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Year : 2021  |  Volume : 17  |  Issue : 3  |  Page : 803-807

Ultrasound-guided percutaneous microwave ablation of bilateral renal cell carcinomas: Focus upon safety and efficacy

1 Department of Interventional Ultrasound, Chinese PLA Medical School, Beijing; Department of Urology Surgery, Baotou Fourth Hospital, Baotou, Inner Mongolia, China
2 Department of Interventional Ultrasound, Chinese PLA Medical School, Beijing, China

Date of Submission31-Dec-2020
Date of Decision02-Apr-2021
Date of Acceptance21-Apr-2021
Date of Web Publication9-Jul-2021

Correspondence Address:
Jie Yu
Department of Interventional Ultrasound, Chinese People's Liberation Army General Hospital, No. 28 Fuxing Road, Haidian District, Beijing 100853
Xiaoling Yu
Department of Interventional Ultrasound, Chinese People's Liberation Army General Hospital, No. 28 Fuxing Road, Haidian District, Beijing 100853
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcrt.jcrt_1906_20

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 > Abstract 

Objective: To retrospectively review the safety and efficacy of ultrasound (US)-guided percutaneous microwave ablation (MWA) of bilateral renal cell carcinomas (BRCCs).
Patients and Methods: In this study, eight patients of BRCCs with 20 lesions seen from November 2012 to October 2018 were enrolled retrospectively. The patients were treated with US -guided percutaneous MWA and were followed up with contrast-enhanced US and computed tomography or magnetic resonance imaging.
Results: Technical success was achieved 20 tumors. The 18 lesions were performed to ablate 90%; 2 lesions were repeated because of detecting residual ablated tumor. Except six patients were noted fever, no severe complications occurred. The median follow-up time was 24 months (range 7–59 months). Among the eight patients, there was no local tumor recurrence in 6 of 8 completely ablated tumor lesions. One patient was retreated by MWA 6 months after ablation, and another was retreated after 19 months due to local tumor recurrence. No patients have obvious change of renal function and lost their life.
Conclusion: US-guided percutaneous MWA is a beneficial treatment for BRCC.

Keywords: Bilateral renal cell carcinomas, microwave ablation, ultrasonography

How to cite this article:
Zhang R, Qi E, Liang P, Cheng Z, Tan S, Han Z, Liu F, Yu J, Yu X. Ultrasound-guided percutaneous microwave ablation of bilateral renal cell carcinomas: Focus upon safety and efficacy. J Can Res Ther 2021;17:803-7

How to cite this URL:
Zhang R, Qi E, Liang P, Cheng Z, Tan S, Han Z, Liu F, Yu J, Yu X. Ultrasound-guided percutaneous microwave ablation of bilateral renal cell carcinomas: Focus upon safety and efficacy. J Can Res Ther [serial online] 2021 [cited 2021 Jul 29];17:803-7. Available from: https://www.cancerjournal.net/text.asp?2021/17/3/803/321022

 > Introduction Top

Renal cell carcinomas (RCCs) account approximately 3% of all cancers, with the highest incidence occurring in Western countries.[1] Compared to unilateral RCC, bilateral RCCs (BRCCs) represent uncommonly 1%–5% of kidney cancer were diagnosed.[2] BRCCs offer challenging therapeutic dilemmas, balancing the need for long-term tumor control and preserving maximal renal functions, since the vital function of kidneys. Because of partial radical nephrectomy of both kidneys would result in life-long hemodialysis,[3] minimizing treatment-related loss of renal function treatment has received increased emphasis. Given the surgical constraints, image-guided thermal ablation, such as percutaneous microwave ablation (MWA), radiofrequency ablation (RFA), and cryoablation, has showed good safety and efficacy on local tumor control.[4] In addition, it has increasing popularity in recent years due to less invasive and low incidence of major complications in the treatment of BRCCs.[5],[6]

The current literature shows that the major advantages of MWA over RFA are less influence by the heat-sink effect[7] of blood vessels adjacent to or embedded in the ablation zone and a faster ablation procedure. In addition, MWA directly destroys a large lesion near the antenna in a short time and energy propagation is rarely limited by tissue desiccation and charring.[8] The advantages of MWA make this method a good treatment option even in inoperable tumors with lower morbidity and mortality and the cost is comparable to that of surgery.[9],[10] Ultrasound (US) guided percutaneous MWA is now a well-established technique for treating small renal tumors with MWA techniques and devices significant improvement.[6],[11] However, US-guided percutaneous MWA study addressing BRCs is still lacking. In this study, we aimed to evaluate the safety and clinical outcomes and supply the evidence supporting the use of US-guided percutaneous MWA in the treatment of patients with BRCCs.

 > Patients and Methods Top


All cases of BRCCs treated with US-guided percutaneous MWA at the Department of Urology at the General Hospital of the People's Liberation Army during the period of November 2012 and October 2018 were reviewed. The retrieval of data was in concordance with institutional IRB regulations. All tumors were histopathologically proven by 18-gauge core needle biopsies under US guidance before the ablation. Renal functions including serum creatinine and urea levels before MWA and 1 day after MWA were retrospectively retrieved from case records.

