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 » Introduction
 » Patients and Methods
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  Table of Contents  
Year : 2015  |  Volume : 52  |  Issue : 6  |  Page : 91-95

Computed tomography-guided percutaneous microwave ablation treatment for lung metastases from nasopharyngeal carcinoma

Department of Image-guided Minimally Invasive Therapy, State Key Laboratory of Oncology in South , Sun Yat-Sen University Cancer Center, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China

Date of Web Publication24-Dec-2015

Correspondence Address:
W Fan
Department of Image-guided Minimally Invasive Therapy, State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Collaborative Innovation Center of Cancer Medicine, Guangzhou
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0019-509X.172521

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 » Abstract 

Background: The objective of this retrospective study was to evaluate the safety and efficacy of percutaneous microwave ablation (MWA) for treating lung metastases from nasopharyngeal carcinoma (NPC). Patients and Methods: From December 2012 to November 2014, 17 patients (15 males, and two females, averaged 45.7 years old) with lung metastases from NPC accepted computed tomography (CT)-guided percutaneous MWA. The average number of lung metastases was 1.7 (range: 1–4), and the biggest tumor diameter was 4.2 cm (range: 0.8–4.2 cm). Nineteen nodules located in the right lung and 10 nodules located in the left lung. A total of 29 ablation sites were performed to 29 lung metastases in 22 MWA sessions. Postoperative assessments of complete tumor necrosis rate, safety, local tumor progression, and survival period were carried out. Results: Of the 29 lesions, complete response was achieved for 27 lesions; residual tumor was found in one lesion 3 months postoperatively; and another lesion was found enlarged 3-month postoperatively with obvious enhancement. Four patients had a small amount of postoperative parenchyma bleeding and two patients had a small amount of pneumothorax. Six months after MWA treatment, new metastatic lesions appeared in six patients, five patients had new metastatic lesions inside the lung, and the other patient had metastatic lesions in the thoracic vertebra. The time for the appearance of new pulmonary metastases for the five patients was 4–20 months, averaged 7.2 months. Conclusion: CT-guided MWA is a promising treatment alternative for local tumor control in selected patients with lung metastases from NPC.

Keywords: Ablation, metastases, microwave, nasopharyngeal carcinoma, therapeutic effects

How to cite this article:
Qi H, Wan C, Li X, Zhang L, Song Z, Fan W. Computed tomography-guided percutaneous microwave ablation treatment for lung metastases from nasopharyngeal carcinoma. Indian J Cancer 2015;52, Suppl S2:91-5

How to cite this URL:
Qi H, Wan C, Li X, Zhang L, Song Z, Fan W. Computed tomography-guided percutaneous microwave ablation treatment for lung metastases from nasopharyngeal carcinoma. Indian J Cancer [serial online] 2015 [cited 2021 Jun 22];52, Suppl S2:91-5. Available from:

 » Introduction Top

Nasopharyngeal carcinoma (NPC) is the most common malignancy in South China, with the highest incidence rate in Guangdong Province.[1],[2] The incidence of distant metastases from NPC was 17–54% in various reports, of which, lung, bone, liver, and distant lymph nodes are the most common sites for distant metastases.[3],[4] With the advancement of radiotherapy technology, such as three-dimensional conformal radiotherapy and intensity modulated radiotherapy, there is a high local control rate for NPC, making distant metastases of NPC the main causes for treatment failure.[5],[6] Among the NPC patients with distant metastases, lung metastases were most common.[7] Although patients with lung metastases have longer progression-free survival period and overall survival (OS) period, compared to metastases in other organs;[8] it is found that radiofrequency ablation (RFA) and other minimally invasive treatment modalities have achieved good results by extending the survival period for patients in recent studies.[9],[10],[11] Thus, it is necessary to have more active treatments for these patients.

