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Year : 2016  |  Volume : 12  |  Issue : 7  |  Page : 171-175

Safety and feasibility within 24 h of discharge in patents with inoperable malignant lung nodules after percutaneous microwave ablation

Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing, China

Date of Web Publication21-Feb-2017

Correspondence Address:
Xiaoguang Li
Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100730
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0973-1482.200608

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 > Abstract 

Context: Minimally invasive interventional therapy is now the more effective treatment strategy for organ-confined malignancy in patients who are poor candidates for surgery. Microwave ablation (MWA) in lung malignancy has been receiving much attention as an effective minimally invasive approach.
Aims: The aim of this study is to evaluate the safety and feasibility within 24 h of discharge of patients treated with percutaneous MWA for inoperable malignant lung nodules, and elucidate the factors predisposing to hospital readmission.
Subjects and Methods: From September 2014 to April 2016, a total of eighty patients with inoperable malignant lung nodules who underwent 24 h of discharge following percutaneous MWA were consecutively enrolled in this retrospective study. Primary endpoints included the rate of short-term admission and procedure-related complications within 30 days of hospital discharge. The secondary outcomes included the rate of technical success and hospital readmission.
Statistical Analysis Used: Student's t- test and Fisher exact test were used to analysis parametric and categorical variables accordingly.
Results: The technical success was achieved in 94% of ablation sessions. Within 24 h of discharge was feasible in 73 cases (91.3%), and 7 (8.7%) required short-term admission. The complication rate was 27.5% (22/80), included the major 40.9% (9/22) and minor 59.1% (13/22) complications. Postoperative adverse event was 17.5% (14/80), these was managed conservatively. The lesion location and puncture technique were associated with an increased need for readmission.
Conclusions: Routine 24 h discharge following percutaneous MWA for malignant lung nodules is safe and feasible, with relatively low complications and few requirements for short-term readmission.

Keywords: Complications, malignant lung nodule, microwave ablation

How to cite this article:
Li B, Wang Z, Zhou K, Gao Q, Li X. Safety and feasibility within 24 h of discharge in patents with inoperable malignant lung nodules after percutaneous microwave ablation. J Can Res Ther 2016;12, Suppl S3:171-5

How to cite this URL:
Li B, Wang Z, Zhou K, Gao Q, Li X. Safety and feasibility within 24 h of discharge in patents with inoperable malignant lung nodules after percutaneous microwave ablation. J Can Res Ther [serial online] 2016 [cited 2022 Jun 26];12, Suppl S3:171-5. Available from: https://www.cancerjournal.net/text.asp?2016/12/7/171/200608

 > Introduction Top

Minimally invasive interventional therapy is now the more effective treatment strategy for organ-confined malignancy in patients who are poor candidates for surgical treatment or who cannot tolerate or refuse surgery. With the improvement of image-guided thermal ablation, it has become a widely accepted modality for the treatment of malignant lung nodules confirmed by pathologic analysis. Thermal destruction may be achieved by locoregional tissue heating (radiofrequency,[1] microwave [2] and laser [3] ablation), and tissue freezing (cryoablation [4]). Among that microwave ablation (MWA) has been receiving much attention as an effective minimally invasive approach, and has significant theoretical advantages over others ablation in the lung.[5] Most of the existing data suggest [2],[3] that MWA could offer an effective method for treating patients with inoperable lung malignancy. However, further investigation of the safety and feasibility of MWA in patients with lung malignancy is needed in clinical practice.

The purpose of this study was, therefore, to assess the safety and feasibility within 24 h of discharge postpercutaneous image-guided MWA for inoperable malignant lung nodules and elucidate the factors predisposing to hospital readmission.

 > Subjects and Methods Top

The study was performed with the approval from the Local Institutional Review Board, and written informed consent was obtained from every patient before treatment. All procedures were performed at our institution between September 2014 and April 2016. The primary aim of this study was to evaluate the rate of short-term admission and procedure-related complications within 30 days of hospital discharge after MWA for inoperative malignant lung nodules. The secondary aims included evaluation of the factors predisposing to technical success and hospital readmission.


