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.

Usefulness of percutaneous microwave ablation for large non-small cell lung cancer: A preliminary report

The role of microwave ablation (MWA) in patients with non-small cell lung cancer (NSCLC) remains ill-defined. This retrospective study evaluated the oncological outcomes of CT-guided MWA in patients with large NSCLC. Kaplan-Meier analysis was used to evaluate overall survival (OS) and cancer-specific survival (CSS). The log-rank test was used to compare survival between patients with an NSCLC size greater or smaller than 4 cm. The likelihood of local tumor progression (LTP) was analyzed using a multivariable regression model. A total of 53 patients with 65 tumors were analyzed. The mean tumor size was 5.0±1.8 cm. At the 1-month CT scan, complete tumor ablation was observed in 44.6% of cases. In 18.5% of cases a redo-MWA session was carried out, while in 4.6%, a third MWA was necessary to obtain complete tumor necrosis. The mean follow-up was 28.1±20.6 months with a median duration of 21.5 months. The 1-year, 2-year, 3-year and 5-year OS rates were 78.2, 48.3, 34.8 and 18.3%, respectively. The median CSS was 25 months (95% CI 15.5–34.5). The 1-year, 2-year, 3-year and 5-year CSS rates were 84.3, 53.7, 42.1 and 30.0%, respectively. OS in patients with tumor size ≥4 cm was significantly lower when compared with those having smaller tumors (P=0.03). LTP was observed in 19 patients (35.8%). Incomplete tumor ablation [odds ratio (OR) 6.57; P<0.05] and tumor size ≥4 cm (OR 0.18; P<0.05) were significant independent predictors of LTP. In conclusion, CT-guided MWA may represent a useful tool in the multimodality treatment of patients with large advanced NSCLC.

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.

Evaluation of lung tumor response to therapy: Current and emerging techniques

Lung tumor response to therapy may be evaluated in most instances by morphological criteria such as RECIST 1.1 on computed tomography (CT) or magnetic resonance imaging (MRI). However, those criteria are limited because they are based on tumoral dimensional changes and do not take into account other morphologic criteria such as density evaluation, functional or metabolic changes that may occur following conventional or targeted chemotherapy. New techniques such as dual-energy CT, PET-CT, MRI including diffusion-weighted MRI has to be considered into the new technical armamentarium for tumor response evaluation. Integration of all informations provided by the different imaging modalities has to be integrated and represents probably the future goal of tumor response evaluation. The aim of the present paper is to review the current and emerging imaging criteria used to evaluate the response of therapy in the field of lung cancer.

Thermal Ablation of Colorectal Lung Metastases: Retrospective Comparison Among Laser-Induced Thermotherapy, Radiofrequency Ablation, and Microwave Ablation

OBJECTIVE

The purpose of this study is to retrospectively evaluate local tumor control, time to tumor progression, and survival rates among patients with lung metastatic colorectal cancer who have undergone ablation therapy performed using laser-induced thermotherapy (LITT), radiofrequency ablation (RFA), or microwave ablation (MWA).

MATERIALS AND METHODS

Data for this retrospective study were collected from 231 CT-guided ablation sessions performed for 109 patients (71 men and 38 women; mean [± SD] age, 68.6 ± 11.2 years; range, 34-94 years) from May 2000 to May 2014. Twenty-one patients underwent LITT (31 ablations), 41 patients underwent RFA (75 ablations), and 47 patients underwent MWA (125 ablations). CT scans were acquired 24 hours after each therapy session and at follow-up visits occurring at 3, 6, 12, 18, and 24 months after ablation. Survival rates were calculated from the time of the first ablation session, with the use of Kaplan-Meier and log-rank tests. Changes in the volume of the ablated lesions were measured using the Kruskal-Wallis method.

