Image-guided radiofrequency ablation as a new treatment option for patients with lung cancer

Clinical application status and prospect of the combined anti-tumor strategy of ablation and immunotherapy

Image-guided tumor ablation eliminates tumor cells by physical or chemical stimulation, which shows less invasive and more precise in local tumor treatment. Tumor ablation provides a treatment option for medically inoperable patients. Currently, clinical ablation techniques are widely used in clinical practice, including cryoablation, radiofrequency ablation (RFA), and microwave ablation (MWA). Previous clinical studies indicated that ablation treatment activated immune responses besides killing tumor cells directly, such as short-term anti-tumor response, immunosuppression reduction, specific and non-specific immune enhancement, and the reduction or disappearance of distant tumor foci. However, tumor ablation transiently induced immune response. The combination of ablation and immunotherapy is expected to achieve better therapeutic results in clinical application. In this paper, we provided a summary of the principle, clinical application status, and immune effects of tumor ablation technologies for tumor treatment. Moreover, we discussed the clinical application of different combination of ablation techniques with immunotherapy and proposed possible solutions for the challenges encountered by combined therapy. It is hoped to provide a new idea and reference for the clinical application of combinate treatment of tumor ablation and immunotherapy.

18F-FDG PET/CT performed immediately after percutaneous ablation to evaluate outcomes of the procedure: preliminary results

Objective

To determine whether ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography performed immediately after percutaneous ablation (_iPA¹⁸F-FDG PET/CT) is useful in evaluating the outcomes of the procedure.

Materials and Methods

This was a retrospective study of 20 patients (13 males, 7 females; mean age, 65.8 ± 12.1 years) submitted to percutaneous ablation of metastases. All of the lesions treated had shown focal uptake on a ¹⁸F-FDG PET/CT scan obtained at baseline. The primary tumors were mainly colorectal cancer (in 45%) or lung cancer (in 40%). _iPA¹⁸F-FDG PET/CT was performed to identify any residual viable tumor cells. The treatment was considered a success (no viable tumor cells present) if no uptake of ¹⁸F-FDG was noted on the _iPA¹⁸F-FDG PET/CT scan.

Results

Twenty-six lesions were submitted to percutaneous ablation with either cryoablation (n = 7) or radiofrequency ablation (n = 19). The mean lesion diameter was 2.52 ± 1.49 cm. For the detection of viable tumor cells, _iPA¹⁸F-FDG PET/CT had a sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 66.7%, 95%, 88.5%, 80%, and 90.5%, respectively. There was a significant correlation between the _iPA¹⁸F-FDG PET/CT findings and the results of the follow-up studies (kappa = 0.66; p < 0.01).

Conclusion

_iPA¹⁸F-FDG PET/CT studies appear to constitute a useful means of evaluating the outcomes of percutaneous ablation. By detecting residual viable tumor cells, this strategy might allow early re-intervention, thus reducing morbidity. Studies involving larger numbers of patients are needed in order to confirm our findings.

Feasibility of Intraoperative Nerve Monitoring in Preventing Thermal Damage to the "Nerve at Risk" During Image-Guided Ablation of Tumors

PURPOSE

To assess feasibility of intraoperative neurophysiologic monitoring (IONM) during image-guided, percutaneous thermal ablation of tumors.

MATERIALS AND METHODS

From February 2009 to October 2013, a retrospective review of all image-guided percutaneous thermal ablation interventions using IONM was performed and data was compiled using electronic medical records and imaging studies.

RESULTS

Twelve patients were treated in 13 ablation interventions. In 4 patients, real-time feedback from the monitoring neurologist was used to adjust applicator placement and ablation settings. IONM was technically feasible in all procedures and there were no complications related to monitoring or ablation. All nerves at risk remained intact and of the 11 patients who could be followed, none developed new nerve deficit up to a minimum of 2 months after ablation.

CONCLUSION

IONM is safe and feasible for use during image-guided thermal ablation of tumors in the vicinity of nerves. Outcomes in this study demonstrate its potential utility in image-guided ablation interventions.

Study of survival in patients with malignant lung lesions treated with radiofrequency

OBJECTIVE

To report on the survival of a series of patients with primary and metastatic lung tumours treated with radiofrequency (RF). Four years ago we published our preliminary experience with the use of this technique.

