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Percutaneous radiofrequency ablation of renal cell carcinomas in patients with solitary kidney: 6 years experience
European Journal of Radiology 69 (2009) 351–356
Percutaneous radiofrequency ablation of renal cell carcinomas in patients with solitary kidney: 6 years experience Sophia Mylona a , Anna Kokkinaki a , Maria Pomoni b , Panagiota Galani a , Sparti Ntai a , Loukas Thanos c,∗ a
Interventional Radiology - CT Department, HELLENIC RED CROSS Hospital, 1 Athanasaki Str., 11526 Athens, Greece b Interventional Radiology Department, HELLENIC RED CROSS Hospital, 1 Athanasaki Str., 11526 Athens, Greece c Interventional Radiology - CT Department, SOTIRIA hospital, 9 Biskini Str., 15772 Athens, Greece Received 31 July 2007; received in revised form 5 October 2007; accepted 8 October 2007
Abstract Objective: In this study we attempt to present our clinical experience in RFA under CT-guidance, in patients with renal cell carcinoma in a solitary kidney. Material and Method: Between October 2000 and June 2005, 18 patients with solitary kidney and renal cell carcinoma underwent percutaneous CT-guided radiofrequency ablation in our institution. Tumors diameter ranged from 1 to 7 cm and there was no evidence of spread beyond the kidney. The RFA-system used was with expandable needle electrode (7 or 9 arrays). Technical success, recurrence and survival rate and complications were accessed. Patients were available for clinical and laboratory evaluation at a mean follow-up time of 31.2 months (range: 12–72 months). Results: In all cases the electrode was successfully placed at the lesion. The 18 tumors were treated with totally 24 RFA sessions. In small (1–3 cm) exophytic tumors technical success was 85.7%. Residual disease was totally seen in 6/18 tumors which required a 2nd RFA session. The recurrence rate was 11.1% but no recurrence was noticed in tumors less than 3 cm in diameter. No major complications were observed. Serum creatinine values were normal in 17/18 patients till the 3rd-month follow-up. Survival ranged from 12 to 72 months. Conclusion: RFA is an acceptable alternative for patients with small RCCs in a solitary kidney, which are not ideal candidates for surgical resection as their renal function must be preserved. They have an immediate solution to their clinical problem, under a minimally invasive therapy with no serious complications. © 2008 Published by Elsevier Ireland Ltd. Keywords: Radiofrequency ablation; Renal cell carcinoma; Solitary kidney; CT-guidance
1. Introduction Renal cell carcinoma (RCC) is a relatively rare tumor accounting for approximately 3% of malignancies in adults [1]. Widespread dissemination of high-quality imaging has led to increasing detection of small, early stage RCCs in asymptomatic patients [2]. For many years radical nephrectomy has been considered as the treatment of choice for patients with localized RCC and the probability of cure was related to the stage [3–5]. More recent data indicate that in carefully selected patients partial nephrectomy may be an option [1]. It does not remove the entire kidney but only the part containing the carcinoma and it is indicated in
∗
Corresponding author. Tel.: +30 210 6414838; fax: +30 210 6414462. E-mail address: [email protected] (L. Thanos).