RESULTS

Local tumor control was achieved in 17 of 25 lesions (68.0%) treated with LITT, 45 of 65 lesions (69.2%) treated with RFA, and 91 of 103 lesions (88.3%) treated with MWA. Statistically significant differences were noted when MWA was compared with LITT at 18 months after ablation (p = 0.01) and when MWA was compared with RFA at 6 months (p = 0.004) and 18 months (p = 0.01) after ablation. The overall median time to local tumor progression was 7.6 months. The median time to local tumor progression was 10.4 months for lesions treated with LITT, 7.2 months for lesions treated with RFA, and 7.5 months for lesions treated with MWA, with no statistically significant difference noted. New pulmonary metastases developed in 47.6% of patients treated with LITT, in 51.2% of patients treated with RFA, and in 53.2% of patients treated with MWA. According to the Kaplan-Meier test, median survival was 22.1 months for patients who underwent LITT, 24.2 months for those receiving RFA, and 32.8 months for those who underwent MWA. The overall survival rate at 1, 2, and 4 years was 95.2%, 47.6%, and 23.8%, respectively, for patients treated with LITT; 76.9%, 50.8%, and 8.0%, respectively, for patients treated with RFA; and 82.7%, 67.5%, and 16.6%, respectively, for patients treated with MWA. The log-rank test revealed no statistically significant difference among LITT, RFA, and MWA. The progression-free survival rate at 1, 2, 3, and 4 years was 96.8%, 52.7%, 24.0%, and 19.1%, respectively, for patients who underwent LITT; 77.3%, 50.2%, 30.8%, and 16.4%, respectively, for patients who underwent RFA; and 54.6%, 29.1%, 10.0%, and 1.0%, respectively, for patients who underwent MWA, with no statistically significant difference noted among the three ablation methods.

CONCLUSION

LITT, RFA, and MWA can be used as therapeutic options for lung metastases resulting from colorectal cancer. Statistically significant differences in local tumor control revealed a potential advantage in using MWA. No differences in time to tumor progression or survival rates were detected when the three different ablation methods were compared.

Assessing Tumor Response to Treatment in Patients with Lung Cancer Using Dynamic Contrast-Enhanced CT

The aim of this study was to provide an overview of the literature available on dynamic contrast-enhanced computed tomography (DCE-CT) as a tool to evaluate treatment response in patients with lung cancer. This systematic review was compiled according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only original research articles concerning treatment response in patients with lung cancer assessed with DCE-CT were included. To assess the validity of each study we implemented Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). The initial search yielded 651 publications, and 16 articles were included in this study. The articles were divided into groups of treatment. In studies where patients were treated with systemic chemotherapy with or without anti-angiogenic drugs, four out of the seven studies found a significant decrease in permeability after treatment. Four out of five studies that measured blood flow post anti-angiogenic treatments found that blood flow was significantly decreased. DCE-CT may be a useful tool in assessing treatment response in patients with lung cancer. It seems that particularly permeability and blood flow are important perfusion values for predicting treatment outcome. However, the heterogeneity in scan protocols, scan parameters, and time between scans makes it difficult to compare the included studies.

Hybrid Type iterative reconstruction method vs. filter back projection method: Capability for radiation dose reduction and perfusion assessment on dynamic first-pass contrast-enhanced perfusion chest area-detector CT

PURPOSE

To directly compare the capability of hybrid-type iterative reconstruction (i.e., adaptive iterative dose reduction using 3D processing: AIDR 3D) and filter back projection (FBP) for radiation dose reduction during dynamic contrast-enhanced (CE-) perfusion area-detector CT (ADCT) for lung and nodule perfusion assessment.

MATERIALS AND METHODS

Thirty-six patients with lung cancers who underwent perfusion ADCT (SD-ADCT) at 120 mA and were enrolled in this study. ADCT data at 80 mA (reduced-dose ADCT: RD-ADCT), 60 mA (low-dose ADCT: LD-ADCT) and 40 mA (very low-dose ADCT: VLD-ADCT) were computationally simulated using SD-ADCT data, and reconstructed with and without AIDR 3D. Image noise and lung and nodule perfusion parameters were evaluated using ROI measurements. To determine the utility of AIDR 3D for dose reduction, image noise was compared between each protocol with and without AIDR 3D by means of the t-test. Correlations and limits of agreement for parameters obtained with SD-ADCT and other protocols were also evaluated.

RESULTS

Image noise of all protocols with AIDR 3D was significantly lower than that of LD-ADCT and VLD-ADCT without AIDR 3D (p<0.05). Significant correlations for image noise between SD-ADCT and all protocols with AIDR 3D (0.45 ≤ r ≤ 0.99, p<0.0001) were equal to or better than that without AIDR 3D (0.28 ≤ r ≤ 0.99, p<0.0001). The limits of agreement for perfusion parameters with AIDR 3D were smaller than those without AIDR 3D for each tube current.

CONCLUSION

AIDR 3D is more effective than FBP for dose reduction of perfusion ADCT while maintaining image quality and reducing measurement errors.

Imaging of Tumor Angiogenesis for Radiologists--Part 2: Clinical Utility

Angiogenesis is a key cancer hallmark involved in tumor growth and metastasis development. Angiogenesis and tumor microenvironment significantly influence the response of tumors to therapies. Imaging techniques have changed our understanding of the process of angiogenesis, the resulting vascular performance, and the tumor microenvironment. This article reviews the status and potential clinical value of the imaging modalities used to assess the status of tumor vasculature in vivo, before, during, and after treatment.

