Local Recurrence After Microwave Ablation of Lung Malignancies: A Systematic Review

Performance of an Anti-Phase Technology-Powered Microwave Ablation System on Ex Vivo Liver, Lung and Kidney: Analysis of Temperature Trend, Ablation Size and Sphericity

PURPOSE

Investigating the performance of the new Dophi™ M150E Microwave Ablation System, in terms of temperature distribution, ablation size and shape, reproducibility.

MATERIALS AND METHODS

The Dophi™ M150E Microwave Ablation System was tested on ex vivo liver, lung and kidney, at 6 different settings of time, power and number of MW antennas (single antenna: 50 and 100 W at 5 and 10 min; double antenna: 75 W at 5 and 10 min). The temperature distribution was recorded by Fiber Bragg Grating sensors, placed at different distances from the antennas. The ablation axes were measured and the sphericity index was calculated.

RESULTS

The standard deviation of ablation axes was < 5 mm, except at the highest energy and time setting for the lung. A maximum temperature rise of ~ 80 °C was measured. The measured ablation axes are overall comparable with the manufacture's values, especially at lower power and with one MW antenna (average maximum difference is 7 mm). The mean sphericity index of 0.95, 0.79 and 0.9 was obtained for the liver, lung and kidney, respectively, with a single antenna. With double antenna setup, the sphericity index was closer to 1 when 75 W for 10 min were used.

CONCLUSIONS

Dophi™ M150E allows good reproducibility of ablation axes for all cases except in the lung at the highest energy level. With one antenna, an almost spherical ablation area for the liver and kidney was obtained. Using double antenna results in more homogeneous temperature distribution within the tissue compared to single antenna.

The Value of Magnetic Resonance Imaging in Assessing Immediate Efficacy After Microwave Ablation of Lung Malignancies

PURPOSE

To investigate the imaging performance and parametric analysis of magnetic resonance imaging (MRI) immediately after microwave ablation (MWA) of lung malignancies.

MATERIALS AND METHODS

We retrospectively analyzed the MRI performance immediately after MWA of 34 cases of lung malignancies. The ablation zone parameters of lung malignancies were measured, including the long diameter (L), short diameter (S), and safety margin of the ablation zone on plain computed tomography (CT), T1-weighted imaging (T1WI), and T2-weighted imaging (T2WI) after MWA. The study calculated the tumor volume (V0), the ablation zone volume (V1), and the ratio of V0 to V1 (V%). Statistical differences between the parameters were analyzed.

RESULTS

The ablation area of the lesion exhibited central low signal and peripheral high signal on T2WI, central high signal and peripheral equal or high signal on T1WI, and circumferential enhancement in the periphery. The safety margin measured on T2WI was greater than that measured on plain CT and T1WI. On plain CT, the L, S, and V1 were smaller in the effective treatment group than in the ineffective treatment group (P<0.05). On T1WI, the V% and safety margin were greater in the effective treatment group than in the ineffective treatment group (P=0.009 and P=0.016, respectively).

CONCLUSIONS

MRI may be a new, valuable method to assess immediate efficacy after MWA for lung malignancies using the ablation zone parameters V% on T1WI and safety margin on T2WI.

Transbronchial Microwave Ablation of Peripheral Lung Tumors: The NAVABLATE Study

BACKGROUND

Image-guided thermal ablation is a minimally invasive local therapy for lung malignancies. NAVABLATE characterized the safety and performance of transbronchial microwave ablation (MWA) in the lung.

METHODS

The prospective, single-arm, 2-center NAVABLATE study (NCT03569111) evaluated transbronchial MWA in patients with histologically confirmed lung malignancies ≤30 mm in maximum diameter who were not candidates for, or who declined, both surgery and stereotactic body radiation therapy. Ablation of 1 nodule was allowed per subject. The nodule was reached with electromagnetic navigation bronchoscopy. Cone-beam computed tomography was used to verify the ablation catheter position and to evaluate the ablation zone postprocedure. The primary end point was composite adverse events related to the transbronchial MWA device through 1-month follow-up. Secondary end points included technical success (nodule reached and ablated according to the study protocol) and technique efficacy (satisfactory ablation based on 1-month follow-up imaging).