0720-048X/$ – see front matter © 2008 Published by Elsevier Ireland Ltd. doi:10.1016/j.ejrad.2007.10.004
small RCCs, (less than 4 cm) in the setting of a normal contralateral kidney [5,6]. Nowadays laparoscopic partial nephrectomy has demonstrated low morbidity and has the advantage of bleeding control and equivalent cancer control to open surgery [7]. Some patients however are not ideal candidates for invasive surgical resection of their renal tumors because of serious comorbidities [2,8,9]. Also the effectiveness of partial nephrectomy (open or laparoscopic) is comparable with the effectiveness of treatment using complete removal of a kidney containing tumor. Advances in imaging and thermal ablation techniques, combined with the above theory, have led to increased interest in image-guided, minimally invasive percutaneous thermal ablative techniques for the treatment of RCC. RFA is one of them. It is a thermal ablative technique that causes tumor destruction by heating. It can be used in open or laparoscopic surgery and percutaneously under computed tomography (CT) or
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ultrasound (U/S) guidance. It has been used mainly on hepatic tumors since the early 1990’s and recently on lung, kidney, adrenal and osseous tumors [10–13]. Substantial evidence indicates that RFA of small RCCs is effective even for complete tumor eradication [4,8,14]. A special group of patients with RCC is that with congenital or acquired solitary kidney. These patients cannot undergo radical nephrectomy without subsequent dialysis or transplantation and partial nephrectomy depends on tumor location and usually leads to diminution of functional nephrons. In such cases there is a need for even less minimally invasive nephron-sparing approaches such as radiofrequency ablation (RFA) [2,15,16]. In this study we present our clinical experience of RFA under CT-guidance, in patients with RCC in a congenital or acquired solitary kidney. We describe the technique, present the complications and evaluate the technical success. Moreover we report our results for a period of 12–72 months after RFA and evaluate the impact of this minimally invasive treatment on renal function and the recurrence and survival rates. 2. Materials and methods 2.1. Patients Between October 2000 and June 2005, we treated 18 patients with solitary kidney and renal cell carcinoma with CT-guided percutaneous radiofrequency ablation (12 male, 6 female; age range 52–84 years; mean age 65 years). Two/eighteen patients had a congenital solitary kidney and 16/18 patients had an acquired solitary kidney owing to previous radical nephrectomy (11/16 were operated because of RCC, 2/16 due to infection, and 3/16 because of serious trauma). Patients who were operated because of RCC presented with contralateral kidney tumor 12–18 months after the initial surgery. The diagnosis of RCC in 13 individuals was based on imaging characteristics (CT or MR imaging). In five atypical cases percutaneous CT-guided core needle biopsy was necessarily performed for the establishment of the diagnosis. Eleven tumors (61.1%) were located in the right kidney and 7 (38.9%) in the left. Eight were exophytic (44.4%), 3 intraparenchymal (16.7%), 5 mixed (27.8%) and 2 central (11.1%). Exophytic are the tumors that arise from the renal cortex, protrude into the perinephric space and are surrounded by fat. Central tumors are located in the medulla and protrude into the hilum and parenchymal tumors are confined to the cortex but do not protrude into the perinephric fat or hilum. Mixed are the tumors that involve both central and peripheral portions of the kidney [16]. Tumors diameter ranged from 1 to 7 cm (average diameter: 3.34 cm). All renal tumors were solid. In all cases there was no radiological or laboratory evidence of tumor spread beyond the kidney (stage I or II). Patients were either high-risk surgical candidates or refused surgery. RFA was proposed to them as an alternative treatment to open partial nephrectomy. Before the ablation the whole procedure and the expected result was explained to the patients in detail and an informed consent was obtained.