From September 2014 to April 2016, we retrospectively and consecutively enrolled patients undergoing MWA at our institution for inoperable malignant lung nodules confirmed by pathologic analysis. All the patients had initial evaluations in outpatient clinics, and the electronic medical and physical records were reviewed. There were 49 men (61%) and 31 women (39%), and ages ranged from 28 to 87 years (mean age, 64.1 years). A total of 80 consecutive patients with 52 primary tumors (65%) and 28 metastases (35%) underwent percutaneous MWA with computed tomography (CT) guidance. The patient demographics and tumor characteristics is shown in [Table 1].
Table 1: Patient demographics and tumor characteristics (80 - patients and 100 tumors)

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The inclusion criterion was a malignant lung nodule considered suitable for MWA by a multidisciplinary team comprising physicians, surgeons, oncologists, and interventional radiologists, all with expertise in lung tumor management. All patients were with histologically proved nonsmall cell lung cancers or metastases, and with significant comorbidities or refusal to surgery. The exclusion criteria for patient treatment included patients with any tumor longest diameter >3 cm, cardiopulmonary dysfunction (forced expiratory volume [FEV] <1 L, FEV1% <50%, MVV <50%, New York Heart Association Class III), international normalized ratio >1.4 or platelet count <50 × 109/L, uncontrolled diabetes mellitus or hypertension.

Microwave ablation procedure

Patients who intended to undergo MWA were fasted for 8 h, water deprivation 2 h before the procedure, and routine imaging and laboratory examinations were performed within 2 weeks. All patients received a preprocedural medication regimen, which included intravenous administration of 8 mg of ondansetron, 5 mg of dexamethasone, 2U of hemocoagulase, and intramuscular injection of 10 mg morphine. Patients were monitored with heart rate, blood pressure, oxygen saturation, and continuous electrocardiogram during the procedure. The MWA was performed with routine local anesthesia, which was achieved by subcutaneous injection of 1% lidocaine.

All the procedures were performed by two interventional radiologists, each with >5 years of experience with thermal ablation, and a technician, and a nurse in a hospital CT room. The most appropriate approach to plan patient position, site of puncture, and route of antenna insertion was selected on the basis of the location of the tumor at preprocedural diagnostic work-up, including chest unenhanced and contrast material-enhanced CT images. Among that the path of the antenna track for treatment was planned to avoid vessels, bronchi, and fissures. MWA was performed using a MWA/resection system (Surblate System, Vision Medical, American) operating at 2.45 GHz, allowing 5–120W to be delivered to the tumor through a 17-gauge internally water-cooled antenna. MWA was performed percutaneously with one antenna introduced into the nodule under the CT guidance (Somatom Perspective 64; Siemens, Erlangen, Germany). The CT scanning parameters were as follows: 110 kVp, 120 mA, and 5 mm intervals. Power of 40–60W was applied for 3–5 min for nodules 2 cm or smaller; for nodules >2 cm and <3 cm, this was repeated two times after repositioning of the antenna. [Table 2] summarizes the MWA treatment algorithm used at our institution for patients. Immediate postablation unenhanced CT was performed in all cases to identify MWA margins (at least >0.5–1.0 cm of tumor coverage). Satisfactory ablation was defined by the ground-glass opacification surrounding the tumor on CT. If the tumor was not covered completely by the ablation coverage, further therapy was discussed. Chest X-ray examination was performed at 6 h after the procedure to show the postoperative air volume in the thorax or the delayed pneumothorax occurred.
Table 2: Microwave ablation treatment algorithm

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Patients were observed in Intensive Care Unit for 24 h after ablation, during which they received serial assessment of vital signs and were evaluated for signs of adverse events, including fever, pain, and hemoptysis. A chest radiograph was obtained in all patients at 24 h after ablation to assess for periprocedural complications (pneumothorax and pleural effusion). If in clinically stable condition within 24 h, patients were discharged home the following day. Every patient with overtly unstable clinical signs was instructed to visit the emergency department for further observation and management after discharge from hospital. At 30 days after ablation, patients were seen in the clinic to assess for clinical outcomes and complications. These investigations were performed to evaluate the rate of short-term admission and periprocedural complications within 1 month of hospital discharge.