RESULTS

Thirty subjects (30 nodules; 66.7% primary lung, 33.3% oligometastatic) were enrolled from February 2019 to September 2020. The pre-procedure median nodule size was 12.5 mm (range 5 to 27 mm). Procedure-day technical success was 100% (30/30), with a mean ablative margin of 9.9±2.7 mm. One-month imaging showed 100% (30/30) technique efficacy. The composite adverse event rate related to the transbronchial MWA device through 1-month follow-up was 3.3% (1 subject, mild hemoptysis). No deaths or pneumothoraces occurred. Four subjects (13.3%) experienced grade 3 complications; none had grade 4 or 5.

CONCLUSION

Transbronchial microwave ablation is an alternative treatment modality for malignant lung nodules ≤30 mm. There were no deaths or pneumothorax. In all, 13.3% of patients developed grade 3 or above complications.

A prognostic model for predicting progression-free survival in patients with advanced non-small cell lung cancer after image-guided microwave ablation plus chemotherapy

OBJECTIVES

This study aimed to build and validate a prediction model that can predict progression-free survival (PFS) in patients with advanced non-small cell lung cancer (NSCLC) after image-guided microwave ablation (MWA) plus chemotherapy.

METHODS

Data from a previous multi-center randomized controlled trial (RCT) was used and assigned to either the training data set or the external validation data set according to the location of the centers. Potential prognostic factors were identified by multivariable analysis in the training data set and used to construct a nomogram. After bootstraps internal and external validation, the predictive performance was evaluated by concordance index (C-index), Brier Score, and calibration curves. Risk group stratification was conducted using the score calculated by the nomogram. Then a simplified scoring system was built to make risk group stratification more convenient.

RESULTS

In total, 148 patients (training data set: n = 112; external validation data set: n = 36) were enrolled for analysis. Six potential predictors were identified and entered into the nomogram, including weight loss, histology, clinical TNM stage, clinical N category, tumor location, and tumor size. The C-indexes were 0.77 (95% CI, 0.65-0.88, internal validation) and 0.64 (95% CI, 0.43-0.85, external validation). The survival curves of different risk groups also displayed significant distinction (p < 0.0001).

CONCLUSIONS

We found weight loss, histology, clinical TNM stage, clinical N category, tumor location, and tumor size were prognostic factors of progression after receiving MWA plus chemotherapy and constructed a prediction model that can predict PFS.

CLINICAL RELEVANCE STATEMENT

The nomogram and scoring system will assist physicians to predict the individualized PFS of their patients and decide whether to perform or terminate MWA and chemotherapy according to the expected benefits.

KEY POINTS

• Build and validate a prognostic model using the data from a previous randomized controlled trial to predict progression-free survival after receiving MWA plus chemotherapy. • Weight loss, histology, clinical TNM stage, clinical N category, tumor location, and tumor size were prognostic factors. • The nomogram and scoring system published by the prediction model can be used to assist physicians to make clinical decisions.

CT-based radiomics models may predict the early efficacy of microwave ablation in malignant lung tumors

PURPOSE

To establish and validate radiomics models for predicting the early efficacy (less than 3 months) of microwave ablation (MWA) in malignant lung tumors.

METHODS

The study enrolled 130 malignant lung tumor patients (72 in the training cohort, 32 in the testing cohort, and 26 in the validation cohort) treated with MWA. Post-operation CT images were analyzed. To evaluate the therapeutic effect of ablation, three models were constructed by least absolute shrinkage and selection operator and logistic regression: the tumoral radiomics (T-RO), peritumoral radiomics (P-RO), and tumoral-peritumoral radiomics (TP-RO) models. Univariate and multivariate analyses were performed to identify clinical variables and radiomics features associated with early efficacy, which were incorporated into the combined radiomics (C-RO) model. The performance of the C-RO model was evaluated by the area under the receiver operating characteristic (ROC) curve (AUC), calibration curve, and decision curve analysis (DCA). The C-RO model was used to derive the best cutoff value of ROC and to distinguish the high-risk group (Nomo-score of C-RO model below than cutoff value) from the low-risk group (Nomo-score of C-RO model higher than cutoff value) for survival analysis of patients.

RESULTS

Four radiomics features were selected from the region of interest of tumoral and peritumoral CT images, which showed good performance for evaluating prognosis and early efficacy in three cohorts. The C-RO model had the highest AUC value in all models, and the C-RO model was better than the P-RO model (AUC in training, 0.896 vs. 0.740; p = 0.036). The DCA confirmed the clinical benefit of the C-RO model. Survival analysis revealed that in the C-RO model, the low-risk group defined by best cutoff value had significantly better progression-free survival than the high-risk group (p<0.05).

