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

Potential of Thermal Ablation Combined with Immunotherapy in Peripheral Lung Tumors: A Review and Prospect

BACKGROUND

Lung tumors are prevalent malignancies associated with a high mortality rate, imposing significant medical and societal burdens. Although immunotherapy shows promise in improving survival, response rates are relatively modest. Thermal ablation can not only eliminate tumor cells directly but also enhance antitumor immunity response, thus manifesting a remarkable propensity to synergize with immunotherapy.

SUMMARY

In this review, we provided a brief overview of the application of thermal ablation in peripheral lung tumors. We summarized the patient selection of thermal ablation. We highlighted the potential of thermal ablation to augment the antitumor immune response, offering a promising avenue for combined therapies. We summarized studies assessing the synergistic effects of thermal ablation and immunotherapy in preclinical and clinical settings. Lastly, we underscored the urgent issues that warrant in-depth exploration when applying thermal ablation and immunotherapy to lung tumor patients.

KEY MESSAGES

This review emphasized the prospects of using thermal ablation combined with immunotherapy in patients with peripheral lung tumors. However, further research is needed to enhance and optimize this treatment strategy.

Safety and local efficacy of computed tomography-guided microwave ablation for treating early-stage non-small cell lung cancer adjacent to bronchovascular bundles

OBJECTIVES

To retrospectively evaluate the safety and efficacy of computed tomography (CT)-guided percutaneous microwave ablation in treating early-stage non-small cell lung cancer (NSCLC) adjacent to bronchovascular bundles.

METHODS

Two hundred and thirty-one patients with early-stage NSCLC who underwent CT-guided microwave ablation of the tumor were included for analysis. Among these, 66 lesions were located adjacent to the bronchovascular bundle. Achievement of the specific ablation range (defined as the ablation zone encompassing the tumor and the adjacent vessel) was assessed after ablation. Complications and tumor progression after treatment were examined and compared between the bronchovascular bundle and non-bronchovascular bundle groups.

RESULTS

A total of 231 patients were included. Overall, 1-, 2-, and 3-year local progression-free survival (LPFS) was 77.4%, 70.5%, and 63.8%, respectively. Bronchovascular bundle proximity, pure-solid tumor, tumor size, and ablation margin < 5 mm were independent risk factors for local progression in multivariate analysis. In the bronchovascular bundle group, the 1-, 2- and 3-year LPFS rates were 63.0%, 50.7%, and 43.4%, respectively; vessel proximity and specific ablation range failure were independent risk factors for local progression. Overall survival in the entire cohort was 93.0% at 1 year, 76.1% at 2 years, and 55.0% at 3 years. The incidence of postoperative complications did not significantly differ between the two groups (p > 0.05). The most common complication was pneumothorax. Severe hemoptysis did not occur.

CONCLUSION

Tumor location near the bronchovascular bundles was a significant risk factor for local progression after microwave ablation. Achieving a specific ablation range may increase LPFS for these lesions.

CLINICAL RELEVANCE STATEMENT

Achieving the specific ablation range may improve local efficacy for early-stage non-small cell lung cancer located adjacent to the bronchovascular bundle.

KEY POINTS

• Local efficacy of percutaneous microwave ablation in treating early-stage non-small cell lung cancer was affected by bronchovascular bundle proximity. • Achieving the specific ablation range may improve local efficacy for lesions located adjacent to the bronchovascular bundle.

Potential biomarkers for predicting immune response and outcomes in lung cancer patients undergoing thermal ablation

Thermal ablation is a promising alternative treatment for lung cancer. It disintegrates cancer cells and releases antigens, followed by the remodeling of local tumor immune microenvironment and the activation of anti-tumor immune responses, enhancing the overall effectiveness of the treatment. Biomarkers can offer insights into the patient's immune response and outcomes, such as local tumor control, recurrence, overall survival, and progression-free survival. Identifying and validating such biomarkers can significantly impact clinical decision-making, leading to personalized treatment strategies and improved patient outcomes. This review provides a comprehensive overview of the current state of research on potential biomarkers for predicting immune response and outcomes in lung cancer patients undergoing thermal ablation, including their potential role in lung cancer management, and the challenges and future directions.