Prothrombin time (PT), partial thromboplastin time (PTT), international normalized ratio (INR) and platelet count (PLT count) were assessed before RFA in all cases. Hematocrit, hemoglobin, WBC, blood-urea and serum creatinine were measured and patients received hydration if necessary. All procedures were performed under local anesthesia. For better collaboration analgesic treatment was given 45–60 min before RFA, consisting of 3 mg bromazepam per os and 0.05 g pethidine hydrochloride i.m. Twenty-four RFA sessions were performed totally. 2.2. RFA system The RFA-system used was with expandable needle electrode with 7 or 9 arrays [RITA Medical Systems (Mountain View, CA, USA)]. The selection of the electrode was based on tumor size. 2.3. RFA procedure Patients were placed in prone or lateral decubitous position depending on the site of the lesion. In order to define the exact skin location for the insertion of the device, the area of interest was scanned with 5 mm-thick contiguous slices using spiral CT (Picker 5000, Phillips Medical Systems, the Netherlands). The depth of the lesion was measured at the proper CT image. The electrode was inserted in a stepwise manner. When the electrode was placed at the proper position, the tines were slowly deployed and the device was connected to the RF generator. The power during RFA session ranged between 90 and 110 W, and the temperature from 80 to 110◦ C. The duration of energy emission ranged between 10 and 18 min. In case of patient’s discomfort 2% lidocaine was infused at the skin incision or through the infusion port. In case of large tumors (>4 cm) multiple overlapping ablations were performed for complete tumor necrosis. The attempt was to ablate the whole tumor and a surrounding margin 0.5–1 cm of normal renal parenchyma. At the end of the procedure, an ablation of the track of the needle was performed in order to avoid tumor seeding. To check the immediate response and exclude the possible complications, dual phase, spiral CT was preformed after IV contrast medium administration. All patients were hospitalized for one night for clinical observation. Serum creatinine levels were measured before patients discharge. 2.4. Therapeutic response evaluation Dual phase spiral CT and serum creatinine values were scheduled for follow-up at the 1st- and 3rd-month and every 6 months ever after. Patients were available for evaluation at a mean follow-up of 31.2 months. All of them had at least 1-year followup (range: 12–72 months till September 2006). CT was performed after IV contrast material administration and dual phase scanning protocol (slice thickness: 5 mm, pitch: 1, flow rate: 3.5 ml/s, total volume: 150 ml, scan delay: arterial phase 35 s, venous phase 60 s). The absence of enhancement inside the ablated tumor was considered as total necrosis. Clini-
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cal success was confirmed by the evaluation of serum creatinine and the absence of local recurrence and metastatic disease.
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months later showed multiple liver metastases and died of his disease. Recurrence after successful treatment was seen in 2/18 cases (recurrence rate: 11.1%). The first was a female patient with an exophytic RCC, 4.6 cm in diameter. The patient had local recurrence at the 12-month follow-up, but she refused a 3rd RFA and died 6 months later. The second was a male patient with a mixed in location tumor 6.4 cm in diameter who had local recurrence and metastatic disease at the 12-month follow-up and died because of his disease. In conclusion 5/6 tumors (83.3%) that relapsed after the 1st RFA, were more than 3.9 cm in diameter and 2/2 tumors (100%) that metastasized were more than 6.4 cm at the time of diagnosis. There was no recurrence in tumors less than 3 cm. No major complications were observed. In 2/24 RFA sessions (8.33%), a minor subcapsular hematoma was noticed without hematuria. Three/eighteen patients (16.7%) complained of mild pain at the ablation site, which regressed with analgesics. Survival ranged from 12 to 72 months (mean 31.2 months). Two patients died 17 and 28 months after RFA because of heart attack and car accident. Three/eighteen patients died of their disease. All patients had normal initial serum creatinine values. Immediately after ablation 4/18 patients with tumors >4.6 cm (3 mixed, 1 exophytic) had slightly elevated levels of serum creatinine ranging between 1.3 and 2.0 that became normal till the 3rd-month follow-up (normal values: 0.4–1.1 for females and 1.3 for males). One patient with recurrent disease treated twice with RFA (tumor size 6.4 cm) presented with increased serum creatinine (2.7) at the 12-month follow-up along with spread of the disease to the liver. Two patients with centrally located tumors had normal serum creatinine values.
