Percutaneous radiofrequency ablation of lung tumors with expandable needle electrodes: current status

Apoptosis of Lewis Lung Carcinoma Cells Induced by Microwave via p53 and Proapoptotic Proteins In vivo

Background:

Microwave therapy is a minimal invasive procedure and has been employed in clinical practice for the treatment of various types of cancers. However, its therapeutic application in non-small-cell lung cancer and the underlying mechanism remains to be investigated. This study aimed to investigate its effect on Lewis lung carcinoma (LLC) tumor in vivo.

Methods:

Fifty LLC tumor-bearing C57BL/6 mice were adopted to assess the effect of microwave radiation on the growth and apoptosis of LLC tumor in vivo. These mice were randomly assigned to 10 groups with 5 mice in each group. Five groups were treated by single pulse microwave at different doses for different time, and the other five groups were radiated by multiple-pulse treatment of a single dose. Apoptosis of cancer cells was determined by terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. Western blotting was applied to detect the expression of proteins.

Results:

Single pulse of microwave radiation for 5 min had little effect on the mice. Only 15-min microwave radiation at 30 mW/cm² significantly increased the mice body temperature (2.20 ± 0.82)°C as compared with the other groups (0.78 ± 0.29 °C, 1.24 ± 0.52 °C, 0.78 ± 0.42 °C, respectively), but it did not affect the apoptosis of LLC tumor cells significantly. Continous microwave radiation exposure, single dose microwave radiation once per day for up to seven days, inhibited cell division and induced apoptosis of LLC tumor cells in a dose- and duration-dependent manner. It upregulated the protein levels of p53, Caspase 3, Bax and downregulated Bcl-2 protein.

Conclusions:

Multiple exposures of LLC-bearing mice to microwave radiation effectively induced tumor cell apoptosis at least partly by upregulating proapoptotic proteins and downregulating antiapoptotic proteins. Continuous radiation at low microwave intensity for a short time per day is promising in treating non-small-cell lung cancer.

Local recurrence of small cell lung cancer following radiofrequency ablation is induced by HIF-1α expression in the transition zone

Local recurrence of lung cancer following radiofrequency ablation (RFA) treatment is common. The aims of the present study were to assess how RFA treatment affects the growth of small cell lung cancer (SCLC) micrometastases in the transition zone (TZ) surrounding the ablated region and in the reference zones (RZs) of the ablated or unablated lobes and to identify the molecular mechanism(s) of lung cancer recurrence following RFA treatment. After lung micrometastases of human SCLCs had formed, RFA treatment was applied to the right upper lobe (RUL) of the lung in nude mice. Hypoxia inducible factor (HIF)-1α expression, proliferation and angiogenesis potential both in the TZ and RZ were evaluated over time. Separately, at day 1, 7 and 14 following RFA treatment, the growth of micrometastases showed an ~2-fold increase in the TZ compared to the RZ of the unablated lobe, as the right lower lobe (RLL) and the growth of micrometastases in the RZ of the RUL was also induced by RFA. In addition, accelerated tumor growth in the TZ was induced by HIF-1α, but was not associated with tissue angiogenesis potential. We concluded that local recurrences of SCLCs caused by overproliferation of micrometastases following RFA treatment were driven by HIF-1α, although angiogenesis was not the driving force in the TZ.

An ex vivo human lung model for ultrasound-guided high-intensity focused ultrasound therapy using lung flooding

The usability of an ex vivo human lung model for ablation of lung cancer tissue with high-intensity focused ultrasound (HIFU) is described. Lung lobes were flooded with saline, with no gas remaining after complete atelectasis. The tumor was delineated sono-morphologically. Speed of sound, tissue density and ultrasound attenuation were measured for flooded lung and different pulmonary cancer tissues. The acoustic impedance of lung cancer tissue (1.6-1.9 mega-Rayleighs) was higher than that of water, as was its attenuation coefficient (0.31-0.44 dB/cm/MHz) compared with that of the flooded lung (0.12 dB/cm/MHz). After application of HIFU, the temperature in centrally located lung cancer surrounded by the flooded lung increased as high as 80°C, which is sufficient for treatment. On the basis of these preliminary results, ultrasound-guided HIFU ablation of lung cancer, by lung flooding with saline, appears feasible and should be explored in future clinical studies.

Ask the Experts: How important is radiofrequency ablation in lung cancer?

Terrance T Healey is the director of Thoracic Radiology at Rhode Island Hospital (RI, USA) and an Assistant Professor of Diagnostic Imaging at the Alpert Medical School of Brown University (RI, USA). Healey received his medical degree from the combined Dartmouth Medical School–Brown Medical School Program in 2003, completed his residency in radiology at Brown University in 2008 and a thoracic radiology fellowship at the Massachusetts General Hospital (MA, USA) in 2009. He joined the faculty staff at Rhode Island Hospital and Brown University in 2009.