Cryoablation is superior to radiofrequency ablation for the treatment of non-small cell lung cancer: A meta-analysis

This meta-analytical study compared the efficacy of cryoablation and radiofrequency ablation (RFA) in treating non-small cell lung cancer (NSCLC). We searched PubMed, Cochrane, Embase, and Web of Science™ for all relevant articles published until April 2022 that compared the efficacy of RFA and cryoablation in treating NSCLC. We used the Cochrane evaluation tool to assess the risk of bias. The fixed- or random-effects models were used, when appropriate. The primary outcome was a 3-year disease-free survival, whereas recurrence rate and complication rates were secondary outcomes. There were 340 patients divided across the seven studies we included in our meta-analysis. Based on the continuous-type variable analysis, cryoablation was superior to RFA in terms of 3-year disease-free survival (P = 0.003) and complication (P ＜ 0.00001) rates. Similarly, significant reductions in cryoablation were found for recurrence rates (P = 0.05) compared with RFA. Overall, cryoablation was superior to RFA in terms of prognosis and lifespan, regardless of whether systemic metastases occurred in non-small cell lung cancer.

Percutaneous microwave ablation for lung tumors: a retrospective case-control study of conventional CT and C-arm CT guidance

Background

Although conventional computed tomography (cCT) is the mainstream guidance equipment for lung microwave ablation (MWA), C-arm CT can provide 3-dimensional (3D) CT-like images reconstructed from 2-dimensional (2D) digital subtraction angiography (DSA) information within 8 seconds, highlighting its utility as a new guidance tool. This retrospective case-control study was performed to evaluate the clinical performance of percutaneous MWA for lung tumors using cCT and C-arm CT guidance.

Methods

From April 2015 to April 2020, 101 consecutive patients with solitary lung tumors who underwent percutaneous MWA at our single center (Zhengzhou, China) were divided into 2 groups: the cCT group (n=56), with unarmed puncture, and the C-arm CT group (n=45), with iGuide navigation-assisted puncture. The primary endpoints were technical success, technical efficacy, puncture scoring (PS), and complete ablation (CA) rate. The secondary endpoints were complications, median progression-free survival (mPFS), and median overall survival (mOS).

Results

The technical success rates were 100% in both the C-arm CT group and cCT group. The technical efficacies were 93.3% and 91.1% in the C-arm CT group and cCT group, respectively, with no statistical difference (P=0.67). The PS (2.9 vs. 2.5, P=0.02), total procedure time (TPT; 39.3 vs. 50.0 min, P<0.001), puncture time (PT; 12.6 vs. 15.7 min, P=0.001), and irradiation effective dose (ED; 15.2 vs. 20.9 mSV, P<0.001) showed significances between patients in the C-arm CT and those in the cCT group. The ablation time (AT; 9.1 vs. 9.6 min, P=0.36), CA rate (93.3% vs. 92.9%, P=0.93), local tumor progression (LTP) rate (11.1% vs. 8.9%, P=0.98), complications, mPFS (9.5 vs. 10.1 months, P=0.52), and mOS (37.9 vs. 38.8 months, P=0.67) showed no statistically significant difference between the 2 groups.

Conclusions

C-arm CT guidance is as feasible and effective as cCT for lung tumor MWA, which can increase PS and decrease TPT.

Image-guided thermal ablation for patients with epidermal growth factor receptor-mutant nonsmall cell lung cancer

Nonsmall cell lung cancer (NSCLC) is treated by various therapies such as surgical intervention, radiotherapy, chemotherapy, molecular targeted therapy, and immunotherapy. Currently, molecular targeted therapy, including epidermal growth factor receptor (EGFR) inhibitors and Anaplastic Lymphoma Kinase (ALK) and Kirsten Rat Sarcoma viral Oncogene (KRAS) inhibitors, has received much attention and improved the prognosis of NSCLC. Nevertheless, the terminal point of molecular targeted drugs is resistance. Drug resistance has been classified into oligoprogression and extensive progression based on the tumor lesion progression after drug resistance. There is extensive research demonstrating that local therapy (surgical resection, radiotherapy, and thermal ablation) can prolong the survival of patients with drug resistance. This review is intended to determine the efficacy of image-guided thermal ablation in patients with NSCLC with EGFR mutation.