CONCLUSIONS

CT-based radiomics models in malignant lung tumor patients after MWA could be useful for individualized risk classification and treatment.

Percutaneous image-guided thermal ablation of lung cancer: What is the evidence?

Thermal ablation techniques have now been used for more than twenty years in the treatment of primary lung tumours, predominantly non-small cell lung cancer (NSCLC). Although primarily used for the treatment of early-stage disease in non-surgical patients, thermal ablation is now also being used in selected patients with oligometastatic and oligoprogressive disease. This review discusses the techniques available for thermal ablation, the evidence for use of thermal ablation in primary lung tumours in early- and advanced-stage disease and compares thermal ablation to alternative treatment strategies.

Safety and Efficacy Outcomes From a Single-Center Study of Image-Guided Percutaneous Microwave Ablation for Primary and Metastatic Lung Malignancy

Introduction

Image-guided percutaneous microwave ablation (MWA) is becoming a more common treatment option for patients with primary and metastatic lung malignancies. Nevertheless, there is limited literature on the safety and efficacy of MWA compared with standard-of-care therapy, including surgical resection and radiation. This study will report the long-term outcomes after MWA for pulmonary malignancies and investigate the factors related to efficacy, including lesion size, location, and ablation power.

Methods

Retrospective single-center study analyzing 93 patients who underwent percutaneous MWA for primary or metastatic lung malignancies. Outcomes included immediate technical success, local tumor recurrence, overall survival, disease-specific survival, and complications.

Results

At a single institution, 190 lesions (81 primary and 109 metastatic) were treated in 93 patients. Immediate technical success was achieved in all cases. Freedom from local recurrence was 87.6%, 75.3%, and 69.2% and overall survival was 87.7%, 76.2%, and 74.3% at 1 year, 2 years, and 3 years, respectively. Disease-specific survival was 92.6%, 81.8%, and 81.8%. The most common complication was pneumothorax, which occurred in 54.7% (104 of 190) of procedures, with 35.2% (67 of 190) requiring a chest tube. No life-threatening complications occurred.

Conclusions

Percutaneous MWA seems safe and effective for treatment of primary and metastatic lung malignancies and should be considered for patients with limited metastatic burden and lesions less than 3 cm in size.

Issues and prospects of image-guided thermal ablation in the treatment of primary and metastatic lung tumors

The precise local minimally invasive or noninvasive treatment represents the important orientation for advancing the treatment of pulmonary malignant tumors. New local treatment methods have emerged as solutions to the shortcomings of minimally invasive or local treatment methods. Image-guided thermal ablation (IGTA) comes with the characteristics such as more accurate localization, less trauma, more definite efficacy, higher safety, stronger repeatability, fewer complications, and lower cost in treating lung tumors. This paper investigates the existing problems of IGTA in the treatment of lung tumors and puts forward the orientation of studies.

Current trends in image-guided chest interventions

Interventional radiology (IR) is a rapidly expanding medical subspecialty and refers to a range of image‐guided procedural techniques. The image guidance allows real‐time visualization and precision placement of a needle, catheter, wire and device to deep body structures through small incisions. Advantages include reduced risks, faster recovery and shorter hospital stays, lower costs and less patient discomfort. The range of chest interventional procedures keeps on expanding due to improved imaging facilities, better percutaneous assess devices and advancing ablation and embolization techniques. These advances permit procedures to be undertaken safely, simultaneously and effectively, hence escalating the role of IR in the treatment of chest disorders. This review article aims to cover the latest developments in some image‐guided techniques of the chest, including thermal ablation therapy of lung malignancy, targeted therapy of pulmonary embolism, angioplasty and stenting of mediastinal venous/superior vena cava occlusion, pulmonary arteriovenous malformation treatment and bronchial artery embolization for haemoptysis.