Functional imaging biomarkers for assessing response to treatment in liver and lung metastases

Management of patients with metastatic cancer and development of new treatments rely on imaging to provide non-invasive biomarkers of tumour response and progression. The widely used size-based criteria have increasingly become inadequate where early measures of response are required to avoid toxicity of ineffective treatments, as biological, physiologic, and molecular modifications in tumours occur before changes in gross tumour size. A multiparametric approach with the current range of imaging techniques allows functional aspects of tumours to be simultaneously interrogated. Appropriate use of these imaging techniques and their timing in relation to the treatment schedule, particularly in the context of clinical trials, is fundamental. There is a lack of consensus regarding which imaging parameters are most informative for a particular disease site and the best time to image so that, despite an increasing body of literature, open questions on these aspects remain. In addition, standardization of these new parameters is required. This review summarizes the published literature over the last decade on functional and molecular imaging techniques in assessing treatment response in liver and lung metastases.

Functional imaging in lung cancer

Lung cancer represents an increasingly frequent cancer diagnosis worldwide. An increasing awareness on smoking cessation as an important mean to reduce lung cancer incidence and mortality, an increasing number of therapy options and a steady focus on early diagnosis and adequate staging have resulted in a modestly improved survival. For early diagnosis and precise staging, imaging, especially positron emission tomography combined with CT (PET/CT), plays an important role. Other functional imaging modalities such as dynamic contrast-enhanced CT (DCE-CT) and diffusion-weighted MR imaging (DW-MRI) have demonstrated promising results within this field. The purpose of this review is to provide the reader with a brief and balanced introduction to these three functional imaging modalities and their current or potential application in the care of patients with lung cancer.

Metastases to the liver from neuroendocrine tumors: effect of duration of scan acquisition on CT perfusion values

PURPOSE

To assess the effects of acquisition duration on computed tomographic (CT) perfusion parameter values in neuroendocrine liver metastases and normal liver tissue.

MATERIALS AND METHODS

This retrospective study was institutional review board approved, with waiver of informed consent. CT perfusion studies in 16 patients (median age, 57.5 years; range, 42.0-69.7 years), including six men (median, 54.1 years; range, 42.0-69.7), and 10 women (median, 59.3 years; range 43.6-66.3), with neuroendocrine liver metastases were analyzed by means of distributed parametric modeling to determine tissue blood flow, blood volume, mean transit time, permeability, and hepatic arterial fraction for tumors and normal liver tissue. Analyses were undertaken with acquisition time of 12-590 seconds. Nonparameteric regression analyses were used to evaluate the functional relationships between CT perfusion parameters and acquisition duration. Evidence for time invariance was evaluated for each parameter at multiple time points by inferring the fitted derivative to assess its proximity to zero as a function of acquisition time by using equivalence tests with three levels of confidence (20%, 70%, and 90%).

RESULTS

CT perfusion parameter values varied, approaching stable values with increasing acquisition duration. Acquisition duration greater than 160 seconds was required to obtain at least low confidence stability in any of the CT perfusion parameters. At 160 seconds of acquisition, all five CT perfusion parameters stabilized with low confidence in tumor and normal tissues, with the exception of hepatic arterial fraction in tumors. After 220 seconds of acquisition, there was stabilization with moderate confidence for blood flow, blood volume, and hepatic arterial fraction in tumors and normal tissue, and for mean transit time in tumors; however, permeability values did not satisfy the moderate stabilization criteria in both tumors and normal tissue until 360 seconds of acquisition. Blood flow, mean transit time, permeability, and hepatic arterial fraction were significantly different between tumor and normal tissue at 360 seconds (P < .001).

CONCLUSION

CT perfusion parameter values are affected by acquisition duration and approach progressively stable values with increasing acquisition times. Online supplemental material is available for this article.

Effect of duration of scan acquisition on CT perfusion parameter values in primary and metastatic tumors in the lung

OBJECTIVES

To assess the effect of acquisition duration (T(acq)) and pre-enhancement set points (T₁) on computer tomography perfusion (CT(p)) parameter values in primary and metastatic tumors in the lung.

MATERIALS AND METHODS

24 lung CT(p) datasets (10 primary; 14 metastatic), acquired using a two phase protocol spanning 125 s, in 12 patients with lung tumors, were analyzed by deconvolution modeling to yield tumor blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability (PS) values. CT(p) analyses were undertaken for the reference dataset (i.e., T₁=t₀) with varying T(acq) from 12 to 125 s. This was repeated for shifts in T₁ (±0.5 s, ±1.0 s, ±2.0 s relative to the reference at t₀). Resultant CTp values were plotted against T(acq); values at 30 s, 50 s, 65 s and 125 s were compared using linear mixed model.