Role of radiation in oligometastases and oligoprogression in metastatic non-small cell lung cancer: consensus and controversy

INTRODUCTION

The oligometastatic state in non-small cell lung cancer (NSCLC) has recently become well-established. However, the specific definition of oligometastases remains unclear. Several smaller randomized studies have investigated the safety and efficacy of radiation as metastasis-directed therapy (MDT) in oligometastatic NSCLC, which have led the way to larger studies currently accruing patients globally.

AREAS COVERED

This review covers the definitions of 'oligometastases' and explains why the oligometastatic state is becoming increasingly relevant in metastatic NSCLC. This includes the rationale for MDT in oligometastatic NSCLC, specifically reviewing stereotactic body radiation therapy (SBRT) as a treatment strategy. This review details many randomized trials that support radiation as MDT and introduces trials that are currently accruing patients. Finally, it explores some of the controversies that warrant further investigation.

EXPERT OPINION

Radiation treatment, specifically SBRT, has been shown to be safe, convenient, and cost-effective as MDT. As systemic therapy, including targeted agents and immunotherapy, continues to improve, the precise role(s) and timing of radiation therapy may evolve. However, radiation therapy as MDT will continue to be an integral part of treatment in patients with oligometastatic NSCLC.

The consideration of surgery on primary lesion of advanced non-small cell lung cancer

BACKGROUND

Numerous reports have shown that medical treatment confers excellent survival benefits to patients with advanced stage IV non-small cell lung cancer (NSCLC). However, the implications of surgery for primary lesions as palliative treatment remain inconclusive.

METHODS

We retrospectively extracted clinical data from the Surveillance, Epidemiology, and End Results Program (SEER) database and selected patients with stage IV NSCLC. Patients were classified into non-surgery and surgery groups, and propensity score matching (PSM) analysis was performed to balance the baseline information. Patients in the surgery group, whose overall survival (OS) was longer than the median survival time of those in the non-surgery group, were deemed to benefit from surgery. We evaluated the efficacy of three surgical techniques, namely, local destruction, sub-lobectomy, and lobectomy, on the primary site in the beneficial population.

RESULTS

The results of Cox regression analyses revealed that surgery was an independent risk factor for both OS (hazard ratio [HR]: 0.441; confidence interval [CI]: 0.426-0.456; P < 0.001) and cancer-specific survival (CSS) (HR: 0397; CI: 0.380-0.414; P < 0.001). Notably, patients who underwent surgery had a better prognosis than those who did not (OS: P < 0.001; CSS: P < 0.001). Moreover, local destruction and sub-lobectomy significantly compromised survival compared to lobectomy in the beneficial group (P < 0.001). After PSM, patients with stage IV disease who underwent lobectomy needed routine mediastinal lymph node clearing (OS: P = 0.0038; CSS: P = 0.039).

CONCLUSION

Based on these findings, we recommend that patients with stage IV NSCLC undergo palliative surgery for the primary site and that lobectomy plus lymph node resection should be conventionally performed on those who can tolerate the surgery.

The CXCL10/CXCR3 Pathway Contributes to the Synergy of Thermal Ablation and PD-1 Blockade Therapy against Tumors