Microwave Ablation versus Stereotactic Body Radiotherapy for Stage I Non-Small Cell Lung Cancer: A Cost-Effectiveness Analysis

PURPOSE

To assess the cost-effectiveness of microwave ablation (MWA) and SBRT for patients with inoperable stage I non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

A literature search was performed in MEDLINE with broad search clusters. A decision-analysis model was constructed over a 5-year period. The model incorporated treatment-related complications and long-term recurrence. All clinical parameters were derived from the literature with preference to long-term prospective trials. A healthcare payers' perspective was adopted. Outcomes were measured in quality-adjusted life years (QALY) extracted from prior studies and United States dollars from Medicare reimbursements and prior studies. Base case calculations, probabilistic sensitivity analysis with 10,000 Monte Carlo simulations, and multiple one- and two-way sensitivity analyses were performed.

RESULTS

MWA yielded a health benefit of 2.31 QALY at a cost of $195,331, whereas SBRT yielded a health benefit of 2.33 QALY at a cost of $225,271. The incremental cost-effectiveness ratio was $1,480,597/QALY, indicating that MWA is the more cost-effective strategy. The conclusion remains unchanged in probabilistic sensitivity analysis with MWA being the optimal cost strategy in 99.84% simulations. One-way sensitivity analyses revealed that MWA remains cost-effective when its annual recurrence risk is below 18.4% averaged over 5 years, when the SBRT annual recurrence risk is above 1.44% averaged over 5 years, or when MWA is at least $7,500 cheaper than SBRT.

CONCLUSION

Microwave ablation appears to be a more cost-effective than stereotactic body radiotherapy for patients with inoperable stage I non-small cell lung cancer.

Drug-Eluting Bead Bronchial Arterial Chemoembolization With and Without Microwave Ablation for the Treatment of Advanced and Standard Treatment-Refractory/Ineligible Non-Small Cell Lung Cancer: A Comparative Study

Purpose

To compare the outcomes of drug-eluting bead bronchial arterial chemoembolization (DEB-BACE) with and without microwave ablation (MWA) for the treatment of advanced and standard treatment-refractory/ineligible non-small cell lung cancer (ASTRI-NSCLC).

Materials and Methods

A total of 77 ASTRI-NSCLC patients who received DEB-BACE combined with MWA (group A; n = 28) or DEB-BACE alone (group B; n = 49) were included. Clinical outcomes were compared between groups A and B. Kaplan–Meier methods were used to compare the median progression-free survival (PFS) or overall survival (OS) between the two groups. Univariate and multivariate Cox proportional hazards analyses were used to investigate the predictors of OS for ASTRI-NSCLC treated with DEB-BACE.

Results

No severe adverse event was found in both groups. Pneumothorax was the predominant MWA-related complication in group A, with an incidence rate of 32.1% (9/28). Meanwhile, no significant difference was found in DEB-BACE-related complications between groups A and B. The overall disease control rate (DCR) was 61.0% (47/77), with a significantly higher DCR in group A (85.7% vs. 46.9%, P = 0.002). The median PFS in groups A and B was 7.0 and 4.0 months, respectively, with a significant difference (P = 0.037). The median OS in groups A and B was both 8.0 months, with no significant difference (P = 0.318). The 6-month PFS and OS rates in groups A and B were 75.0% and 78.6%, 22.4% and 59.2%, respectively, while the 12-month PFS and OS rates in groups A and B were 17.9% and 28.6%, 14.3% and 22.4%, respectively. Of these, a significantly higher 6-month PFS rate was found in group A (75.0% vs. 22.4%; P < 0.001). The cycles of DEB-BACE/bronchial artery infusion chemotherapy [hazard ratio (HR): 0.363; 95% confidence interval (CI): 0.202–0.655; P = 0.001] and postoperative immunotherapy (HR: 0.219; 95% CI: 0.085–0.561; P = 0.002) were identified as the predictors of OS in ASTRI-NSCLC treated with DEB-BACE.

Conclusion

MWA sequentially combined with DEB-BACE was superior to DEB-BACE alone in the local control of ASTRI-NSCLC. Although the combination therapy reveals a trend of prolonging the OS, long-term prognosis warrants an investigation with a longer follow-up.