Microwave ablation (MWA) is a recently developed thermal ablation technology for treating tumors, and it has been widely applied in lung cancer, lung metastases, kidney cancers, etc.[12] There has been more and more reports on the application of MWA for treating lung cancers and lung metastases;[13],[14],[15],[16] however, as far as we know, there is no report on the therapeutic effects of MWA for treating lung metastases from NPC. We conducted a retrospective study using the clinical data of the 17 patients who underwent MWA for lung metastases from NPC during December 2012 to November 2014, so as to evaluate the value of MWA treatment for lung metastases from NPC.

 » Patients and Methods Top

Study design

This retrospective study was approved by the Institutional Review Board of Sun Yat-Sen University Cancer Center. Detailed explanation about the ablation process, possible complications, and expected results were explained to all patients before the treatment. All the patients agreed to the treatments and signed the consent form for receiving the treatment. The purpose of this study was to evaluate the value of MWA treatment for lung metastases from NPC. All the patients must meet the following conditions for MWA treatment: (1) pathologically diagnosed as NPC; (2) the patients performance-status score (the ECOG score) during treatment ranged from 0 to 1; (3) no more than five metastatic tumors inside the lung; (4) chemotherapy failure or refusal for chemotherapy due to toxicity for lung metastases; (5) the therapeutic evaluation of primary lesion and regional lymph nodes was determined to be complete remission; (6) lung metastases were more than 1 cm away from the main bronchi, pulmonary artery and main branches, heart, diaphragm, thoracic aorta, and other organs; (7) there was no evidence of metastases outside the lung; (8) all treatments were performed in our hospital.

Patient data

Seventeen patients with lung metastases from NPC (15 males and two females, aged 28~65 years, mean age was 45.7 years) received computed tomography (CT)-guided MWA treatment at Sun Yat-Sen University Cancer Center during December 2012 to November 2014. Of which, two patients were diagnosed as lung metastases from NPC through lung lesion excision and the rest 15 patients were clinically diagnosed as lung metastases from NPC, according to the cancer history and clinical findings.

Treatment schedule for metastases

Treatment history

All patients underwent initial radical radiotherapy treatment, with 64–76 Gy cumulative radiation dose for the primary tumor and 50–67 Gy cumulative radiation dose at the neck regional lymph nodes. Of which, 14 patients received neoadjuvant chemotherapy or adjuvant chemotherapy, with cisplatin alone or cisplatin plus 5-Fu plan. The postoperative evaluation for the primary tumor and regional lymph nodes was complete remission.

After the diagnosis of lung metastases from NPC, five patients refused chemotherapy and surgery and chose MWA as their first-line therapy. There were 10 patients who accepted systemic cytotoxic chemotherapy, but failed to have control for the lung metastases, thus conducted MWA treatment. There are two patients, who accepted surgical removal, but had recurrence of lung metastases, refused to have surgical removal again, and then accepted MWA treatment.

Procedure planning

All the patients were confirmed by imaging examinations, such as nasopharyngeal magnetic resonance imaging and chest CT. They had no recurrences of primary nasopharyngeal lesions and they had metastases inside the lung only, but no distant metastases in other parts or organs. All the patients underwent preoperative laboratory-related tests, including routine blood test, blood biochemistry, and coagulation test.


All MWAs were performed in the ablation dedicated CT room. All operational processes were carried out with intravenous anesthesia (intravenous midazolam and propofol), and the anesthetist was responsible for monitoring vital signs (blood pressure, heart rate, oxygen saturation, etc.). All treatments were conducted using CT guidance. Two doctors, with more than 10 years' experience of ablation, completed all the operations. The patients were usually in the supine, lateral, or prone positions depending on the tumor locations determined by preoperative imaging examinations. Puncture point, angle, and depth were determined after the CT scan for the lung metastases. After selecting the puncture point, 2% lidocaine was used for local anesthesia, and a small incision was made. A 16 G microwave antenna was gradually inserted into the internal tumor along the predesigned angle and depth. CT scan was used again and the antenna's angle and depth were adjusted, when necessary, to ensure whether ablation antenna was located in the right position inside the tumor.