As a practical local therapeutic approach to destroy tumor tissue, thermal ablation can activate tumor-specific T cells via enhancing tumor antigen presentation to the immune system. In the present study, we investigated changes in infiltrating immune cells in tumor tissues from the non-radiofrequency ablation (RFA) side by analyzing single-cell RNA sequencing (scRNA-seq) data of tumor-bearing mice compared with control tumors. We showed that ablation treatment could increase the proportion of CD8⁺T cells and the interaction between macrophages and T cells was altered. Another thermal ablation treatment, microwave ablation (MWA), increased the enrichment of signaling pathways for chemotaxis and chemokine response and was associated with the chemokine CXCL10. In addition, the immune checkpoint PD-1 was especially up-regulated in the infiltrating T cells of tumors on the non-ablation side after thermal ablation treatment. Combination therapy of ablation and PD-1 blockade had a synergistic anti-tumor effect. Furthermore, we found that the CXCL10/CXCR3 axis contributed to the therapeutic efficacy of ablation combined with anti-PD-1 therapy, and activation of the CXCL10/CXCR3 signaling pathway might improve the synergistic effect of this combination treatment against solid tumors.

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.

Early enlarging cavitation after percutaneous microwave ablation of primary lung cancer

PURPOSE

This retrospective study assessed the incidence rate, risk factors, and clinical course of early enlarging cavitation after percutaneous microwave ablation (MWA) of primary lung cancer (PLC).

METHODS

This study included 557 lesions of 514 patients with PLC who underwent CT-guided percutaneous MWA between 1 January 2018 and 31 December 2021. Of these patients, 29 developed early enlarging cavitation and were enrolled in the cavity group, and 173 were randomly enrolled in the control group. Early enlarging cavitation of the lung was defined as the development of a cavity ≥30 mm within 7 days after MWA.

RESULTS

Overall, 31 (5.57%, 31/557 tumors) early enlarging cavitations occurred at an average of 5.83 ± 1.55 d after MWA. The risk factors were lesion contact with a large vessel (diameter ≥3 mm), lesion contact with the bronchus (diameter ≥2 mm), and a large ablated parenchymal volume. The cavity group had a higher incidence rate of delayed hydropneumothorax (12.9%) and bronchopleural fistula (9.68%) than the control group, resulting in a longer hospitalization (9.09 ± 5.26 days). Until Dec 31, 2022, 27 cavities disappeared after a mean of 217.88 ± 78.57 d (range, 111-510 d), two persisted, and two were lost to follow-up.

CONCLUSIONS

Early enlarging cavitation occurred in 5.57% PLC cases that underwent MWA, causing serve complications and longer hospitalization. The risk factors were ablated lesion contact with large vessels and bronchi, as well as a larger ablated parenchymal volume.

Image-Guided Percutaneous and Transarterial Therapies for Primary and Metastatic Lung Cancer

Lung cancer is the leading cause of cancer mortality in the world. A significant proportion of patients with lung cancer are not candidates for surgery and must resort to other treatment alternatives. Rapid technological advancements in fields like interventional radiology have paved the way for valid treatment modalities like image-guided percutaneous and transarterial therapies for treatment of both primary and metastatic lung cancer. The rationale of ablative therapies relies on the fact that focused delivery of energy induces tumor destruction and pathological necrosis. Image-guided percutaneous thermal ablation therapies are established techniques in the local treatment of hepatic, renal, bone, thyroid, or uterine lesions. In the lung, the 3 main indications for lung ablation include local curative intent, a strategy to achieve a chemoholiday in oligometastatic disease, and recently, oligoprogressive disease. Transarterial therapies include a set of catheter-based treatments that involve delivering embolic and/or chemotherapeutic agents directed into the target tumor via the supplying arteries. This article provides a comprehensive review of the various techniques available and discusses their applications and associated complications in primary and metastatic lung cancer.

Thermal ablation versus radiotherapy for inoperable stage III non-small cell lung cancer: a propensity score matching analysis

OBJECTIVE

To compare the survival benefits of thermal ablation (TA) and radiotherapy in inoperable patients with stage III non-small cell lung cancer (NSCLC).

METHOD

A retrospective analysis was conducted using the data from the Surveillance, Epidemiology, and End Results (SEER) program. Propensity score matching (PSM) was conducted to balance potential baseline confounding factors. Survival analyses were conducted using Kaplan-Meier and Cox regression methods.

