Thermal ablation of malignant lung tumors

Feasibility and Safety of Radiofrequency Ablation Guided by Bronchoscopic Transparenchymal Nodule Access in Canines

BACKGROUND

The treatment of pulmonary malignancies remains a challenge. The efficacy and safety of bronchoscopic radiofrequency ablation (RFA) for the treatment of lung cancer are not well elucidated.

OBJECTIVE

This study aimed to evaluate the feasibility and safety of RFA guided by bronchoscopic transparenchymal nodule access (BTPNA) in vivo.

METHODS

In an attempt to determine the parameters of RFA, we first performed RFA in conjunction with automatic saline microperfusion in the lung in vitro with various ablation energy (10, 15, 20, 25, and 30 W) and ablation times (3, 5, 8, and 10 min). The correlation between ablated area and RFA parameter was recorded and analyzed. Further, we conducted a canine study with RFA by BTPNA in vivo, observing the ablation effect and morphological changes in the lung assessed by chest CT and histopathologic examination at various follow-up time points (1 day, n = 3; 30 days, n = 4; 90 days, n = 4). The related complications were also observed and recorded.

RESULTS

More ablation energy, but not ablation time, induced a greater range of ablation area in the lung. Ablation energy applied with 15 W for 3 min served as the appropriate setting for pulmonary lesions ≤1 cm. RFA guided by BTPNA was performed in 11 canines with 100% success rate. Inflammation, congestion, and coagulation necrosis were observed after ablation, which could be repaired within 7 days; subsequently, granulation and fibrotic scar tissue developed after 30 days. No procedure-related complication occurred during the operation or in the follow-up periods.

CONCLUSION

The novel RFA system and catheter in conjunction with automatic saline microperfusion present a safe and feasible modality in pulmonary parenchyma. RFA guided by BTPNA appears to be well established with an acceptable tolerance; it might further provide therapeutic benefit in pulmonary malignancies.

Clinical Application of CT-Guided Percutaneous Microwave Ablation for the Treatment of Lung Metastasis from Colorectal Cancer

Objective

The aim of our research is to explore the clinical efficacy and safety of CT-guided percutaneous microwave ablation (MWA) for the treatment of lung metastasis from colorectal cancer.

Materials and Methods

CT-guided percutaneous MWA was performed in 22 patients (male 14, female 8, mean age: 56.05 ± 12.32 years) with a total of 36 lung metastatic lesions from colorectal cancer between February 2014 and May 2017. Clinical data were retrospectively analyzed with respect to the efficacy, safety, and outcome.

Results

Of the 36 lesions, 34 lesions (94.4%) reduced obviously with small cavitations or fibrous stripes formed and had no evidence of recurrence during follow-up. The volume of the other 2 lesions demonstrated local progression after 6 months by follow-up CT. The primary complications included pneumothorax (28%), chest pain (21%), and fever (5%). These symptoms and signs were obviously relieved or disappeared after several-day conservative treatment. The mean follow-up of the patients was 25.54 ± 12.58 months (range 2-41 months). The estimated progression-free survival rate was 94.4%.

Conclusion

Our results demonstrate that CT-guided percutaneous MWA appears to be an effective, reliable, and minimally invasive method for the treatment of lung metastasis from colorectal cancer. This trial is registered with ChiCTR-ORC-17012904.

Microwave ablation versus radiofrequency ablation for the treatment of pulmonary tumors

To retrospectively compare the efficacy and safety of radiofrequency ablation (RFA) and microwave ablation (MWA) in the treatment of pulmonary tumors, a total of 75 patients with lung tumor who underwent thermal ablation therapy in Guangdong General Hospital into the study from March 2007 to December 2014 were enrolled. Of the patients, 43 received radiofrequency ablation and 32 received microwaves ablation. The response rates, overall survival (OS), and complications rates between the RFA group and MWA group were compared. There were no significant differences in the baseline characteristics between two groups. The overall response rates of in RFA and MWA groups were 79% (34/43) and 69% (22/32), respectively, and there was no statistically significant difference between two groups (P = 0.309). The 1-, 2-, 3-, 5-year overall survival (OS) rates in RFA group and MWA group were 77%, 55%, 42%, 34% and 75%, 44%, 40%, 27%, respectively. No significant differences were found in the OS rates between two groups (P = 0.653). The complication rates were 49% (21/43) in RFA group and 50% (16/32) in MWA group; there was no significant difference between two groups (P = 0.921). No patients died during the perioperative period. Our study shows that no significant differences exist in efficacy and safety between RFA and MWA for the treatment of pulmonary tumors, which indicates that MWA could be a substitute therapy for RFA in terms of effectiveness and safety for treating pulmonary tumors.

Clinical analysis on 113 patients with lung cancer treated by percutaneous CT-guided microwave ablation

BACKGROUND

Lung Cancer is a primary tumor with poor prognosis. For early stage lung cancer, treatment options include surgical resection and microwave techniques. Percutaneous ablative techniques emerged as best therapeutic options for nonsurgical patients.