Complication assessment

All the complications in the periprocedural period were assessed based on the location, size, number, and histologic type of the tumors treated, and defined based on the Society of Interventional Radiology classification of complications. The definition of major complication was an event that led to substantial morbidity and disability, requiring therapy and minor hospitalization, increasing the level of care, or resulted in hospital admission or substantially lengthened hospital stay.[6],[7] All other complications were defined as minor. Adverse events included pain, the postablation syndrome and asymptomatic pleural effusions.

Statistical analysis

Statistical analysis was performed using SPSS statistical software (version 18.0; SPSS Inc., Chicago, IL, USA). Differences between the means of the continuous variables were tested using Student's t-test. Fisher exact tests were used to analysis parametric and categorical variables. For all statistical analyses, P < 0.05 was considered to indicate a statistically significant difference.

 > Results Top

Between September 2014 and April 2016, 100 malignant lung nodules in 80 patients were treated in 93 sessions. Overall, there were 49 men (61%) and 31 women (39%), and their ages ranged from 28 to 87 years (mean age, 64 years with a standard deviation [SD], ±12.6). A total of 80 consecutive patients with 52 primary tumors (65%) and 28 metastases (35%) underwent percutaneous MWA with CT guidance. The mean index size of the nodules was 2.0 cm (SD, ±0.63). Of 80 patients, 64 were diagnosed single lesion (80%), 12 double lesions (15%), and 4 triple lesions (5%). The patient details and tumor characteristics is given in [Table 1].

Intent-to-treat technical success was achieved in 94 of 100 nodules (94%). There were no procedure-related mortalities. The median ablation time was 4 min (range, 3–5 min), and the mean ablation time per nodule was 4.4 min (SD, ±0.9). When analyzed by tumor size, the number of microwave antenna insertions was one for nodules <2.0 cm in diameter, whereas the number of antenna passes was two for nodules >2.0 cm and <3.0 cm in diameter. The results of MWA treatment, according to patient characteristics and tumor sizes, are summarized in [Table 3].
Table 3: Microwave ablation variables

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The treatment of six nodules in six patients was aborted or deemed incomplete because of overly intraprocedural complications. Intraprocedural major complications of pneumothorax occurred in three patients, all required placement of a chest tube. Two patients experienced intolerable pain during the ablation procedures, not relieved by intravenous injection of 5 mg morphine sulfate. Another patient with asymptomatic air embolism confirmed with a few air in thoracic aorta and heart seen on CT immediately after introduction of the microwave antenna. All the six patients recovered completely without permanent morbidity.

Patients were discharged within 24 h in 73 of 80 cases (91.3%), and 7 of 80 cases (8.7%) required short-term admission due to intra- and post-operative complications. Three patients (3.7%) were readmitted for periprocedural complications within 30 days of discharge, neither of whom had immediate complications identified during the 24 h observation period. One patient was readmitted 11 days after discharge with mild subcutaneous emphysema surrounding the puncture point of MWA. Appropriate antibiotic and analgesic treatment were given to the patient. Another two patients were readmitted to the emergency department 1 week after discharge with lung abscess complicated by dyspnea and high fever. The local abscess was drained percutaneously with CT guidance, and the patients were treated with intravenous antibiotics and discharge 5 days and 9 days later, respectively.