Imaging examination

Before treatment, all patients were subjected to chest X-ray, abdominal ultrasonography, computed tomography (CT), and/or magnetic resonance imaging (MRI) were performed to evaluate bilateral kidneys and the existence of metastasis.

Microwave ablation ablation protocol

The MWA system (KY-2000; Nanjing Kangyou Medical Treatment Equipment Co., Ltd., Nanjing, China), consisting of MWA generators, flexible coaxial cables, and water-pumping machines, was used to produce the highest power output of 100W at 2450 MHz. The 15-gauge diameter cooled-shaft needle antenna (18 cm length, 11 mm active tip) was applied in this study. Lesions for MWA were decided according to the diagnoses of the tumor on contrast-enhanced imaging pre-MWA. In general, for tumors <2.0 cm in diameter, a single antenna was advanced, whereas two or more antennas were required for tumors with diameters of 2.0 cm or greater.

All patients were kept under intravenous anesthesia and a combination of Propofol (Diprivan; Zeneca Pharmaceuticals, Wilmington, DE) and Ketamine (Shuanghe Pharmaceuticals, Beijing, China) was administered by an anesthesiologist. The antenna was percutaneously advanced into the index tumor under US guidance. MWA output was emitted at a power of 45–60 W for 300 s and prolonged as necessary to attain temperatures sufficient to ensure tumor kill. When the hyperechoic zone covered the entire index tumor on US imaging, the ablation was ceased. Then a needle tract cauterization was routinely performed during the antenna withdrawal to minimize bleeding and tumor seeding along the needle track.


US imaging, contrast-enhanced CT or MRI was routinely employed on day 1-day 3 after the MWA ablation procedure to evaluate the treatment efficacy and technical success. An irregular peripheral enhancement of the ablated lesion indicated a possible residual unablated tumor; consequently, an additional MWA session was repeated within 1 week.

Statistical analysis

The measurement data were presented as the mean ± standard deviation, and compared with Student's t-test or Mann–Whitney test where appropriate. Statistical analysis was performed using SPSS 20.0 software for Windows (SPSS Inc., Chicago, IL, USA). A P < 0.05 was considered statistically significant.

 > Results Top

Patient demographics

In the present study, eight patients (7 males and 1 female; mean age 59.4 ± 9.9 years) who had BRCCs were included for analysis [Table 1]. One patient had received left unilateral nephrectomy 6 months before and one patient had received bilateral nephrectomy 19 months before. These both cases had 1 recurrent tumor in the right kidney, respectively. Two patients had 2 tumors. Three patients had four tumors. The tumor diameters range from 0.7 cm to 6.2 cm. Amongst them, the histological subtype was clear cell carcinoma (19/19).
Table 1: Clinical features of the patients and tumors

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Outcomes of microwave ablation

In total, 20 lesions (11 lesions were in the right kidney, and 9 lesions were in the left kidney) were ablated using 21 US guided percutaneous MWA sessions [Table 1] and [Table 2]. One session was performed to ablate 90% of the RCCs (18/20), and an additional session was repeated for the incompletely destroyed tumors because a residual ablated tumor was detected by US imaging within 3 days after the MWA. All lesions necrosed after MWA ablation [Figure 1] and [Table 2]. Pre-MWA MRI image showing a tumor (white arrow), with a maximal diameter of 58 mm, in the left kidney of a 44-year-old male (left). Post-MWA MRI image showing ablated lesion hypointensity (white arrow) at 1 month (right). Pre-MWA MRI image showing a tumor (white arrow), with a maximal diameter of 40 mm, in the left kidney of a 34-year-old female (left). Post-MWA MRI image showing ablated lesion hypointensity in the ablation zone (white arrow) on day 3 (right). After MWA, there were five patients with mild to moderate fever within 24 h and one patient with severe fever for 9 days. No severe complications occurred during and after the MWA procedure. The median follow-up time was 24 months (ranged from 7 months to 59 months). During the follow-up, there was no local tumor recurrence in 6 of 8 completely ablated tumor lesions. One patient was retreated by MWA 6 months after ablation, and another was retreated by MWA 19 months after ablation due to local tumor recurrence [Figure 2]. Pre-MWA MRI image showing a tumor (white arrow) in the left kidney of a 48-year-old male (left). Post-MWA MRI image showing necrotic lesions (white arrow) on day 3 (right). At 6 months after MWA, MRI image showing a local tumor recurrence with a maximal diameter of 27 mm in the right kidney (left). After MWA retreatment, MRI image showing no residual tumor in the ablation zone (white arrow) on day 3 (right). No patients lost their life after MWA.
Table 2: Tumor location and size

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Figure 1: Pre-MWA and post-MWA treatment MRI images of two patients with RCCs. MRI = Magnetic resonance imaging, MWA = Microwave ablation, RCC = Renal cell carcinomas, white arrow = tumor