Robert C Ward is one of the chief residents within the Department of Diagnostic Imaging at Rhode Island Hospital (RI, USA) and the Alpert Medical School of Brown University (RI, USA). Ward received his medical degree from the George Washington University (Washington, DC, USA) in 2010.

Damian E Dupuy is the director of Tumor Ablation at Rhode Island Hospital (RI, USA) and a Professor of Diagnostic Imaging at The Warren Alpert Medical School of Brown University (RI, USA). Dupuy received his medical degree from the University of Massachusetts Medical School (MA, USA) in 1988 and completed his residency in radiology at The New England Deaconess Hospital (MA, USA) and Harvard Medical School (MA, USA) in 1993. After residency, Dupuy joined the staff at Massachusetts General Hospital (MA, USA) where he worked in the Abdominal Imaging and Bone and Joint Divisions. In 1997, Dupuy joined the Department of Diagnostic Imaging at Rhode Island Hospital and Brown University. Dupuy, a pioneer in the use of image-guided ablation, helped broaden clinical applications to successfully combat cancer involving the kidney, liver, lung, head and neck, adrenal gland and skeleton. Other newer technologies, such as percutaneous microwave ablation, cryoablation and combination therapies using radiofrequency ablation with external radiation or brachytherapy, have been pioneered by Dupuy who has been the principal investigator of two National Cancer Institute-funded multicenter trials. Dupuy has received national awards for research and teaching from the American College of Radiology Imaging Network and the Radiological Society of North America where he is currently the Chair of the Interventional Oncology Symposium featured at the Annual Meeting of the Radiological Society of North America and a Fellow of the American College of Radiology. Dupuy is a member of the Radiological Society of North America, The New England Roentgen Ray Society, The American College of Radiology, Rhode Island Radiological Society and the Society of Interventional Radiology. Dupuy has published over 150 publications and given over 120 invited lectures in the field of radiology and image-guided ablation, both nationally and internationally.

Current oncologic applications of radiofrequency ablation therapies

Radiofrequency ablation (RFA) uses high frequency alternating current to heat a volume of tissue around a needle electrode to induce focal coagulative necrosis with minimal injury to surrounding tissues. RFA can be performed via an open, laparoscopic, or image guided percutaneous approach and be performed under general or local anesthesia. Advances in delivery mechanisms, electrode designs, and higher power generators have increased the maximum volume that can be ablated, while maximizing oncological outcomes. In general, RFA is used to control local tumor growth, prevent recurrence, palliate symptoms, and improve survival in a subset of patients that are not candidates for surgical resection. It’s equivalence to surgical resection has yet to be proven in large randomized control trials. Currently, the use of RFA has been well described as a primary or adjuvant treatment modality of limited but unresectable hepatocellular carcinoma, liver metastasis, especially colorectal cancer metastases, primary lung tumors, renal cell carcinoma, boney metastasis and osteoid osteomas. The role of RFA in the primary treatment of early stage breast cancer is still evolving. This review will discuss the general features of RFA and outline its role in commonly encountered solid tumors.

Effects of radiofrequency ablation on normal lung tissue in a swine model

RATIONALE AND OBJECTIVES

To determine the effect of radiofrequency (RF) ablation on normal lung tissue in an animal model.

MATERIALS AND METHODS

RF ablation of lung tissue was performed on eight swine under computed tomographic control. Group A (n = 4) received peripheral ablation (subpleural needle placement) and group B (n = 4) received central ablation (hilar needle placement). RF ablation was applied via a single 4.5-gauge internally cooled electrode with a 2-cm tip for 12 minutes. The ablation was monitored with computed tomography at 3, 7, and 12 minutes, and 10 minutes after ablation. After 3, 7, 40, and 60 days, computed tomography was performed, and the animals were sacrificed to examine the lung tissue both macroscopically and histopathologically.

RESULTS

There were no deaths from RF ablation. In group A, coagulative necrosis was resorbed almost completely and transformed into a fibrotic scar after 60 days. No pneumothorax, pleural effusion, or lung abscess was observed. In group B, there was also a transformation of the necrosis into connective tissue. Neither the pulmonary vessels nor the bronchi of the hilum abutting the coagulative necrosis were damaged. After 60 days, no vascular thrombosis, bleeding, aneurysm, bronchial stenosis, or bronchopulmonary fistula was observed.