RESULTS

The present study included 33,393 inoperable patients with stage III NSCLC, including 106 patients treated with TA and 33,287 patients treated with radiotherapy. No statistical difference in overall survival (OS) (p = .065) or cancer-specific survival (CSS) (p = .996) was found between the patients treated with TA and those treated with radiotherapy. Using 1:3 matching, a matched cohort of 420 patients (105 patients treated with TA, 315 patients treated with radiotherapy) was identified. The differences in OS (p = .177) and CSS (p = .605) were still not significant between the radiotherapy and TA groups after PSM. According to subgroup analyses, TA showed comparable survival benefits in almost all subgroups compared to radiotherapy.

CONCLUSION

For inoperable stage III NSCLC, the survival benefit of TA was comparable to radiotherapy. TA may be a potential therapeutic modality for inoperable stage III NSCLC.

Cryoablation and immune synergistic effect for lung cancer: A review

The preferred treatment for lung cancer is surgical resection, but a large number of patients are not suitable for surgical resection in clinic. CT-guided cryoablation and immunotherapy can play an important role in patients with advanced lung cancer who are ineligible for surgery. CT-guided cryoablation has been widely used in the clinical treatment of lung tumors due to its advantages of less trauma, fewer complications, significant efficacy and rapid recovery. Cryoablation can not only cause tumor necrosis and apoptosis, but also promote the release of tumor-derived autoantigens into the blood circulation, and stimulate the host immune system to produce a good anti-tumor immune effect against primary and metastatic tumors. Since the study of immune checkpoint inhibitors has proved that lung cancer can be an immunotherapeutic response disease, the relationship between cryoablation and immunotherapy of lung cancer has been paid more attention. Therefore, we reviewed the literature on cryoablation for lung cancer, as well as the research progress of cryoablation combined with immunotherapy.

Recent Perspectives on the Mechanism of Recurrence After Ablation of Hepatocellular Carcinoma: A Mini-Review

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. Hepatectomy, liver transplantation, and ablation are the three radical treatments for early-stage hepatocellular carcinoma (ESHCC), but not all patients are fit for or can tolerate surgery; moreover, liver donors are limited. Therefore, ablation plays an important role in the treatment of ESHCC. However, some studies have shown that ablation has a higher local recurrence (LR) rate than hepatectomy and liver transplantation. The specific mechanism is unknown. The latest perspectives on the mechanism of recurrence after ablation of HCC were described and summarized. In this review, we discussed the possible mechanisms of recurrence after ablation of HCC, including epithelial–mesenchymal transition (EMT), activating autophagy, changes in non-coding RNA, and changes in the tumor microenvironment. A systematic and comprehensive understanding of the mechanism will contribute to the research and development of related treatment, combined with ablation to improve the therapeutic effect in patients with ESHCC.

Assessing long-term locoregional control of spinal osseous metastases after microwave ablation

Osseous metastases to the spine result in significant pain and decreased quality of life. The purpose of this study was to evaluate the long-term efficacy of microwave ablation (MWA) for the treatment of spinal metastases regarding pain reduction and local control of disease progression. In this single center retrospective study, patients with osseous metastases to the spine undergoing MWA with vertebroplasty from 2013 to 2020 were included. Locoregional control of metabolic activity at the treated level was assessed using PET/CT scan both pre- and post-procedure. Pain reduction was measured using change in visual analog scale (VAS) pain score. Forty-eight spinal levels were treated with MWA in 28 patients (57 % male, mean age 68 ± 9 years). Median ablation time, energy, and temperature were 4 min and 13 s, 3.6 kJ, and 80 °C, respectively. Median pre-procedure maximum standard uptake value (SUVmax) was significantly reduced following ablation, from 4.55 (IQR 3.65-6.1) to 0 (IQR 0-1.8; p < 0.001), over an average of 29 ± 14.1 month follow up period. Pre-procedure VAS pain score was reduced from median (IQR) of 8 (6.5-9) to 1(1-2), 2(1-3) and 1(0.5-3) at 24 h, four weeks, and six months post-procedure, respectively (all p < 0.001 with respect to pre-procedure scores). In conclusion, this study supports microwave ablation as an effective technique for pain palliation and long-term locoregional tumor control of oligometastatic spinal disease as assessed by metabolic response.

