzed via non-destructive T2 -weighted magnetic resonance imaging scans utilizing the relaxometry changes of coagulated egg albumen, and the temperature distribution was monitored using an array of fiber Bragg grating sensors. The physical properties of the phantom were verified both on ultrasound as well as in terms of the phantom response to thermal ablation. The final temperature achieved (92°C), the median percentage of the nodule ablated (82.1%), the median volume ablated outside the nodule (0.8mL), and the median number of critical structures affected (0) were quantified. An anthropomorphic phantom that can provide a realistic model for development and training in ultrasound-guided needle-based thermal interventions for thyroid nodules has been presented.

Diaphragmatic Liver Herniation after Radiofrequency Ablation of a Secondary Liver Tumor.

Radiofrequency thermal ablation (RFA) is widely used and has been accepted for the treatment of unresectable tumors. The leading technique that is used is percutaneous RFA under CT or US guidance. Multicenter surveys report acceptable morbidity and mortality rates for RFA. The mortality rate ranges from 0.1% to 0.5%, the major complication rate ranges from 2% to 3%. Diaphragmatic injury is a rare complication and it is described after RFA of subdiaphragmatic tumors. Most of them are without clinical importance. There are some case reports about diaphragmatic herniation of the intestine into the pleural cavity. We present a case of diaphragmatic perforation resulting in the herniation of the liver into the pleural cavity. A thoracotomy was performed, the liver was lowered back into the peritoneal cavity and the perforation was closed with mesh.

Comparative study between knee genicular nerve ablation by thermal radiofrequency vs thermal radiofrequency plus alcohol neurolysis for treatment of symptomatic knee osteoarthritis

Comparative study between knee genicular nerve ablation by thermal radiofrequency vs thermal radiofrequency plus alcohol neurolysis for treatment of symptomatic knee osteoarthritis

Computational Modeling of Thermal Ablation Zones in the Liver: A Systematic Review

Purpose: This systematic review aims to identify, evaluate, and summarize the findings of the literature on existing computational models for radiofrequency and microwave thermal liver ablation planning and compare their accuracy. Methods: A systematic literature search was performed in the MEDLINE and Web of Science databases. Characteristics of the computational model and validation method of the included articles were retrieved. Results: The literature search identified 780 articles, of which 35 were included. A total of 19 articles focused on simulating radiofrequency ablation (RFA) zones, and 16 focused on microwave ablation (MWA) zones. Out of the 16 articles simulating MWA, only 2 used in vivo experiments to validate their simulations. Out of the 19 articles simulating RFA, 10 articles used in vivo validation. Dice similarity coefficients describing the overlap between in vivo experiments and simulated RFA zones varied between 0.418 and 0.728, with mean surface deviations varying between 1.1 mm and 8.67 mm. Conclusion: Computational models to simulate ablation zones of MWA and RFA show considerable heterogeneity in model type and validation methods. It is currently unknown which model is most accurate and best suitable for use in clinical practice.

Pulsed Electric Field Ablation versus Radiofrequency Thermal Ablation in Murine Breast Cancer Models: Anticancer Immune Stimulation, Tumor Response, and Abscopal Effects

PurposeTo compare the immune response and survival after size-matched radiofrequency (RF) ablation and a proprietary form of pulsed electric field (PEF) ablation in murine tumors. Material and MethodsOrthotopically inoculated EMT6 or 4T1 murine tumors received sham, RF ablation, or PEF ablation. 4T1 tumor ablations included subgroups with intraperitoneal checkpoint inhibition immunotherapy (αPD-1). Blood was collected for cytokine profiling and flow cytometry. Tumor size was measured and survival was monitored. Tumor samples were processed for histology, immunohistochemistry, flow cytometry, and cytokine profiling. Lungs were collected from 4T1-bearing mice for hematoxylin and eosin histology to assess metastatic spread and abscopal effect induced by ablation. ResultsPEF elicited distinct immunomodulatory effects, with clear differences in serum and tumor cytokine profiles compared with RF ablation, including intratumoral downregulation of vascular endothelial growth factor, hypoxia-inducible factor 1α, c-MET, interleukin-10, Ki67, and tumor necrosis factor-α (all P < .05). PEF increased innate immune activation, with enhanced recruitment of dendritic cells, M1 macrophages, and natural killer cells coupled with a reduction in M2 macrophages and myeloid-derived suppressor cells (all P < .05). Concurrently, PEF strengthened adaptive immunity compared with RF ablation, characterized by increased antigen-specific T cells and decreased regulatory T cells (all P < .05). PEF stalled tumor growth and increased survival at the end of the study (≥4× versus RFA). Finally, PEF promoted an abscopal effect of clearing metastases in the lungs, which was stronger in combination with αPD-1 than with PEF alone. ConclusionsThe proprietary form of PEF used in this study evoked a preferential immunostimulatory profile versus RF ablation thermal ablation in mice, with implications for enhancing the therapeutic effectiveness of checkpoint inhibition immunotherapy for immunotherapy-unresponsive tumors.