For MWA, we used a commercially available 2450 MHz system (FORSEA; Qinghai Microwave Electronic Institute, Nanjing, China) and a 16-gauge cooled-shaft antenna with a peristaltic pump that re-circulated chilled saline solution to maintain a mean shaft temperature of 10°C ± 2°C.

The MWA protocol depended on the recommendations by the manufacturer and our experience about MWA for primary lung tumors in the past, so as to achieve complete response [Table 1]. For tumors with diameters >3 cm, superimposed ablation was used to make the ablation area cover the tumor completely. The ablation zone: the ground glass region should at least exceed 0.5~1 cm from the edge of the lesion on chest CT scan. During the puncture and ablation process, CT scan was used at any time depending on the patient's situation to evaluate the necrosis after ablation, as well as to observe any complications, such as bleeding, pneumothorax, and hemothorax. For patients with metastatic tumors in both lungs, one side of the lung often underwent MWA treatment 1 week later after the other side of the lung and only if the previous MWA did not have complications, such as pneumothorax and hemothorax, so as to avoid bilateral pneumothorax, hemothorax, which are life-threatening.
Table 1: Tumor characteristics and treatments for all patients

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Patient follow-up

We did follow-up for all patients who underwent MWA treatments. Routine contrast-enhanced CT was performed 1 month after treatment and every 3 months thereafter to determine if the lesion had achieved complete ablation, any residues or recurrence, and to find out if there were any metastases in other organs. The interval time for CT scan was adjusted based on the primary lesion and the patients' clinical conditions.

During the follow-up, if no localized irregular enhancement of the lesions were shown on routine contrast-enhanced CT after MWA, it was considered as complete response and success for MWA technology. A thin symmetric rim of peripheral enhancement of <5 mm wide, observed up to 6 months after ablation was considered a sign of benign peritumoral enhancement. Irregular focal soft-tissue enhancement (>15 HU) was considered to be a sign of residual or recurrent disease.

 » Results Top

Clinical evaluation of the therapeutic effects and patient follow-up

Before MWA treatment, 10 patients had single lung metastasis [Figure 1]; three patients had two lesions; three patients had three lesions; and one patient had four lung metastatic tumors; of which, six patients had bilateral lung metastases. A total of 29 metastatic lesions were found in the 17 patients, of which 19 lesions were located in the right lungs and 10 lesions in the left lungs. There was no evidence for metastases outside the lung in all the patients.
Figure 1: A 33-year-old male patient with left lung metastasis after chemoradiotherapy for NPC; the largest lung lesion diameter was 1.4 cm; microwave ablation was given with 60 W/8 min. The tumor gradually shrunk with no enhancement during the follow-ups. (a) Before microwave ablation: left lung lesion with the largest diameter of about 1.4 cm (white arrow); (b) during the microwave ablation treatment: microwave ablation needle was punctured into the parenchyma of the lung nodule (white arrow); (c) right after microwave ablation: the ablation zone underwent exudative change (white arrow); (d, d') 3 months after microwave ablation: lesion appeared as flaky-shaped pulmonary consolidation with no enhancement (white error); (e) 6 months after microwave ablation: flake-shape consolidation image was significantly smaller than before (white arrow); (f) 21 months after microwave ablation: flake-shape consolidation image was obviously shrunk (white arrow)

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We did follow-ups for all the patients. The average follow-up period after MWA treatment was 14 months (range: 3~24 months). The average interval time from diagnosis of lung metastases from NPC to the application of MWA treatment was 6.6 months (range: 0 ~44 months). The number of metastatic tumors in the patients was 1~4 (averaged 1.7 tumors). The largest diameter of the tumor was 4.2 cm. A total of 29 ablation sites were performed to 29 lung metastases in 22 MWA sessions. Twenty-seven lesions had achieved complete response and had no localized residue or recurrence in the follow-up period. As to the two remain lesions, one was found localized enhancement in the CT scans 3 months postoperatively, another lesion appeared accretion with significant enhancement during the follow-ups.