Long-term outcome following microwave ablation of lung metastases from colorectal cancer

Purpose

To retrospectively evaluate the safety and efficacy of percutaneous computed tomography (CT)-guided microwave ablation (MWA) in colorectal cancer (CRC) lung metastases, and to analyze prognostic factors.

Materials and methods

Data were collected from 31 patients with CRC lung metastases from May 2013 to September 2017. They had removed the CRC, no extrapulmonary metastases, no more than three metastases in the lung, the maximum diameter of the lesions was ≤3 cm, and all the lung metastases could be completely ablated. The ablation procedures were performed using a KY-2000 microwave multifunctional therapeutic apparatus. Efficacy is assessed two to four weeks after ablation, and follow-up are performed every three months for two years. The primary outcome was overall survival (OS). The secondary outcomes were progression-free survival (PFS), and complications. Cox regression analysis was used for the evaluation of the statistical significance of factors affecting the end result of MWA therapy. The Kaplan–Meier method was used for estimation of survival rates.

Results

A total of 45 metastatic lung lesions from CRC in 31 patients were treated with CT-guided MWA procedures. The median OS was 76 months. The one, two, three, and five-year survival rates were 93.5%, 80.6%, 61.3%, and 51.6%, respectively. Multivariate analysis showed that the primary tumor from the rectum (P = 0.009) and liver metastases at the diagnosis of lung metastases (P = 0.043) were risk factors affecting OS, while PFS was a protective factor. The median PFS was 13 months. The maximum diameter of lung metastases lesions (P = 0.004) was a risk factor. The interval between pulmonary metastases and MWA (P=0.031) was the protective factor. Pneumothorax was observed in 13 out of 36 procedures. Four patients developed pneumothorax requiring drainage tube insertion. No patient deaths occurred within 30 days of ablation. Three out of 31 patients (9.67%) were found to have local recurrence of the original lung metastatic ablation foci.

Conclusion

MWA therapy may be safely and effectively used as a therapeutic tool for the treatment of selected CRC pulmonary metastases, and the prognosis is better in patients without liver metastases at the diagnosis of lung metastases.

Efficacy and safety of ultrasound-guided microwave ablation versus surgical resection for Bethesda category IV thyroid nodules: A retrospective comparative study

OBJECTIVE

The objective of this study was to assess the efficacy and safety of ultrasound-guided microwave ablation (MWA) for Bethesda IV thyroid nodules and to compare the outcomes, complications, and costs of MWA and thyroidectomy.

METHODS

A total of 130 patients with Bethesda IV nodules were retrospectively reviewed, involving 46 in the MWA group and 84 in the surgery group. The local institutional review board approved this study. Patients in the MWA group were followed up at 1, 3, 6, and 12 months after the intervention. Postoperative complications, treatment time, and cost in the two groups were compared.

RESULTS

Among 84 patients with 85 Bethesda IV nodules in the surgery group, postoperative pathology was benign lesions, borderline tumors, papillary thyroid carcinoma, follicular variant papillary thyroid carcinoma, follicular thyroid carcinoma, and medullary carcinoma in 44, 4, 27, 6, 3, and 1 cases, respectively. Malignant thyroid nodules were more prone to solid echostructure (86.11% vs. 72.72%), hypoechogenicity (55.56% vs. 13.63%), and irregular margin (47.22% vs. 13.63%) than benign lesions. The nodule volume reduction rate of patients at 12 months after MWA was 85.01% ± 10.86%. Recurrence and lymphatic and distant metastases were not reported during the follow-up period. The incidence of complications, treatment time, hospitalization time, incision length, and cost were significantly lower in the MWA group than in the surgery group (all p < 0.001).

CONCLUSIONS

MWA significantly reduces the volume of Bethesda IV nodules with high safety and is recommended for those with surgical contraindications or those who refuse surgical resection. Patients with suspicious ultrasound features for malignancy should be actively treated with surgery.