MATERIALS AND METHODS

For a period of 8 years we have treated 59 patients (by means of a total of 70 procedures) with primary or metastatic pulmonary neoplastic lesions, which fulfilled inclusion criteria to perform the technique. They were in all cases non-surgical lesions that had been either previously treated or not. The technique was performed in the radiology suite, under conscious analgo-sedation. We treated primary pulmonary lesions, neoplastic recurrences, or metastases with curative or palliative intention (pain management).

RESULTS

Current global survival rate is 19 patients (32 %) with a mean of 26.61 ± 3.17 months (range: 20.38 ± 32.83) and a median of 16.00 ± 3.57 (range: 8.99-23.00). If we establish the difference between primary and metastatic tumours, mean survival is 27.62 ± 4.12 months in primary tumours (median: 16.00) vs. 24.65 ± 4.47 months in metastatic tumours (median: 16.00). When we studied the survival in those cases with a curative intent, mean survival in primary tumours was 30.97 ± 4.57 months (median: 21.00) vs. 25.14 ± 4.68 (median: 16.00) months in metastatic tumours.

CONCLUSIONS

RF ablation of lung lesions is a minimally invasive procedure that is useful in primary tumours (especially in stage I) and metastatic ones. RF has proven its usefulness in the multidisciplinary treatment of this pathology due to the low incidence of serious complications and survival obtained, considering that patients are elderly with significant comorbidity.

Cost and effectiveness of radiofrequency ablation versus limited surgical resection for stage I non-small-cell lung cancer in elderly patients: is less more?

PURPOSE

To retrospectively evaluate cost and mortality in 84 patients older than 65 years of age with stage IA or IB non-small-cell lung cancer treated with radiofrequency (RF) ablation or limited surgical resection (ie, wedge resection or segmentectomy) from the perspective of the payer, Medicare.

MATERIALS AND METHODS

From August 2000 to November 2009, 56 patients were treated with RF ablation and 28 with surgery who met the inclusion criteria. Patient health histories and billing charges from initial treatment to the study endpoint were collected. Charges were converted to 2009 Medicare reimbursement fees and cumulated by month. Time-event data were analyzed by using the Kaplan-Meier method. Survival functions and median survival estimates were reported with standard errors. Patient cohorts' survival functions were compared based on the Wilcoxon weighted χ(2) statistic.

RESULTS

Group demographics were comparable with the exception of age, with patients treated with RF ablation an average of 4 years older (95% confidence interval, 0.85-6.76). The overall mortality rate was lower in patients treated with surgery than in those treated with RF ablation (χ(2) = 8.0225, P = .0046), with a median cost per month lived for RF ablation recipients of $620.74, versus $1,195.92 for those treated with surgery (P = .0002, Wilcoxon rank-sum test).

CONCLUSIONS

Patients treated with surgery showed a significant increase in survival; however, those treated with RF ablation were significantly older. For patients who are not surgical candidates, RF ablation provides an alternative treatment option at a significantly lower cost.

Radiofrequency ablation of lung tumors: imaging features of the postablation zone

Radiofrequency ablation (RFA) is used to treat pulmonary malignancies. Although preliminary results are suggestive of a survival benefit, local progression rates are appreciable. Because a patient can undergo repeat treatment if recurrence is detected early, reliable post-RFA imaging follow-up is critical. The purpose of this article is to describe (a) an algorithm for post-RFA imaging surveillance; (b) the computed tomographic (CT) appearance, size, enhancement, and positron emission tomographic (PET) metabolic activity of the ablation zone; and (c) CT, PET, and dual-modality imaging with PET and CT (PET/CT) features suggestive of partial ablation or tumor recurrence and progression. CT is routinely used for post-RFA follow-up. PET and PET/CT have emerged as auxiliary follow-up techniques. CT with nodule densitometry may be used to supplement standard CT. Post-RFA follow-up was divided into three phases: early (immediately after to 1 week after RFA), intermediate (>1 week to 2 months), and late (>2 months). CT and PET imaging features suggestive of residual or recurrent disease include (a) increasing contrast material uptake in the ablation zone (>180 seconds on dynamic images), nodular enhancement measuring more than 10 mm, any central enhancement greater than 15 HU, and enhancement greater than baseline anytime after ablation; (b) growth of the RFA zone after 3 months (compared with baseline) and definitely after 6 months, peripheral nodular growth and change from ground-glass opacity to solid opacity, regional or distant lymph node enlargement, and new intrathoracic or extrathoracic disease; and (c) increased metabolic activity beyond 2 months, residual activity centrally or at the ablated tumor, and development of nodular activity.