Ultrasound Patterns of Hepatocellular Carcinoma and Their Prognostic Impact: A Retrospective Study.

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death. Abdominal ultrasound (US) is by far the most widely used first-level exam for the diagnosis of HCC. We aimed to assess whether different ultrasound patterns were related to tumor prognosis. We retrospectively reviewed all patients with a new diagnosis of HCC (single nodule) and undergoing radiofrequency thermal ablation (RFTA) at our clinic between January 2009 and December 2021. Patients were classified according to four HCC ultrasound patterns: 1A, single capsulated nodule; 1B, well capsulated intra-node nodule; 1C, cluster consisting of capsulated nodules; and 2, non-capsulated nodule. 149 patients were analysed; median follow-up time was 43 months. US patterns 1A (32.9%) and 1B (61.1%) were the most commonly seen. Median overall survival (OS) and recurrence-free survival (RFS) from RFTA were 54 months (95% CI, 42-66) and 22 months (95% CI, 12-32), respectively. Pattern 1A showed the best OS. Compared to pattern 1A, 1B was independently associated with worse OS (51 months (95% CI, 34-68) vs. 46 months (95% CI, 18-62)) and RFS (34 months (95% CI, 27-41) vs. 18 months (95% CI, 12-24)). Patterns 1C and 2 were associated with worse RFS compared to 1A, while no difference was seen for OS. Among baseline clinical variables, pattern 1B exhibited higher histological grade (p = 0.048) and tumor dimension (p = 0.034) compared to pattern 1A. Our findings demonstrate that different US patterns correlate with different survival outcomes and tumor behavior in patients with HCC. Prospective studies are needed to confirm these results.

Treatment of Plantar Fasciitis in Patients with Calcaneal Spurs: Radiofrequency Thermal Ablation or Extracorporeal Shock Wave Therapy?

We aimed to compare the effectiveness of ESWT (Extracorporeal Shock Wave Therapy) and RFA (Radiofrequency Thermal Ablation) on pain, disability, and activity limitation in the treatment of plantar fasciitis in patients with calcaneal spurs. Patients who apply to Orthopedics and Traumatology and Physical Medicine and Rehabilitation departments with a complaint of heel pain are included in this retrospective study. We included patients diagnosed with calcaneal spurs who received treatment with ESWT (n = 80) and RFA (n = 79) between 1 August 2021 and 1 September 2022. All patients were evaluated using the Visual Analog Scale (VAS), Foot Function Index (FFI), and the Roles and Maudsley score (RM) before and after treatment. An evaluation was performed on average 6 months after treatment. This study included 79 RFA patients (34 females and 45 males) with a mean age of 55.8 ± 9.6 years and 80 ESWT patients (20 females and 60 males) with a mean age of 49.1 ± 9.5 years. There was a significant decrease in VAS scores after treatment in both the RFA and ESWT groups (z: -4.98, z: -5.18, respectively, p < 0.001). The reductions in FFI pain, FFI activity restriction, FFI disability, and RM scores were significant in both groups, although the scores after treatment were lower in the RFA group. This study demonstrates that ESWT and RFA significantly reduced pain, disability, and activity restriction in the treatment of plantar fasciitis in patients with calcaneal spurs. ESWT proved particularly effective in alleviating pain, whereas RFA had more pronounced effects on reducing disability and activity limitations. The choice of treatment should be based on the patient's specific complaints.

Factors influencing recurrent varicose vein formation after radiofrequency thermal ablation for truncal reflux performed in two high-volume venous centers