The rate of procedure-related complications was 27.5% (22/80), included the major 40.9% (9/22) and minor 59.1% (13/22) complication. There were nine major complications including severe pneumothorax 33.3% (3/9), severe pain 22.2% (2/9), air embolism 11.1% (1/9), lung abscess 22.2%, (2/9) and intercostal artery injury 11.1% (1/9). The remaining 13 of the 22 complications were classified as minor, and included small pneumothorax 76.9% (10/13), subcutaneous emphysema 7.7% (1/13), and pleural effusion 15.4% (2/13). Adverse events included hemoptysis 8.7% (7/80), fever 2.5% (2/80), and chest pain 6.2% (5/80). There were no cases of permanent adverse sequelae or mortality. A summary of MWA complications are shown in [Table 4].
Table 4: Microwave ablation complications

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 > Discussion Top

Lung cancer is still now the leading cause of cancer death among men in terms of both incidence and mortality; among women, it has been became the third highest incidence and is following breast cancer in mortality. In 2012, there were 1.82 million new cases in worldwide, 1.56 million deaths occurred as a result of lung cancer, representing 19.4% of all deaths from cancer.[8] In addition, the lungs are the second most common organ for metastases from solid tumors. The recurrence rate is >80% at 2 years after surgery defined as the gold standard. The rate of recurrence after 5 years is 9%.[9]

Percutaneous CT guided thermal ablation is a widely accepted locoregional treatment for inoperable solid tumors. Dupuy et al. first reported the use of radiofrequency ablation (RFA) for treatment of lung cancer in 2000.[10] Since that report, most of the existing data suggested the efficacy for thermal ablation of lung and thoracic malignancies in selected patients.[11] The different energy modalities available for tumor ablation include RFA, MWA, laser ablation, and cryoablation. In comparison with RFA, MWA creates higher temperature in tissue, is a more rapid therapy, and creates larger ablation zones in ex vivo and in vivo experiment.[12] For malignant lung nodules (lesion diameter <3 cm) confirmed by pathologic analysis, percutaneous MWA has been shown to confer survival benefit in patients with inoperable disease who are not responsive to chemoradiotherapy. However, little is known about the safety and feasibility within 24 h discharge of patients with inoperable lung malignant nodules after MWA. The advantages of within 24 h discharge after MWA include lowering cost and reducing the risk of nosocomial infections. Evaluation of the safety and feasibility within 24 h discharge is particularly conductive to gain wider adoption and application in clinical practice.

The results of this study confirmed that patients undergoing percutaneous MWA for the treatment of lung tumors can be managed safely and feasible by using within 24 h discharge strategy. There was 3.7% (3/80) of readmission for complications within 30 days following 24 h discharge, and nearly all the complications were seen in the observation period within 24 h post the ablation. The follow-up chest radiography during the 6 h postoperative observation period was useful in giving effective management for those patients with higher risk of late complications. All the nine patients (11.3%) with major complications needed a short-term admission, and then given symptomatic treatments in a few day of recovery. The most frequent complication in this study was pneumothorax, a total of 13 patients (16.2%) developed pneumothorax after lung ablation. Severe pneumothorax occurred in three of eighty patients (3.7%). All of the patients requiring chest tube insertion received 5–6 days of further treatment for this complication and discharged without obvious sequelae. This frequency was similar to previous reports for MWA.[13] In this study, emphysema and tumor location were apparently closely related with chest tube placement for pneumothorax. Lesion near the pleura (<1 cm), the distance of traversed lung parenchyma of puncture, and the number of insertions of microwave antenna can be the significant risk factors causing procedure-related complications. Comparison with RFA, MW ablation makes it easier to generate the unintentional thermal damage to nontargeted areas. Chest pain and pleural effusion are the common complications even acting as main causes of procedure-related thermal damage. Therefore, based on these data, the rate of readmission and periprocedural complications within 24 h discharge were acceptable.

The present study had several limitations, which include that the study did not have long-term follow-up for adverse events or survival benefit in patients, and did not intent to assess the treatment effect of thermal ablation. This study was a nonrandomized, single-institution, retrospective study within a single cohort, there were underlying biases in patient selection caused by referral patterns, and hence the results should be perceived as preliminary. In addition, all tumor treated was <3 cm in diameter and the patient were in different clinical conditions, so the results regarding the safety and feasibility within 24 h discharge may not be suitable for large tumors and every patient.