Local control and new recurrence

After the MWA treatment, six patients had new metastases, of which five patients had new metastases inside the lung and the other patient had thoracic vertebral metastases 1 year postoperatively. Of the five patients who had new lung metastases, the time for new lung metastases was 4–20 months, averaged 7.2 months. By the time when this article was written, 11 patients had no metastases anywhere after the MWA treatments.

Adverse reactions and complications

Two patients had small amounts of pneumothorax during the MWA, which were absorbed after observation, all without chest tube drainage. Four patients had a small amount of parenchyma bleeding during the ablation treatment. The remaining patients had no significant complications.

 » Discussion Top

Among the head and neck cancer, NPC has the highest tendency for distant metastases. Combined distant metastases often lead to treatment failure, leaving patient with poor prognosis and it becomes the major cause of death.[3],[17] The incidence rate of distant metastases ranges from 17% to 54%.[14] Palliative combined chemotherapy based on platinum is the standard treatment for metastatic NPC. Among the distant metastases, lung metastases have the best prognosis;[18] thus, it is necessary to have active treatments for lung metastases from NPC. Recent studies have found that surgical resection of the lung metastases can extend the survival periods for NPC patients.[9],[10] The therapeutic effects of MWA for some lesions were comparable to surgical resection, but MWA is more minimally invasive and has higher repeatability. The success of MWA treatment for primary tumors and lung metastatic tumors [19],[20],[21] in recent years made us to consider applying this technique to patients with lung metastases from NPC. We retrospectively reviewed our experience for using MWA to treat patient with lung metastases from NPC, and the results indicated that for the selected patients with lung metastases from NPC, MWA was a safe and effective treatment alternative.

In the previous study, Wolf et al.[13] reported the application of MWA in 50 patients of primary lung tumors and lung metastases, it had achieved 67% local control rate in 1 year, mean time to first recurrence was 16.2 months, and the 1-year survival rate of 83%, 2-year survival of 73%, and 3-year survival of 61% for all patients. Yang et al.[16] conducted MWA in 47 patients with inoperable nonsmall cell lung carcinoma at stage I, and the local control rates at 1, 3, 5 years after MWA were 96%, 64%, and 48%, respectively. The median cancer-specific and median OS were 47.4 and 33.8 months, respectively. The OS rates at 1, 2, 3, and 5 years after MWA were 89%, 63%, 43%, and 16%, respectively. In our study, the local control rate at 1 year was 88.2%, which is consistent with the studies in the past.

There are reports about applying RFA for metastases from NPC in recent years. Pan et al. study suggested that RFA prolongs the OS period for patients with lung metastases from NPC when compared to patients without RFA treatment.[11] In their study, the OS period was 77.1 months for patients with lung metastases from NPC and accepted RFA when compared to the survival periods of 32.4 months for patients without RFA treatment. In terms of survival rate, there was no significant difference between RFA and surgical resection for patients. Comparing to surgical resection, thermal ablation is less invasive, has higher repeatability and safety, patients had faster recovery time, and it has more advantages for patients with lesions in different lung lobes and bilateral lungs.

Comparing to RFA, MWA has the following advantages: continuous higher intratumoral temperatures, faster temperature rise rate, larger ablation volume, and shorter ablation time.[23] Moreover, MWA has more advantages in lung tumor ablation. This is because energy transfer in RFA depends on the current conduction within the tissues, restricted to the effects of tissue impedance and carbonization. The lung tissue has high gas content, leading to high impedance, which is not good for radiofrequency energy delivery. However, the energy delivery for MWA does not rely on current conductance, and tissue impedance or carbonization have small impacts on MWA, thus energy delivery for MWA was better than RFA.[22] More randomized and comparative studies with large sample size are needed to determine if MWA has more advantages for local control rate and to extend the survival period for patients.