3. Results In all cases the electrode was successfully placed at the lesion. The 18 RCCs were treated with totally 24 RFA sessions (Table 1). In 7/18 patients (38.9%) tumor diameter ranged from 1 to 3 cm. On the 1st-month CT imaging follow-up after IV contrast administration, 6/7 tumors indicated no sign of enhancement inside them (technical success, 85.7%) (Fig. 1). Two/six were primary malignancies in the patients with congenital solitary kidney. The diameter in 9/18 tumors ranged between 3.1 and 5 cm. Six of these nine tumors showed no enhancement in the area of tumor on the 1st-month follow-up (technical success: 66.7%). Tumor diameter in two individuals was >5 cm (between 5.1 and 7 cm). In both of these cases enhancement was noticed in the area of tumor on the 1st-month follow-up. Technical success was accomplished in 7/8 exophytic tumors (87.5%), 3/3 intraparenchymal tumors (100%), 1/5 mixed tumors (20%) and in 1/2 central tumors (50%). Six/eighteen tumors showed persistent enhancement on the 1st-month follow-up indicating partial necrosis of the tumors (residual disease: 33.3%) and required a 2nd RFA session (Fig. 2). The 2nd RFA session had absolute technical success in 5/6 tumors (83.3%), confirmed at the 1st-month follow-up. In a case of a mixed tumor, 7 cm in diameter, there was persistent enhancement on the 6-month follow-up imaging after the 2nd RFA (incomplete treatment). The patient could not undergo a 3rd RFA due to irreversible coagulopathy and 6
Table 1 Clinical data for 18 patients with RCC in solitary kidney treated with CT guided RF ablation a/a
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Patient data Sex
Age
M M M F F M F M M M F M M F M F F M
55 58 65 53 72 68 80 78 61 69 64 71 84 52 60 72 61 52
Tumor size (cm)
Tumor location
First RFA
1-Month follow-up (tumor necrosis)
Secnd RFA
6-Month follow-up (tumor necrosis)
2.1 1.8 6.4 1.6 3.4 4.0 3.1 7.0 3.2 3.9 3.0 3.4 4.7 4.6 1.0 1.5 3.3 2.1
E IP M IP E E M M E M E E M E C C E IP
+ + + + + + + + + + + + + + + + + +
+ + − + + + + − + − + + − − + − + +
− − + − − − − + − + − − + + − + − −
+ + + + + + + − + + + + + + + + + +
M: male; F: female; E: exophytic; IP: intraparenchymal; M: mixed; C: central; and Rec: recurrence.
12-Month follow-up Tumor necrosis
Meta stases
+ + Rec + + + + − + + + + + Rec + + + +
− − Liver − − − − Liver − − − − − − − − − −
Survival in months
Cause of death
72 30 22 60 54 28 48 16 41 24 32 30 17 18 24 18 15 12
− − The disease − − Car accident − The disease − − − − Heart attack The disease − − − −
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Fig. 1. RFA of a biopsy-proved RCC in a 53-year-old female patient with a solitary kidney. The tumor is 1.6 cm in diameter and is located at the lower pole of the left kidney. (a) Unenhanced CT scan shows a solid intraparenchymal RCC arising from the lower pole of the left kidney. The electrode is placed into the tumor. A small buble gas is present, caused by thermal damage. (b) Contrast-enhanced CT scan (arterial phase) obtained 1-month after RFA shows absence of enhancement, indicating complete tumor necrosis.
Fig. 2. RFA of an RCC in a 65-year-old male patient with a solitary kidney. (a) Unenhanced CT scan shows a solid mixed in location RCC (small protrusion into the upper pole calyces) arising from the upper pole of the left kidney. The electrode is placed into the tumor. (b) Contrast-enhanced CT scan (arterial phase) obtained 1-month after RFA shows enhancement in a small area of tumor indicating incomplete tumor necrosis.
3.1. Statistical analysis Survival analysis was performed using Caplan Meier for all patients and separately for patients with total or partial necrosis at the 1st-month follow-up. The total mean survival time was 31.2 months. Patients with total necrosis had a mean survival time of 38 months while patients with partial necrosis had 20 months. The comparison of the results of these two groups was statistically significant (significance 0.0094). 4. Discussion For many decades radical nephrectomy has been the ‘gold standard’ treatment for patients with RCC. A retrospective study showed that when the tumor is confined within the capsule, the 5year survival rate was 88%. Local recurrence is uncommon, with incidence ranging from 0.8 to 3% [1,17]. In addition approximately 20% of patients undergoing radical nephrectomy develop postoperative complications, and the operative mortality rate is almost 2% [3]. Partial nephrectomy is thought to be equivalent for treating small low-stage RCCs, indicating that renal-sharing procedures can be curative in carefully selected patients [1,4,10]. The incidence of local recurrence following partial nephrectomy the-