Current status of thermal ablation treatments for lung malignancies

About 75% of lung cancer patients are not surgical candidates, either due to advanced disease or medical comorbidities. Furthermore, conventional treatments that can be offered to these patients are beneficial only to a small percentage of them. Thermal ablation is a minimally invasive treatment that is commonly used in this group of patients, and which has shown promising results. Currently, the most widely used ablation techniques in the treatment of lung malignancies are radiofrequency ablation (RFA), microwave ablation, and cryoablation. Although the most studied technique is RFA, recent studies with microwave ablation and cryoablation have shown some advantages over RFA. This article reviews the application of thermal ablation in the thorax, including patient selection, basic aspects of procedure technique, imaging follow-up, treatment outcomes, and comparison of ablation techniques.

Radiofrequency ablation of medically inoperable stage IA non-small cell lung cancer: are early posttreatment PET findings predictive of treatment outcome?

OBJECTIVE

The purpose of this study was to evaluate initial experience with (18)F-FDG PET/CT after pulmonary radiofrequency ablation of stage IA non-small cell lung cancer to determine whether treatment success or residual disease can be predicted with early postablation PET.

SUBJECTS AND METHODS

Thirty patients with medically inoperable stage IA non-small cell lung cancer (12 men, 18 women; median age, 76 years; range, 60-87 years) underwent outpatient CT-guided radiofrequency ablation over a 33-month period. Mean tumor size was 2.0 cm (range, 1.3-2.9 cm). PET/CT was performed within 60 days before radiofrequency ablation (RFA), within 4 days after RFA, and 6 months after RFA. Metabolic response was categorized as complete response or partial or no response at early post-RFA PET/CT and complete response, partial response, or progressive metabolic disease at 6-month post-RFA PET/CT and was compared with the 1-year clinical event rate (death, disease progression at contrast-enhanced CT, or repeat ablation).

RESULTS

Early PET/CT images, obtained within 4 days of RFA, were evaluable for 26 patients (23 at 6 months). Patients with a complete metabolic response at early PET/CT had a 1-year event rate of 43%, whereas those with partial or no response or disease progression had a 1-year event rate of 67% (p = 0.27). Patients with a complete metabolic response at 6-month PET/CT had a 1-year event rate of 0%. Those with a partial response and those with disease progression had an overall event rate of 75% (p = 0.001).

CONCLUSION

Early post-RFA PET/CT is not necessary and 6-month post-RFA PET/CT findings correlate better with clinical outcome at 1 year.

Evaluation of treatment response after nonoperative therapy for early-stage non-small cell lung carcinoma

Nonsurgical management of early primary lung cancer has grown tremendously in recent years, and today, available options extend far beyond that of conventional radiation therapy (CRT) to include minimally invasive image-guided delivery of thermal energies, specifically radiofrequency ablation, microwave ablation, and cryoablation, and more conformal stereotactic body radiation therapy. Because the tumor is never resected with these nonoperative interventions, histopathological evaluation of tumor margins for the presence of residual tumor is impossible, and as such, tumor response after each of these therapies is largely based on imaging. To date, computerized tomography and computerized tomography-positron emission tomography remain the most readily available modalities for assessment of therapeutic efficacy, and to this end as detailed within this article, strict imaging survey and familiarity with the expected imaging characteristics of the treated tumor will aid in recognition of unexpected findings, specifically those of incomplete therapy and/or tumor recurrence.

Thermal ablation of lung tumors

Thermal ablation can be applied to treat any thoracic malignancy: primary lung cancers, recurrent primary lung cancers, metastatic disease, chest wall masses, and painful, bony metastases. Since the first reported use of thermal ablation for lung cancer in 2000 there has been an explosive use of the procedure, and by 2010 the number of procedures to treat thoracic malignancy is expected to exceed 150,000 per year. Presently, thermal ablation is best used for patients with early-stage lung cancers in patients who are not surgical candidates, patients with small and favorably located pulmonary metastases, and patients in whom palliation of tumor-related symptoms is the goal. Radiofrequency ablation, microwave ablation, and cryoablation are novel treatment modalities for lung cancer and can safely accomplish tumor destruction and even complete eradication of tumor in patients who are not candidates for surgical resection. In this article, we discuss technical considerations for each modality and the periprocedure and postprocedure management of patients with this disease.