In the past reports, the most common complications for percutaneous MWA were pneumothorax, hemorrhage, pleural effusion, subcutaneous emphysema, and tumor metastases along the needle tract.[24] Of which, pneumothorax had the highest incidence rate, which is about 20% and some need closed drainage with chest tubes. In our study, two patients had a small amount of pneumothorax, but was resorbed after observation, without chest tube drainage. A small amount of parenchyma bleeding occurred in four patients after ablation, and all were without hemothorax after conservative therapy. The remaining patients had no significant complications. The low complication rate owed to the following tips:first, we chose the optimal puncture path to reduce the damage of pulmonary parenchyma as far as possible; second, we tried our best to reduce the needle adjustment times; third, when adjusting the needle, the pinpoint was not allowed retreating out of the pleura.

Our preliminary results show that MWA is a safe treatment method, and it provides an alternative for patients with lung metastases from NPC, with a good local tumor control rate and improve the survival period for these patients. However, this study has its limitations:first of all, the sample size was too small and the follow-up period was short; in addition, our study was only a retrospective study. We are looking for prospective, randomized, and comparative research with increased sample size and extended follow-up period, comparing the MWA to surgical resection for lung metastases from NPC in the future, so as to further confirm the real benefit of MWA in improving the survival for patients with lung metastases from NPC.

 » References Top

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Ahmad A, Stefani S. Distant metastases of nasopharyngeal carcinoma: A study of 256 male patients. J Surg Oncol 1986;33:194-7.  Back to cited text no. 3
Huang CJ, Leung SW, Lian SL, Wang CJ, Fang FM, Ho YH. Patterns of distant metastases in nasopharyngeal carcinoma. Kaohsiung J Med Sci 1996;12:229-34.  Back to cited text no. 4
Lee N, Xia P, Quivey JM, Sultanem K, Poon I, Akazawa C, et al. Intensity-modulated radiotherapy in the treatment of nasopharyngeal carcinoma: An update of the UCSF experience. Int J Radiat Oncol Biol Phys 2002;53:12-22.  Back to cited text no. 5
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Fandi A, Bachouchi M, Azli N, Taamma A, Boussen H, Wibault P, et al. Long-term disease-free survivors in metastatic undifferentiated carcinoma of nasopharyngeal type. J Clin Oncol 2000;18:1324-30.  Back to cited text no. 7
Hui EP, Leung SF, Au JS, Zee B, Tung S, Chua D, et al. Lung metastasis alone in nasopharyngeal carcinoma: A relatively favorable prognostic group. A study by the Hong Kong Nasopharyngeal Carcinoma Study Group. Cancer 2004;101:300-6.  Back to cited text no. 8
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Pan CC, Wu PH, Yu JR, Li W, Huang ZL, Wang JP, et al. Comparative survival analysis in patients with pulmonary metastases from nasopharyngeal carcinoma treated with radiofrequency ablation. Eur J Radiol 2012;81:e473-7.  Back to cited text no. 11
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Wolf FJ, Grand DJ, Machan JT, Dipetrillo TA, Mayo-Smith WW, Dupuy DE. Microwave ablation of lung malignancies: Effectiveness, CT findings, and safety in 50 patients. Radiology 2008;247:871-9.  Back to cited text no. 13
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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. 15
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Li X, Wang J, Li W, Huang Z, Fan W, Chen Y, et al. Percutaneous CT-guided radiofrequency ablation for unresectable hepatocellular carcinoma pulmonary metastases. Int J Hyperthermia 2012;28:721-8.  Back to cited text no. 21
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Dodd GD 3rd, Dodd NA, Lanctot AC, Glueck DA. Effect of variation of portal venous blood flow on radiofrequency and microwave ablations in a blood-perfused bovine liver model. Radiology 2013;267:129-36.  Back to cited text no. 23
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  [Figure 1]

  [Table 1]

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