ObjectiveRecanalization of the saphenous vein trunk after endovenous radiofrequency ablation (RFA) is often associated with recurrent varicose veins (RVVs) or recanalization. This study aimed to assess the long-term results of RFA of the great saphenous vein (GSV) and identify the risk factors for GSV recanalization and RVVs during follow-up for patients presenting to dedicated outpatient vein centers. MethodsAll consecutive patients with incompetent GSVs who underwent RFA between 2009 and 2019 were retrospectively analyzed. The primary study end points were freedom from GSV recanalization and the RVV rate during follow-up. The secondary study end points were the postoperative complication rate and the risk factors for GSV recanalization and RVVs. Univariate and multivariate analyses were performed to identify the potential risk factors for GSV recanalization and RVVs. ResultsDuring the study period, 1568 limbs were treated in 1300 consecutive patients (mean age, 53.5 ± 12.9 years; 71.9% women; CEAP [clinical, etiology, anatomy, pathophysiology] C2-C6; venous clinical severity score >5). Technical success was achieved in 99.7% of cases. At a mean follow-up of 57.2 ± 25.4 months, the GSV occlusion and freedom from reintervention rates were 100% and 100% within 1 week, 97% and 95.7% at 1 year, 95.2% and 93.1% at 3 years, and 92.4% and 92.8% at 5 years, respectively. The recurrence rate was 10% (n = 158) during the follow-up period. On multivariate analysis, a direct confluence of the accessory saphenous vein into the saphenofemoral junction (odds ratio [OR], 1.561; 95% confidence interval [CI], 1.0-7.04; P = .032), a history of pregnancy >2 (OR, 3.68; 95% CI, 1.19-11.36; P = .023), C4 (OR, 6.41; 95% CI, 1.36-30.28; P = .019), and preoperative GSV diameter >10 mm (OR, 1.82; 95% CI, 1.65-4.03; P = .043) were risk factors for GSV recanalization. Moreover, age >70 years (OR, 1.04; 95% CI, 1.01-1.06; P = .014) and incompetent perforator veins (OR, 1.17; 95% CI, 0.65-2.03; P = .018) were also risk factors for RVVs. ConclusionsRFA is a safe technique to ablate the GSV with a low complication rate and durability during 5 years of follow-up. However, patients with a high clinical score and those with direct confluence of the accessory saphenous vein into the saphenofemoral junction experienced higher long-term GSV recanalization and RVV rates.

Thermal Radiofrequency Ablation of the Shoulder: а Novel Technique “Palisade”

Thermal Radiofrequency Ablation of the Shoulder: а Novel Technique “Palisade”

Osteoid Osteoma of the Hand: Surgical Treatment versus CT-Guided Percutaneous Radiofrequency Thermal Ablation.

(1) Background: Osteoid osteoma (OO) is one of the most common benign bone tumors. This type of osteogenic tumor is generally characterized by a well-defined lytic area with a vascularized central nidus surrounded by sclerosis and bone thickening. The wrist and hand bones are infrequent sites for osteoid osteoma: only 10% of the cases arise in these areas. Standard treatments are surgical excision and radio-frequency ablation (RFA), both with advantages and disadvantages. This study aimed to compare the two techniques to prove if RFA could be a potential alternative to surgery in the treatment of OO of the hand. (2) Methods: Patients treated for OO of the hand between January 2011 and December 2020 were evaluated and data was collected regarding the lesions' characteristics and the treatment outcome. Each patient was followed up for 24 months and VAS pain (Visual Analogue Scale), DASH (Disability of the Arm, Shoulder and Hand), and PRWE (Patient-Related Wrist Evaluation) scores were collected. (3) Results: A total of 27 patients were included in the study: 19 surgical and 8 RFA. Both treatments showed a significant improvement in pain and functionality. Surgery was associated with a higher complication rate (stiffness and pain), while RFA was associated with a higher recurrence rate (2/8 patients). RFA allowed for a speedier return to work. (4) Conclusions: We believe that osteoid osteoma treatment with RFA in the hand should be an available alternative to surgery as it allows rapid pain relief and a swift return to work. Surgery should be reserved for cases of diagnostic uncertainty or periosteal localization.

ID: 205925 Real-World Outcomes Using Thermal Radiofrequency (TRF) Ablation for Chronic Pain

Minimally invasive interventional pain procedures, such as thermal radiofrequency (TRF) ablation, have steadily progressed to become a key segment of the therapeutic armamentarium now available to the chronic pain patient population. Here, we report real world-collected outcomes from a study of patients treated with TRF for management of chronic pain.

ID: 200009 Real-World Outcomes Using Pulsed and/or Thermal Radiofrequency for Treatment of Chronic Pain in Europe

Treating several chronic intractable pain syndromes with a diverse set of etiologies has been consistently shown to be successfully carried out using radiofrequency (RF). Conventional thermal RF (TRF) uses the application of heat (i.e., temperature) to thermo-coagulate and ablate neural tissue. Alternatively, pulsed RF (PRF) is performed using short pulses (typically 20 ms every 0 5 sec) at much lower temperatures usually no higher than 42ºC, thus avoiding destruction of neural tissue. Although these RF methods have specific advantages and disadvantages, they both offer viable alternatives for consideration per the particular aspects of the chronic pain condition as well as the overall health and preference of each patient 1 While RF is now a well-established therapeutic modality for chronic pain, periodic assessment of real-world patient data can contribute to the overall compendium of existing evidence as well as spur the initiation of new clinical studies.

Impact of the introduction of minimally invasive treatments of the thyroid (MITT) for benign thyroid nodules in an Italian hospital: a cost-minimization analysis.