Update on Image-Guided Thermal Lung Ablation: Society Guidelines, Therapeutic Alternatives, and Postablation Imaging Findings

Percutaneous image-guided thermal ablation (IGTA) has been endorsed by multiple societies as a safe and effective lung-preserving treatment for primary lung cancer and metastases involving the lung and chest wall. This article reviews the role of IGTA in the care continuum of patients with thoracic neoplasms and discusses strategies to identify the optimal local therapy considering patient and tumor characteristics. The advantages and disadvantages of percutaneous thermal ablation compared to surgical resection and stereotactic body radiotherapy are summarized. Principles of radiofrequency ablation, microwave ablation, and cryoablation, as well as the emerging use of transbronchial thermal ablation, are described. Specific considerations are presented regarding the role of thermal ablation for early-stage non-small cell lung cancer (NSCLC), multifocal primary NSCLC, pulmonary metastases, salvage of recurrent NSCLC after surgery or radiation, and pain palliation for tumors involving the chest wall. Recent changes to professional society guidelines regarding the role of thermal ablation in the lung, including for treatment of oligometastatic disease, are highlighted. Finally, recommendations are provided for imaging follow-up after thermal ablation of lung tumors, accompanied by examples of expected postoperative findings and patterns of disease recurrence.

CT-guided microwave ablation in patients with lung metastases from breast cancer

Background

Computed tomography (CT)‐guided percutaneous microwave ablation (MWA) is a very common ablation method that shows a good local tumor control rate in primary and secondary lung tumors. At present, few reports have explored the safety and efficacy of MWA for lung metastases from breast cancer.

Methods

From January 2012 to January 2018, 32 breast cancer patients with 46 pulmonary metastases received CT‐guided percutaneous MWA. The study was approved by the local institutional review board. The clinical efficacy and complications of MWA were investigated.

Results

The median follow‐up time was 32 months and the main effective rate was 97.8% (45/46). Five of 46 lesions had local progression (10.9%), with a median progression time of 10 months. The 1‐, 3‐, and 5‐year overall survival (OS) rates were 96.9%, 53.3%, and 17.8%, respectively. The median OS time was 36 months. Among 46 MWA treatments, 11 (23.9%) had massive pneumothorax, two (4.3%) had massive pleural effusion, and two (4.3%) had a pulmonary infection.

Conclusion

CT‐guided percutaneous MWA may be safe and effective for treating lung metastases from breast cancer.

Current Management of Oligometastatic Lung Cancer and Future Perspectives: Results of Thermal Ablation as a Local Ablative Therapy

A growing body of evidence shows improved overall survival and progression-free survival after thermal ablation in non-small cell lung carcinoma (NSCLC) patients with a limited number of metastases, combined with chemotherapy or tyrosine kinase inhibitors or after local recurrence. Radiofrequency ablation and microwave ablation are the most evaluated modalities, and target tumor size <3 cm (and preferably <2 cm) is a key factor of technical success and efficacy. Although thermal ablation offers some advantages over surgery and radiotherapy in terms of repeatability, safety, and quality of life, optimal management of these patients requires a multidisciplinary approach, and further randomized controlled trials are required to help refine patient selection criteria. In this article, we present a comprehensive review of available thermal ablation modalities and recent results supporting their use in oligometastatic and oligoprogressive NSCLC disease along with their potential future implications in the emerging field of immunotherapy.

Local progression after computed tomography-guided microwave ablation in non-small cell lung cancer patients: prediction using a nomogram model

OBJECTIVES

To develop an effective nomogram model for predicting the local progression after computed tomography-guided microwave ablation (MWA) in non-small cell lung cancer (NSCLC) patients.

METHODS

NSCLC patients treated with MWA were randomly allocated to either the training cohort or the validation cohort (4:1). The predictors of local progression identified by univariable and multivariable analyses in the training cohort were used to develop a nomogram model. The C-statistic was used to evaluate the predictive accuracy in both the training and validation cohorts.

RESULTS

A total of 304 patients (training cohort: n = 250; validation cohort: n = 54) were included in this study. The predictors selected into the nomogram for local progression included the tumor subtypes (odds ratio [OR], 2.494; 95% confidence interval [CI], 1.415-4.396, p = 0.002), vessels ≥3 mm in direct contact with tumor (OR, 2.750; 95% CI, 1.263-5.988; p = 0.011), tumor diameter (OR, 2.252; 95% CI, 1.034-4.903; p = 0.041) and location (OR, 2.442; 95% CI, 1.201-4.965; p = 0.014). The C-statistic showed good predictive performance in both cohorts, with a C-statistic of 0.777 (95% CI, 0.707-0.848) internally and 0.712 (95% CI, 0.570-0.855) externally (training cohort and validation cohort, respectively). The optimal cutoff value for the risk of local progression was 0.39.