METHODS

The aim of this study was to retrospectively analyze the clinical effect of CT-guided microwave ablation (MWA) treatment for patients with lung cancer who were not eligible for surgical resection. MWA was used to treat the tumor lesion of 113 patients with lung cancer who were in our hospital from Jan, 2013 to Jun, 2015. The median diameter of tumors was 3.1 cm (0.7-6 cm). Follow-up were paid to all the patients who received MWA therapy. The average follow-up was 22.1±8.6 months, and the median follow-up was 18 (7-40) months.

RESULTS

All of 113 cases of patients with lung cancer experienced MWA therapy, and their tumors were found to have vacuolization, lower density and much smaller distinct shrinkage of tumor size with varying degrees. The local progression rate or relapse rate of the whole group was 15.9%. The counterpart of patients in the early-stage group was 5.7% (2/35), and the diameter of tumors in the two patients was more than 3 cm. The local progression rate or relapse rate of patients in advanced-stage group was 20.5%, wherein, 81.3% of local progression or relapse occurred to the patients with a tumorous diameter of more than 3 cm. The results indicated that the patients in advanced-stage group were vulnerable to local progression or relapse, the tumorous with greater diameter had higher incidence of local relapse. No mortality occurred within 30 days after surgery, the survival rate of patients in early-stage group at first, second, third year was respectively 97.1%, 94.1% and 84.7%. The counterpart of patients in advanced-stage group was respectively 93.6%, 87.7% and 71.7%. The difference of survival rate between both groups was not statistically significant (P=0.576). No perioperative deaths occurred, and the main complications i.e., fever, pneumothorax, pleural effusion, hemoptysis, pneumonia, and pain were slight and tolerable.

CONCLUSIONS

MWA is an effective, safe and minimally invasive treatment for the patients with lung cancer who cannot be tolerated by surgical resection.

Treatment of osteosarcoma with microwave thermal ablation to induce immunogenic cell death

Microwave ablation (MWA) has been used as a classical hyperthermic ablation method for decades with the intention to induce direct killing of tumor cells or modulation of tumor architecture. The purpose of this study was to explore whether MWA induced tumor cell death could generate an immunogenic source of tumor antigens and elicit tumor-specific immune responses, taking an alternative antitumor effects. Three kinds of osteosarcoma cell lines, respectively derived from mice, rats and human, were selected as ablation models. In vitro and in situ tumor ablation were both performed to detect the “damage-associated molecular patterns” (DAMPs) exposure level. Active ablated products vaccination resulted in complete protection in both mouse and rat tumor-bearing models, which was mediated primarily by vaccine-elicited CD8⁺ T cells. These effector cells functioned by releasing IFN-γ and TNF-α in the presence of target cells, which may trigger FasL-directed cell apoptosis. These data suggest that MWA-processed osteosarcoma cells could be applied to generate specific antitumor effects, especially for in situ ablation. Hence, MWA could be used in combination with immunotherapy, especially for patients who have failed chemotherapy or who have limited treatment options.

Cytokine-induced killer cells co-cultured with dendritic cells loaded with the protein lysate produced by radiofrequency ablation induce a specific antitumor response

Radiofrequency ablation (RFA) causes coagulative necrosis of tumor tissue and the production of local tumor protein debris. These fragments of tumor protein debris contain a large number of various antigens, which can stimulate a specific cellular immune response. In the present study, dendritic cells (DCs) were loaded with tumor protein lysate antigens that were produced in situ by RFA, and were used to treat murine colon carcinoma in combination with cytokine-induced killer (CIK) cells. Subsequent to the treatment of murine colon carcinoma by RFA, the in situ supernatant of tumor lysis was collected and the DCs were loaded with the lysate antigen to generate Ag-DCs. CIK cells induced from the spleen cells of mice were co-cultured with Ag-DCs to generate Ag-DC-CIK cells. The results revealed that the Ag-DC-CIK cells exhibited strong antitumor activity in vitro and in vivo. The morphology and immunophenotypes of these cells were determined using microscopy and flow cytometry, respectively. The cytotoxic activity of Ag-DC-CIK cells was determined using a CCK-8 assay. To establish a mouse model, mice were randomized into Ag-DC-CIK, DC-CIK, CIK and PBS control groups and monitored for tumor growth and survival time. ANOVA was used to compare the trends in the three groups for implanted tumor volumes. The log-rank test was used to compare the survival time. The present findings indicated that DCs loaded with the protein lysate antigens of tumors, produced in situ by RFA, combined with CIK cells may be a novel strategy for cancer treatment.

Chinese expert consensus workshop report: Guidelines for thermal ablation of primary and metastatic lung tumors

Although surgical resection is the primary means of curing both primary and metastatic lung cancers, about 80% of lung cancers cannot be removed by surgery. As most patients with unresectable lung cancer receive only limited benefits from traditional radiotherapy and chemotherapy, many new local treatment methods have emerged, including local ablation therapy. The Minimally Invasive and Comprehensive Treatment of Lung Cancer Branch, Professional Committee of Minimally Invasive Treatment of Cancer of the Chinese Anti-Cancer Association has organized multidisciplinary experts to develop guidelines for this treatment modality. These guidelines aim at standardizing thermal ablation procedures and criteria for selecting treatment candidates and assessing outcomes; and for preventing and managing post-ablation complications.