Prevalence of thyroid nodules is high in the adult population, approaching 60% in women and older people. Most thyroid nodules are benign and asymptomatic. However, a not negligible part of them causes compressive symptoms and/or cosmetic concerns and need to be treated. In the last two decades, minimally-invasive treatments of the thyroid (MITT) have been proposed in routine clinical practice as a reliable cost-effective alternative to surgery in patients with symptomatic benign thyroid nodules (SBTNs). To perform a cost-minimization analysis comparing direct, indirect and intangible costs of radiofrequency (RFA) and laser thermal ablation (LTA) with traditional surgery in patients with SBTNs. Data of patients treated by MITT for SBTNs from October 1st 2019 to September 30th 2022 in a single Italian tertiary Center were analyzed. Costs were compared to those of traditional surgery reported in the 2022 Associazione Medici Endocrinologi Guidelines on the Management of SBTNs. In the study lapse, 157 MITT of SBTNs were performed in 148 patients, 114 females and 34 males (mean age: 59 yrs; median age: 57 yrs). Before MITT, the mean thyroid nodule volume was 19 ml; 1 year after MITT, volume reduction rate >50% and symptom relief were achieved in 89% and 93% of patients, respectively. No major complications occurred. Adding up pre-operative, operative and post-operative costs, total direct costs per single procedure are the following: 1361.43 € for LTA when using one optic fiber; 1761.43 € for LTA when using two optic fibers; 1968.53 € for RFA; 3338.39 € for hemithyroidectomy plus isthmectomy; 4034.99 € for total thyroidectomy. Surgery was impactful on direct-i.e., preoperative, operative and postoperative-costs, due to longer operating room occupation time and hospital stay. Overall, a total saving for the Italian National Health Service of 285,377.15 € has been obtained treating the 148 patients by MITT instead of surgery. Likewise, MITT was advantageous also for indirect costs-i.e., those related to "loss of productivity" caused by time off work due to hospital stay and recovery time-, for both the self-employed workers and the Government, the latter saving 53,838.50 € overall. Finally, intangible costs, related to patients' quality of life-e.g., residual surgical scar, stress related to general anesthesia, convalescence, and life-long intake of L-Thyroxine replacement therapy-were all in favor of MITT. This real-life cost-minimization analysis demonstrates that LTA and RFA are safe and cost-effective procedures for the treatment of SBTNs. In our 3 years experience, adding the savings of 285,377.15 € for direct costs to those of 53.838,50 € for indirect costs, in total 339,215.65 € were saved. The saving concern patients, the National Health System and the Government.

Abstract No. 7 ▪ FEATURED ABSTRACT Pulsed Electric Field (PEF) Ablation Invokes Stronger Immune Cytokine Profile and Tumor Response than Radiofrequency Thermal Ablation for Matched Ablation Volumes

Focal tumor ablation may cause secondary immunogenic upregulation that enhances local and distant tumor responses, with profiles that are unique to each modality., Pulsed electric fields (PEFs) use short duration-high voltage electrical pulses to destabilize and kill cells through various biochemical processes. Because it does not rely on thermal effects PEF does not damage interstitial proteins, fostering improved antigen integrity and immune signaling which may lead to lesion resolution. This study compared whether cell death and subsequent interstitial effects caused by PEF and radiofrequency ablation (RFA) result in differentiated primary tumor responses. Thirty female Balb/c mice, divided into sham, PEF, and RFA treatment groups (n = 10/group) were transplanted with EMT6 cells in the left mammary fat pad. Eight days after challenge (d = 0), mice in the PEF and RFA groups received treatment with doses selected to achieve similar subtotal ablation volumes. Three mice from each group were euthanized at day 4 for H&E analysis of ablation zone. The remainder were survived to 10-days post-ablation to monitor tumor growth. Serum was collected on Days -1, +1, +4 and +10 for cytokine analysis. Four-day histology demonstrated comparable subtotal ablation areas between PEF and RFA treatment. While RFA-treated tumors presented immune cells accumulating at the tumor-treatment zone boundary, PEF-treated tumors showed immune cell infiltration throughout the tumor. Further, PEF treatment slowed tumor growth compared with RFA or sham treatments, with day 10 average tumor volumes of 335, 791, and 857 mm3 for PEF, RFA, and sham group, respectively. Ingenuity Pathway Analysis (IPA) of 32 serum cytokines revealed most notable differences between groups on day 4 post-ablation. The PEF-treated group had a significant decrease in the levels of CSF1, CSF2, CSF3, CCL2, IL1β, IL6, IL13, and TNF, and an increase in the levels of IL4. These changes suggest that PEF is associated to 1) decreased accumulation of myeloid derived suppressor cells (MDSCs), 2) decreased the proliferation of tumor-associated macrophages (TAMs), 3) decreased proliferation, survival and invasion of tumor cells. Conversely, these changes were all the opposite for the RFA group. PEF treatment may cause a stronger EMT6 tumor response in mice compared with RFA treatment. These data suggest that PEF may have a greater local and distant tumor response benefit versus RFA thermal ablation. Further studies should explore potential abscopal effects.