[Historic landmarks in the study of lung cancer]

This study reviews the milestones which have been reached in the study of lung cancer, from its first early descriptions up until the end of the twentieth century. The study accompanies the birth of this new clinical entity, underlining the difficulties inherent in its diagnosis, its ever-growing increase and traces the growth of its aetiological factors, placing particular emphasis on smoking. In tandem with this, the study delves into the clinical aspects, along with new discoveries in imaging techniques and endoscopic and bioscopic techniques. It also looks at the histopathological classifications of bronchopulmonary tumours and the various staging systems which have been used over the course of time as well as the importance of mapping the disease and the different treatment weapons which have successively become available in the fight against it. The study also takes a look at the scales used in evaluating patients' physiological condition, the criteria used in evaluating response to oncostatic treatment and the role some international and national scientific societies and medical associations have played in adding to the increasing medical knowledge of lung cancer. The study clearly shows to whom we are indebted for each advance. This is a fascinating sweep of history - as is the story of all medical progress - and one we feel is important to understand, in order for us to see more clearly where we are now.

Theoretical modeling for radiofrequency ablation: state-of-the-art and challenges for the future

Radiofrequency ablation is an interventional technique that in recent years has come to be employed in very different medical fields, such as the elimination of cardiac arrhythmias or the destruction of tumors in different locations. In order to investigate and develop new techniques, and also to improve those currently employed, theoretical models and computer simulations are a powerful tool since they provide vital information on the electrical and thermal behavior of ablation rapidly and at low cost. In the future they could even help to plan individual treatment for each patient. This review analyzes the state-of-the-art in theoretical modeling as applied to the study of radiofrequency ablation techniques. Firstly, it describes the most important issues involved in this methodology, including the experimental validation. Secondly, it points out the present limitations, especially those related to the lack of an accurate characterization of the biological tissues. After analyzing the current and future benefits of this technique it finally suggests future lines and trends in the research of this area.

Radiofrequency Ablation Followed by Conventional Radiotherapy for Medically Inoperable Stage I Non-small Cell Lung Cancer

PURPOSES

The standard treatment of stage I non-small cell lung cancer (NSCLC) is surgical resection. Some patients are poor surgical candidates due to severe comorbid medical conditions. Radiotherapy alone has historically been used in this patient population with limited success. Radiofrequency ablation (RFA) is an image-guided, thermally mediated ablative technique recently applied to lung tumors. Combination therapy with both these treatments has not been previously performed. We report our experience with combined CT-guided RFA and conventional radiotherapy in 24 medically inoperable patients with a minimum of 2-year study follow-up in surviving patients.

PATIENTS AND METHODS

Twenty-four consecutive, medically inoperable patients with biopsy-proven, stage I NSCLC were treated with CT-guided RFA followed by radiotherapy to a dose of 66 Gy. RFA was performed with a single or cluster cool-tip F electrode; 21 patients were staged before therapy using fluorodeoxyglucose-positron emission tomography.

RESULTS

There were 14 women and 10 men (median age, 76 years; range, 58 to 85 years). The histologic subtypes were squamous cell (n = 13), adenocarcinoma (n = 5), and undifferentiated (n = 6). All patients received RFA followed by three-dimensional conformal radiotherapy. There were no treatment-related deaths or grade 3/4 toxicities. Pneumothorax requiring chest tubes developed in three patients (12.5%). At a mean follow-up period of 26.7 months (range, 6 to 65 months), 14 patients (58.3%) died, with cumulative survival rates of 50% and 39% at the end of 2 years and 5 years, respectively. Ten of the deaths were cancer related. Two patients had local recurrence (8.3%), while nine patients had systemic metastatic disease. Three patients died of respiratory failure with no evidence of active disease, and one patient died of a cerebrovascular accident at 18-month follow-up. Pleural effusions developed after treatment in six patients (25%), which proved to be malignant in one patient.

CONCLUSION

RFA followed by conventional radiotherapy is feasible in this population of medically inoperable stage I NSCLC patients. Procedural complication rates are low, and no additional major toxicities were seen despite the addition of RFA. Local control and survival rates appear to be better than with radiotherapy alone.