RESULTS

All CT(p) parameter values were noticeably influenced by T(acq), with generally less marked changes beyond 50 s, and with no difference in behavior between primary and secondary tumors. Apart from BV, which attained a plateau at approximately 50s, the other three CT(p) parameters did not reach steady-state values within the available 125 s of data, with values at 30 s, 50 s and 65 s significantly different from 125 s (p<0.004). Shifts in T₁ also affected the CT(p) parameters values, with positive shifts having greater impact on CT(p) values than negative shifts.

CONCLUSION

CT(p) parameter values derived from deconvolution modeling can be markedly affected by T(acq), and pre-enhancement set-points. 50 s acquisition may be adequate for BV, but longer than 125 s is probably required for reliable characterization of the other three CT(p) parameters.

Advances and perspectives in lung cancer imaging using multidetector row computed tomography

The introduction of multidetector row computed tomography (CT) into clinical practice has revolutionized many aspects of the clinical work-up. Lung cancer imaging has benefited from various breakthroughs in computing technology, with advances in the field of lung cancer detection, tissue characterization, lung cancer staging and response to therapy. Our paper discusses the problems of radiation, image visualization and CT examination comparison. It also reviews the most significant advances in lung cancer imaging and highlights the emerging clinical applications that use state of the art CT technology in the field of lung cancer diagnosis and follow-up.

Factors influencing local tumor control in patients with neoplastic pulmonary nodules treated with microwave ablation: a risk-factor analysis

OBJECTIVE

This study was performed to evaluate risk factors predictive of local tumor control after microwave ablation of primary and secondary lung malignancies up to 3 cm in maximal diameter.

MATERIALS AND METHODS

The single-antenna microwave ablation treatment of 91 index tumors in 57 patients was studied retrospectively. Time to local tumor progression was monitored on CT scans over the follow-up period. Estimation of overall time to local tumor progression was performed with the Cox regression model. Factors hypothesized to correlate with ablation response included tumor diameter, tumor shape (round or oval versus irregular), clear versus ill-defined tumor margin, adjacency to the pleura, adjacency to bronchi, presence of vessels at least 3 mm in diameter a maximum of 5 mm from the index tumor, energy applied to the index tumor, and the occurrence of cavernous formations after ablation. A logistic regression model was used to correlate the data.

RESULTS

Thirty of 91 (33.0%) index tumors, found in 21 of 57 (36.8%) patients, underwent local progression. The mean time to local tumor progression was 8.3 ± 5.5 months (range 2.1-25.2 months), and the estimated median time to local tumor progression was 22.6 ± 12.4 months. The risk factors that correlated significantly with local tumor progression were a maximal diameter greater than 15.5 mm (p < 0.01), irregular shape of the index tumor (p < 0.01), pleural contact (p = 0.02), and less than 26.7 J/mm(3) applied to the index tumor (p < 0.001). After regression analysis, shape of the index tumor (p = 0.03) and energy deployed per unit volume of the index tumor (p = 0.001) were found to be independent risk factors. Conversely, tumor margin definition (p = 0.06) and proximity of cavernous formations (p = 0.19), juxtatumoral vessels (p = 0.08), and bronchi (p = 0.89) did not affect tumor progression after ablation.

CONCLUSION

The independent predictive factors for local tumor progression in primary and secondary lung neoplasms up to 3 cm in diameter observed in this study were irregular shape of the index tumor and energy application of less than 26.7 J/mm(3) to the index tumor.

Imaging assessment of tumor response: past, present and future

Anatomical response assessment criteria have been in use for decades, with the WHO guidelines being replaced by Response Evaluation Criteria in Solid Tumors (RECIST), updated in 2009 to RECIST 1.1. These methods rely on a change in size of a tumor as the main response criteria, but newer cytostatic agents tend to target tumor function at a molecular level before changing the size of a lesion. Recent modifications, such as the Choi criteria, have improved assessment by taking into account density of tumor, but all of these criteria fail to utilize functional imaging parameters, which are becoming increasingly available, including perfusion CT, perfusion MRI, diffusion-weighted imaging, magnetic resonance spectroscopy, dynamic contrast-enhanced ultrasound and combined PET/computed tomography. Developments in these modalities and standardization of imaging acquisition will help to optimize the next set of response criteria, with inclusion of multiparametric, functional modalities, evaluating tumors at the same molecular level at which they are being targeted by therapeutic agents.