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Figure 2: MRI images of a RCC with a maximal diameter of 84 mm, prior to, following and retreated by MWA. MRI = Magnetic resonance imaging, MWA = Percutaneous microwave ablation, RCC = Renal cell carcinomas, white arrow = tumor

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Renal function

After MWA treatment, no obvious changes of renal function were observed in all patients. Compared with the mean levels prior to the MWA, there were no significant differences in the mean serum Cr and BUN levels 1 day after the MWA procedure (6.48 ± 1.93 lmol/L vs. 6.17 ± 0.82 lmol/L, P = 0.683; 107.4 ± 27.90 mmol/L vs. 124.43 ± 39.51 mmol/L, P = 0.335) [Figure 3].
Figure 3: The levels of serum Cr and BUN in 8 patients with bilateral RCCs pre-MWA and post-MWA treatment. Cr = Creatinine, BUN = Blood urea nitrogen

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 > Discussion Top

For the majority of patients with BRCCs, to perform complete resection of the tumors and preserve the normal functional renal parenchyma to avoid dialysis treatment, partial or complete nephrectomy has been considered the first choice of treatment.[12],[13] However, it is challenging to balance between oncological efficacy and preservation of renal function. In addition, certain patients are nonsurgical candidates or refuse surgery due to comorbidities and cosmetic requirements. As nonsurgical treatments, nephron-sparing surgery and image-guided thermal ablation have increasing popularity in recent years due to its safety and efficacy for BRCCs, patients having elder age or with comorbidities.[14],[15],[16],[17],[18] The advantages of them, especially image-guided thermal ablation treatment, have less operative time, decreased operative blood loss, less ischemia time, and fewer complications with equivalent renal functional and oncological outcomes.[19] Furthermore, image-guided thermal ablation treatment has demonstrated good long-term curative effects on local tumor control that are similar to those observed after partial nephrectomy.[4]

Frequently used in thermal ablation methods include cryoablation, RFA, and MWA. Although RFA is used more widely, MWA has several theoretical advantages over RFA in that it requires a shortened ablation time, produces consistently higher intratumor temperatures, can treat larger ablation volumes, is less dependent on the electrical conductivity of tissue, and has smaller limits on energy delivery because of the exponentially increasing electrical impedance of tumor tissue.[20],[21] In terms of the application of MWA in BRCC is limited, this paper present that up to 75% (6/8) of patients treated with MWA have good outcomes upon long-term follow up. Two patients had more than 1-year follow-up with no tumor regrowth after received the second or the third MWA because of the tumor recurrence. One must appreciate that MWA for bilateral RCCs is technically demanding, and thus 75% of patients had good recovery is encouraging.

US-guided MWA has been applied to assist tumor ablation of liver, kidney, and benign prostatic hyperplasia.[16],[17],[18] Cheng also reported 24 cases of RCCs adjacent to the intestinal tract using US-guided MWA treatment.[7] In this series, the use of percutaneous under the guidance of US, complete ablation was successfully achieved in the tumor lesions and no tumor recurrence was detected during the follow-up. The percutaneous US-guided MWA did not affect the residual renal function and pose injury to the adjacent organ.[7] In the present study, seven tumor lesions close to the intestinal tract and 2 lesions close to the liver. US imaging had helped to identify these cases and these tumors were completely ablated without posing injury to the adjacent organ. We analyzed the change of renal function pre-MWA and post-MWA of each patient, no significant elevation was observed. The level of three patients' serum creatinine increased lightly but decreased to the level of pre-MWA in the last follow-up. Hence, clinicians alike should solicit support from US-guided MWA for patients with complex renal tumors or renal dysfunction were attempted, and this would identify anatomy and improve overall surgical outcomes.

Despite the US-guided percutaneous MWA brings approving results to the bilateral RCCs who lost the chance of surgery, one must also reckon the small population size of bilateral RCCs reported in this series, and the follow-up data in our study were limited. The long-term clinical efficiency and safety of MWA for renal tumors of patients with bilateral RCCs and kidney dysfunction required a well-designed prospective study, a larger sample, and dynamic observation of renal function after US-guided MWA.

 > Conclusion Top

Based on these favorable follow-up outcomes, the thermal technique would not harm the residual function and pose unacceptable damage to the adjacent organs. The treatment procedure could be individually tailored, according to the location and size of the tumor. US-guided percutaneous MWA is effective and safe to treat the patients with BRCCs or the patients who lost the chance of surgery can have a positive outcome with correctly selected techniques.


The authors thank the Interventional US, Diagnostic Radiology Department and the Nuclear Medicine Department of the General Hospital of the People's Liberation Army for their assistance.

Compliance with ethical standards

The use of human clinical materials in this study was approved by the Ethical Committee of the General Hospital of the People's Liberation Army. All patients or their caregivers have provided written informed consent.

Financial support and sponsorship

This study was funded by the National Key R and D Program of China (Project No. 2017YFC0112000) and the National Natural Science Foudation of China (Project No. 81622024) to Yu.

Conflicts of interest

There are no conflicts of interest.

 > References Top

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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2]


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