CONCLUSION

RF ablation of lung tissue affects coagulation necrosis, causing scar transformation. There was no damage to either great vessels or bronchi. The application of RF ablation for tumors located in or near functional structures appears feasible without severe complications.

Increased ablation zones using a cryo-based internally cooled bipolar RF applicator in ex vivo bovine liver

PURPOSE

To evaluate the feasibility of ex vivo ablation implementing a cryo-based internally cooled bipolar radiofrequency (RF) applicator and to determine the influence of power and gas pressure on the size and shape of the resulting ablation zones.

MATERIALS AND METHODS

Two hundred twenty-five ablations were performed using a custom-built internally CO2-cooled bipolar cryo RF applicator in ex vivo bovine livers. The active tip of the applicator was 55 mm long. RF power (32-50 watts) and gas pressure of cooling medium (500-600 psi) were varied independently. Power was applied in continuous mode. Control group experiments were carried out solely using the RF function at 32, 40, and 50 watts. Ablation duration was 15 minutes for all applications. Experiments were repeated 5 times for all parameter combinations. Short and long axes of the induced white ablation zone were macroscopically assessed. The ablation zone was referred to as homogeneous if complete ablation was observed without spots of untreated tissue. The short axis diameters for the simultaneous application of cryo and RF function were analyzed using a multiple linear regression analysis. An unpaired Mann-Whitney U test was used to analyze the differences between the short axes with RF alone and RF using cryo cooling.

RESULTS

All ablation zones were homogeneous. Using simultaneous RF ablation function and gas cooling with a single applicator, the long axes of the ablation zones ranged between 42 +/- 2 mm (mean +/- SD) and 59 +/- 5 mm, the short axes between 24 +/- 1 and 44 +/- 1 mm, depending on the parameter combination. At a stable gas pressure level, short axes increased with rising power levels and decreased after reaching a maximum. The maxima of the short axis increased with higher gas pressure levels and were shifted to higher power values. Optimal parameter settings were 46 to 50 watts and 600 psi gas pressure, resulting in a short axis of 44 +/- 1 mm. Short axis weakly correlated with gas pressure (r2 = 0.10) and power (r2 = 0.34) alone, whereas the correlation was r2 = 0.76 for the combined factors. Without cooling, short axis diameters were significantly shorter (P < 0.05), ranging between 13 +/- 2 mm at 50 watts and 15 +/- 2 mm at 32 watts.

CONCLUSION

The results of this initial ex vivo study show that the combined cryo RF ablation device allows for large ablation volumes using a single needle, which is superior to RF ablation alone.

Radiofrequency ablation of non-small-cell carcinoma of the lung under real-time FDG PET CT guidance

Radiofrequency ablation (RFA) is a well-established method in treatment of patients with lung carcinomas who are not candidates for surgical resection. Usually computed tomographic (CT) guidance is used for the procedure, thus enabling needle placement and permitting evaluation of complications such as pneumothorax and bleeding. (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is generally used for tumor activity assessment and is therefore useful in follow-up after tumor treatment. A method that provides real-time image-based monitoring of RFA to ensure complete tumor ablation would be a valuable tool. In this report, we describe the behavior of preinjected FDG during PET CT-guided RFA of a non-small-cell lung carcinoma and discuss the value of FDG as a tool to provide intraprocedure monitor ablation. The size and the form of the activity changed during ablation. Ablation led to increase of the size and blurring and irregularity of the contour compared to pretreatment imaging. The maximal standardized uptake value decreased only slightly during the procedure. Therefore, before RFA, FDG PET can guide initial needle placement, but it does not serve as a monitoring tool to evaluate residual viable tissue during the procedure.

[Effectiveness of radiofrequency ablation of lung tumours ]

BACKGROUND

There has been great success in the treatment of primary and secondary tumours of the liver using radiofrequency ablation (RFA) therapy, resulting in this method being used for other solid tumours such as in the lung. However, concerning lung cancer only few data are available about the histomorphological effects of this method. The aim of this study was to analyse the effects of RFA therapy in tumours of the lung.

PATIENTS AND METHODS

Eleven patients with non-small-cell lung cancer and one with a lung metastasis (primary tumour identified as urothelial carcinoma) underwent RFA therapy followed by resection of the affected lobe. One patient with a metastasis of the liver was included for comparison of treatment effects. Histomorphological analysis of the collected material was used to measure the amount of necrosis.

RESULTS

None of the treated tumours of the lung showed complete necrosis after applying RFA therapy. In contrast, this method with the control metastasis of the liver resulted in complete thermal destruction.

CONCLUSION

Our results indicate that RFA therapy is not adequate for successful induction of necrosis in tumours of the lung. Therefore the use of this method has to be considered extremely carefully as a palliative treatment option in tumours of the lung.