CONCLUSIONS

Tumor subtypes, vessels ≥3 mm in direct contact with the tumor, tumor diameter and location were predictors of local progression after MWA in NSCLC patients. The nomogram model could effectively predict the risk of local progression after MWA. Patients showing a high risk (>0.39) on the nomogram should be monitored for local progression.

Computed tomography-guided microwave ablation for the treatment of non-small cell lung cancer patients with and without adjacent lobe invasion: A comparative study

BACKGROUND

The aim of the study was to explore the outcomes of computed tomography-guided microwave ablation (MWA) in non-small cell lung cancer (NSCLC) patients with adjacent lobe invasion (ALI), and to compare the outcomes of ALI-NSCLC and non-ALI NSCLC patients after MWA.

METHODS

A total of 319 NSCLC patients and 366 tumors treated with MWA were included in the study, comprising 34 ALI-NSCLC patients and 285 non-ALI NSCLC patients. Complications, local recurrence rates, progression-free survival (PFS), and overall survival (OS) were compared. Logistic regression analyses were used to investigate the correlation between ALI and the occurrence of pneumothorax after MWA.

RESULTS

The mean tumor diameter of ablated tumors was 3.6 ± 2.2 cm. There were 95 (29.8%) NSCLC patients in which pneumothorax occurred after MWA, and all patients recovered. Of these, the ALI group had a significantly higher incidence rate of pneumothorax than the non-ALI group (52.9% vs. 27.0%, p = 0.002). The median PFS and OS for the ALI group were 12.0 ± 10.2 and 15.5 ± 9.5 months, respectively, and that of the non-ALI group were 13.0 ± 10.6 and 17.0 ± 11.1 months, respectively, and no significant difference was found in PFS (p = 0.329) nor OS (p = 0.394) between the two groups. Local recurrence rates for ALI and non-ALI groups were 29.4% and 20.7%, respectively, and no significant difference was found (p = 0.244). Logistic regression analyses revealed that ALI can increase the risk of pneumothorax (hazard ratio [HR], 2.867; p = 0.012).

CONCLUSIONS

MWA is an effective and safe approach for ALI-NSCLC treatment. Although ALI can increase the risk of pneumothorax, ALI-NSCLC patients reveal a comparable outcome to non-ALI NSCLC patients after MWA.

Society of Interventional Radiology Multidisciplinary Position Statement on Percutaneous Ablation of Non-small Cell Lung Cancer and Metastatic Disease to the Lungs: Endorsed by the Canadian Association for Interventional Radiology, the Cardiovascular and Interventional Radiological Society of Europe, and the Society of Interventional Oncology

PURPOSE

To state the Society of Interventional Radiology's position on the use of image-guided thermal ablation for the treatment of early stage non-small cell lung cancer, recurrent lung cancer, and metastatic disease to the lung.

MATERIALS AND METHODS

A multidisciplinary writing group, with expertise in treating lung cancer, conducted a comprehensive literature search to identify studies on the topic of interest. Recommendations were drafted and graded according to the updated SIR evidence grading system. A modified Delphi technique was used to achieve consensus agreement on the recommendation statements.

RESULTS

A total of 63 studies, including existing systematic reviews and meta-analysis, retrospective cohort studies, and single-arm trials were identified. The expert writing group developed and agreed on 7 recommendations on the use of image-guided thermal ablation in the lung.

CONCLUSION

SIR considers image-guided thermal ablation to be an acceptable treatment option for patients with inoperable Stage I NSCLC, those with recurrent NSCLC, as well as patients with metastatic lung disease.

Alternative methods for local ablation-interventional pulmonology: a narrative review

OBJECTIVE

To discuss and summarise the background and recent advances in the approach to bronchoscopic ablative therapies for lung cancer, focusing on focal parenchymal lesions.