Despite its limitations, this study supports within 24 h discharge after MW ablation treatment for patients with inoperable malignant nodule as safe and feasible, and with relatively few complications. Using of this discharge strategy can achieve a low rate of short-term admission and visitation to the emergency department. Further studies are needed to assess the therapeutic effect and complication within 24 h discharge for ablation of larger tumors.

 > Conclusion Top

Percutaneous microwave ablation is the safe and feasible therapy for inoperable malignant lung nodules within 24 h discharge, and with relatively low complicaitons and few requirements for short-term readmission.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

 > References Top

Simon CJ, Dupuy DE, Dipetrillo TA, Safran HP, Grieco CA, Ng T, et al. Pulmonary radiofrequency ablation: Long-term safety and efficacy in 153 patients. Radiology 2007;243:268-75.  Back to cited text no. 1
Carrafiello G, Laganà D, Mangini M, Fontana F, Dionigi G, Boni L, et al. Microwave tumors ablation: Principles, clinical applications and review of preliminary experiences. Int J Surg 2008;6 Suppl 1:S65-9.  Back to cited text no. 2
Vogl TJ, Naguib NN, Lehnert T, Nour-Eldin NE. Radiofrequency, microwave and laser ablation of pulmonary neoplasms: Clinical studies and technical considerations – Review article. Eur J Radiol 2011;77:346-57.  Back to cited text no. 3
Zargar H, Atwell TD, Cadeddu JA, de la Rosette JJ, Janetschek G, Kaouk JH, et al. Cryoablation for small renal masses: Selection criteria, complications, and functional and oncologic results. Eur Urol 2016;69:116-28.  Back to cited text no. 4
Lu Q, Cao W, Huang L, Wan Y, Liu T, Cheng Q, et al. CT-guided percutaneous microwave ablation of pulmonary malignancies: Results in 69 cases. World J Surg Oncol 2012;10:80.  Back to cited text no. 5
Goldberg SN, Grassi CJ, Cardella JF, Charboneau JW, Dodd GD, Dupuy DE, et al. Image-guided tumor ablation: Standardization of terminology and reporting criteria. J Vasc Interv Radiol 2005;16:765-78.  Back to cited text no. 6
Rose SC, Dupuy DE, Gervais DA, Millward SF, Brown DB, Cardella JF, et al. Research reporting standards for percutaneous thermal ablation of lung neoplasms. J Vasc Interv Radiol 2009;20 7 Suppl: S474-85.  Back to cited text no. 7
Stewart BW, Wild CP. World Cancer Report 2014. Lyon: IARC Press; 2014. p. 545-56.  Back to cited text no. 8
Choi PJ, Jeong SS, Yoon SS. Prognosis of recurrence after complete resection in early-stage non-small cell lung cancer. Korean J Thorac Cardiovasc Surg 2013;46:449-56.  Back to cited text no. 9
Dupuy DE, Zagoria RJ, Akerley W, Mayo-Smith WW, Kavanagh PV, Safran H. Percutaneous radiofrequency ablation of malignancies in the lung. AJR Am J Roentgenol 2000;174:57-9.  Back to cited text no. 10
Alberti N, Buy X, Frulio N, Montaudon M, Canella M, Gangi A, et al. Rare complications after lung percutaneous radiofrequency ablation: Incidence, risk factors, prevention and management. Eur J Radiol 2016;85:1181-91.  Back to cited text no. 11
Yu J, Liang P, Yu X, Liu F, Chen L, Wang Y. A comparison of microwave ablation and bipolar radiofrequency ablation both with an internally cooled probe: Results in ex vivo and in vivo porcine livers. Eur J Radiol 2011;79:124-30.  Back to cited text no. 12
Zheng A, Wang X, Yang X, Wang W, Huang G, Gai Y, et al. Major complications after lung microwave ablation: A single-center experience on 204 sessions. Ann Thorac Surg 2014;98:243-8.  Back to cited text no. 13


  [Table 1], [Table 2], [Table 3], [Table 4]


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