Radiofrequency ablation of lung metastases: factors influencing success

This paper analyses the factors associated with successful radiofrequency ablation (RFA) of lung metastases. The study group comprised 37 patients [19 female, mean age 61 (34-83)] with 72 metastases who had follow-up CT scans available for analysis and for those with no recurrence >6 months follow-up. Internally cooled electrodes were used in 64 and expandable electrodes in 8. The tumour size and location, electrode type, number of ablations, duration of ablation, year of treatment and tumour contact with vessels larger than 3 mm were recorded. The mean tumour diameter was 1.8 cm (0.4-6.6 cm). Mean follow-up in those without recurrence was 13.1 months (6-48). Recurrence was common in larger tumours, occurring in 7/7 (100%) tumours >3.5 cm compared with 18/65 (28%) < or = 3.5 cm (P < 0.01). Recurrence occurred in 14/24 (58%) tumours in direct contact with large vessels compared with 11/48 (23%) of the remainder (P = 0.04). On multivariate analysis, size was the dominant feature (P = 0.013); vessel contact and peripheral location did not reach significance (P = 0.056 and 0.054 respectively). Peripheral tumours less than 3.5 cm with no large vessel contact are the optimal tumours for RFA.

[Interventional oncology for lung tumors]

Lung tumors and pulmonary metastases together are the most common cause of cancer-related death in men and the second most frequent in women. Up to now, surgical resection has remained the gold standard in the treatment of pulmonary tumors, being the only treatment option that was potentially curative and offered the possibility of a significant increase in life expectancy after successful therapy. Over the past decade, percutaneous radiofrequency ablation (RFA) has gained worldwide acceptance in the treatment of primary and secondary tumors of the liver with curative intent, so that indications for RFA have been extended to embrace tumors in other organs, e.g. the lung. Since the first case results were described, the number of publications dealing with the treatment of lung tumors using thermal ablative therapies has increased significantly. The aims of the present article are to give a short overview of emerging therapies such as cyberknife surgery and also, especially, to describe the indications for and technique of RFA, to discuss the ideal method of follow-up, and to highlight possible complications of the therapy and the current results of RFA of primary and secondary lung tumors. In addition, the value of combining RFA with other therapy modes (especially chemotherapy and radiation therapy)is briefly treated.

A Newly Developed Perfused Umbrella Electrode for Radiofrequency Ablation: An Ex Vivo Evaluation Study in Bovine Liver

The purpose of this study was to evaluate the effectiveness of a newly developed perfused monopolar radiofrequency (RF) probe with an umbrella-shaped array. A perfused umbrella-shaped monopolar RF probe based on a LeVeen electrode (Boston Scientific Corp., Natick, MA, USA) with a 3-cm array diameter was developed. Five different configurations of this electrode were tested: (a) perfusion channel/endhole, (b) perfusion channel/endhole + sideholes, (c) 1 cm insulation removed at the tip, (d) 1 cm insulation removed at the tip + perfusion channel/endhole, and (e) 1 cm insulation removed at the tip + perfusion channel/endhole + sideholes. An unmodified LeVeen electrode served as a reference standard. RF ablations were performed in freshly excised bovine liver using a commercial monopolar RF system with a 200-W generator (RF 3000; Boston Scientific Corp.). Each electrode was tested 10 times applying the vendor's recommended ablation protocol combined with the preinjection of 2 ml 0.9% saline. Volumes and shapes of the lesions were compared. Lesions generated with the original LeVeen electrode showed a mean volume of 12.74 +/- 0.52 cm(3). Removing parts of the insulation led to larger coagulation volumes (22.65 +/- 2.12 cm(3)). Depending on the configuration, saline preinjection resulted in a further increase in coagulation volume (25.22 +/- 3.37 to 31.28 +/- 2.32 cm(3)). Besides lesion volume, the shape of the ablation zone was influenced by the configuration of the electrode used. We conclude that saline preinjection in combination with increasing the active tip length of the umbrella-shaped LeVeen RF probe allows the reliable ablation of larger volumes in comparison to the originally configured electrode.

Radiofrequency ablation of lung tumours

Radiofrequency ablation (RFA) is a well-established local therapy for hepatic malignancies. It is rapidly emerging as an effective treatment modality for small lesions elsewhere in the body, in particular, the kidney and the lung. It is a relatively safe and minimally invasive treatment for small lung malignancies, both primary and secondary. In particular, it is the preferred form of treatment for non-surgical candidates.

This paper describes the technique employed for radiofrequency ablation of lung tumours, as well as the protocol established, at the Mount Elizabeth Hospital, Singapore.