BACKGROUND

This series focusses on the challenges highlighted by increasing recognition of the prognostically more favourable oligometastatic disease rather than the more frequent, but prognostically poor, high tumour burden metastatic disease. While surgery, stereotactic body radiation therapy (SBRT), and trans-thoracic percutaneous ablative techniques such as microwave (MWA) and radiofrequency ablation (RFA) are well recognised options for selected cases of pulmonary oligometastasis, bronchoscopic approaches to pulmonary tumour ablation are becoming realistic alternatives. An underlying tenet driving research and implementation in this domain is that percutaneous ablative techniques are obliged to traverse the pleura leading to a high rate of pneumothorax, and risks also goes up for peri-vascular lesions. Historically low yield bronchoscopic targeting of isolated peripheral tumors have significantly improved by incorporating multi-modality high resolution imaging and processing, including navigation planning and real-time image guidances (ultrasound, electromagnetic navigation, cone-beam CT). Combining advanced image guidance with ablative technology adaptations for bronchoscopic delivery opens up the options for high dose local ablative therapies that may reduce transthoracic complications and provide palliative to curative options for limited stage primary and oligometastatic diseases.

METHODS

We conduct a narrative review of the literature summarizing the history of bronchoscopic tumor ablation approaches, technical details including biologic rational for their uses, and current evidence for each modality, as well as investigations into future applications. Because of the relative paucity of prospective studies, we have been very inclusive in our inclusion of experiences from the published clinical databases.

CONCLUSIONS

Whilst surgical resection and SBRT remain the current mainstay of curative therapies for peripheral cancers, in the foreseeable future, developments and further research will see bronchoscopic ablative therapies become viable lung sparing alternatives in those deemed suitable. The future is bright.

A Comparative Study of Cavitary and Noncavitary Non-small Cell Lung Cancer Patients Treated with CT-Guided Microwave Ablation

PURPOSE

To explore the outcomes of computed tomography‒guided microwave (MW) ablation in patients with cavitary non-small cell lung cancer (NSCLC) and to compare the outcomes of cavitary and noncavitary NSCLC treated with MW ablation.

MATERIALS AND METHODS

A total of 317 patients with NSCLC (194 men and 123 women) treated with MW ablation were include: 19 patients with cavitary NSCLC and 298 patients with noncavitary NSCLC. Complications, progression-free survival (PFS), and overall survival (OS) were evaluated and compared between the 2 groups. The Kaplan-Meier method was used to investigate the correlation of cavity and OS in patients with NSCLC.

RESULTS

A total of 364 MW ablation procedures were performed. Adenocarcinoma was the predominant histopathological subtype in patients with cavitary NSCLC (73.7%). Cavitary NSCLC had an incidence rate of 57.9% in overall complications, which was significantly higher than that of 34.6% for noncavitary NSCLC (P = .040). In a mean follow-up of 27.2 months ± 11.9, the median PFS and OS for cavitary NSCLC were 9.0 months ± 8.5 and 14.0 months ± 10.8, respectively, and those for noncavitary NSCLC were 13.0 months ± 10.7 and 17.0 months ± 10.9, respectively. There was no significant difference in PFS (P = .180) or OS (P = .133) between cavitary and noncavitary NSCLC. In addition, the local recurrence rates for cavitary and noncavitary NSCLC were 15.8% and 21.5%, respectively, and no significant difference was found (P = .765). The Kaplan-Meier method revealed no association between the cavity and OS in patients with NSCLC treated with MW ablation.

CONCLUSIONS

MW ablation was an effective and safe approach for cavitary NSCLC treatment. Compared with noncavitary NSCLC, cavitary NSCLC manifested with more complications but a comparable outcome after MW ablation.

Is There a Role for Percutaneous Ablation for Early Stage Lung Cancer? What Is the Evidence?

PURPOSE OF REVIEW

For patients with early stage non-small-cell lung cancer (NSCLC), thermal ablation (TA) has become in the least two decades an option of treatment used worldwide for patients with comorbidities who are not surgical candidates. Here, we review data published with different TA techniques: radiofrequency ablation (RFA), microwave ablation (MWA) and cryoablation. This paper reviews also the comparison that has been made between TA and stereotactic radiotherapy (SBRT).

RECENT FINDINGS

A majority of retrospective studies, the absence of comparative studies, and the variety of techniques make difficult to get evident data. Nevertheless, these stand-alone techniques have demonstrated local efficacy for tumors less than 3 cm and good tolerance on fragile patients. Many recent reviews and database analyses show that outcomes after TA (mainly RFA and MWA) are comparable to SBRT in terms of survival rates. For patients who are unfit for surgery, TA has demonstrated interesting results for safety, benefits in overall survival, and acceptable local control.

Outcomes Following Percutaneous Microwave and Cryoablation of Lung Metastases from Adenoid Cystic Carcinoma of the Head and Neck: A Bi-Institutional Retrospective Cohort Study

OBECTIVE

The aim of this study was to report outcomes following percutaneous microwave and cryoablation of lung metastases from adenoid cystic carcinoma (ACC) of the head and neck.

MATERIAL AND METHODS

This bi-institutional retrospective cohort study included 10 patients (6 females, median age 59 years [range 28-81]) who underwent 32 percutaneous ablation sessions (21 cryoablation, 11 microwave) of 60 lung metastases (median 3.5 tumors per patient [range 1-16]) from 2007 to 2019. Median tumor diameter was 16 mm [range 7-40], significantly larger for cryoablation (22 mm, p = 0.002). A median of two tumors were treated per session [range 1-7]. Technical success, local control, complications, and overall survival were assessed.

RESULTS

Primary technical success was achieved for 55/60 tumors (91.7%). Median follow-up was 40.6 months (clinical) and 32.5 months (imaging, per tumor). Local control at 1, 2, and 3 years was 94.7%, 80.8%, and 76.4%, respectively, and did not differ between ablation modalities. Five of fifteen recurrent tumors underwent repeat ablation, and secondary technical success was achieved in four (80%). Assisted local tumor control at 1, 2, and 3 years was 96.2%, 89.8%, and 84.9%, respectively. Complications occurred following 24/32 sessions (75.0%) and 57.2% Common Terminology Criteria for Adverse Events (CTCAE) lower than grade 3. Of 13 pneumothoraces, 7 required chest tube placements. Hemoptysis occurred after 7/21 cryoablation sessions, and bronchopleural fistula developed more frequently with microwave (p = 0.037). Median length of hospital stay was 1 day [range 0-10], and median overall survival was 81.5 months (IQR 40.4-93.1).

CONCLUSION

Percutaneous computed tomography-guided microwave and cryoablation can treat lung metastases from ACC of the head and neck. Complications are common but manageable, with full recovery expected.

Effect of changes in lung physical properties on microwave ablation zone during respiration

Microwave ablation is a promising minimally invasive treatment for cancer. However, due to the respiratory movement of the lungs, it is very difficult to accurately predict and control the microwave ablation zone. Therefore, the influence of the changes of the physical parameters of the respiratory process on the microwave ablation zone is studied. Firstly, based on the 4D-CT describing the respiratory process of the lungs, all the image data are from 100 non-small cell lung cancer radiotherapy patients (50 males and 50 females, average 58 years, range 55-61 years). According to the theory of porous media, the change of the effective thermal conductivity of the lung tissue during the breathing process is obtained. The effective thermal conductivity of the lung parenchyma during respiration varies from 0.16 to 0.20 W/m °C, with the lowest vale at the end of inspiration and the highest at the end of expiration. The transient problems during microwave ablation of pulmonary tissue are analyzed by finite element method. The changes of relative permittivity, conductivity and density changes during the breathing process are also considered. The results show that the microwave ablation zone is significantly larger under dynamic physical parameters. At the end of expiration, when the tissue parameter is set to constant, the ablation lesion area is more concentrated around the tip and slot of the antenna, and the backward heating effect is smaller, Ablation volume was superior in nonventilated lungs. Therefore, single-lung ventilation can be considered during pulmonary ablation to reduce the impact of breathing on the ablation area. These findings can be useful to further our understanding the MWA and hold promise towards achieving successful treatment objective as well as enhanced therapeutic output via improved treatment planning and strategy. This study provides the basis for clinical pulmonary ablation and can also be used as a preoperative plan to provide guidance to physicians.

Successful management of diaphragmatic ectopic pregnancy using ultrasound-guided percutaneous microwave ablation

Diaphragmatic ectopic pregnancy is a rare status during the perinatal period. We reported that a 24-year-old woman with diaphragmatic ectopic pregnancy successfully received ultrasound-guided percutaneous microwave ablation. It found that beta-human chorionic gonadotropin level decreased showing 1067, 311.3 and 118.4 mIU/mL within five postoperative days, and P level reduced from 3.64 to 1.59 nmol/L. Contrast-enhanced ultrasonography image on the third day after ablation indicated that there was no enhancement in the lesion. This case indicated that ultrasound-guided percutaneous microwave ablation could be critical for a good outcome in diaphragmatic ectopic pregnancy.