oretically should be greater than radical due to the presence of satellite lesions, which are difficult to detect. Some series report it to be 4–13% while others report an incidence similar to radical rephrectomy [17]. Uzzo and Novick found that the rates of major complications ranged from 4 to 30% in nine series [11]. Recently, the increased life expectancy of patients, the increased incidence of small RCCs and the desire to preserve renal parenchyma has propelled minimally invasive techniques such as percutaneous image-guided RFA for the treatment for RCCs [16]. In 2002–2003 seven studies reported totally 195 RFA in renal tumors. The largest study was that of Gervais et al. with 42 RCCs in 34 patients [11,14]. To our knowledge recurrence rates are insufficient and more data will be necessary. Essential 5-year outcome data are still unavailable [15]. Studies have reported treatment outcomes up to a mean of 17 months and the success rate was 88%. Generally the rate of successful RFA treatment in cases of small RCCs, ranges between 79 and 97% or even 100% in some series [8,14]. Gervais et al. reported 100% success rate for the ablation of small (<5 cm), exophytic tumors [11]. Percutaneous, image-guided RFA provides a lot of advantages over surgical resection, including reduced morbidity, outpatient therapy and ability to treat high-risk surgical candidates (such as patients with serious comorbidities, marginal renal
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Fig. 3. RFA of a biopsy-proved RCC in a 55-year-old male patient with solitary kidney. (a) Unenhanced CT scan shows a solid exophytic tumor arising from the right kidney. The patient is in prone position and the electrode is advanced into the tumor. (b) Contrast-enhanced CT scan (arterial phase) obtained 1-month after RFA session shows no detectable enhancement of the tumor. (c) Contrast-enhanced CT scan (arterial phase) of the same patient obtained 1-year after RFA reveals complete necrosis and decrease in tumor’s size.
function, contraindications to general anesthesia and advanced age). RFA minimizes destruction of normal renal tissue and thus minimizes removal of functional nephrons. Patients who can benefit from RFA are those with genetic predisposition to multiple tumors, such as patients with von Hippel–Lindau syndrome, who usually undergo multiple partial nephrectomies for recurring RCCs. On the other hand RFA is a solution for patients with congenital or acquired solitary kidney, who cannot undergo surgical resection because they will result in hemodialysis [8,14,18]. The only absolute contraindications are irreversible coagulopathies and serious medical instability such as sepsis [8,14]. Ablations were performed under CT-guidance because this modality is not depending on patients cooperation (as much as ultrasound) and it can demonstrate even very small tumors, avoiding obscuring artifacts such as bowel gas [8,19]. The final control for residual tumor was assessed by postprocedural imaging (typically CT), at least 1-month after treatment, because immediately after RFA local hyperemia induces enhancement too and may mimic the appearance of viable tumor. Besides RFA energy has prolonged action, provoking late necrosis. Studies have shown that in order to achieve satisfactory results, tumors should not expand beyond Gerota Fascia. When performing RFA in cases of local extension into veins, lymph nodes or distant metastases, cure cannot be accomplished. In cases of invasive or metastatic tumors, RFA is recommended
only for the treatment of hematuria or the reduction of tumor size [4,8]. In our study all RCCs were located in the kidney. It is generally accepted that the success rate of RFA in treating RCCs, depends on tumor’s size and location [9–11]. Substantial and growing evidence indicate that imaging-guided RFA in cases of small RCCs (≤3 cm) is effective for complete tumor necrosis even with a single session (Figs. 3 and 4). The location of the tumor also influences the result of RFA. Even large exophytic tumors are almost always treated successfully. Parenchymal and mainly central RCCs are more difficult to treat [14]. This is because exophytic tumors are surrounded mainly by perirenal fat, which improves the effect of RFA, as it is avascular and provides insulation. Central or mixed tumors are surrounded by vascular renal parenchyma and therefore there is a lot of heat loss [9]. In our study lesions smaller than 3 cm, had 85.7% technical success in the 1st-month follow-up, while lesions bigger than 5 cm had no technical success at the 1st-month follow-up. Totally 6/18 residual cases (33.3%) were seen 1-month after the 1st RFA and 5/6 (83.3%), were larger than 3.9 cm. The residual cases necessitated the application of a second RFA, which had technical success in 5/6 cases (83.3%) at the 1st-month followup. In exophytic tumors technical success was accomplished in 7/8 cases (87.5%), when in mixed tumors it reached only 20%. The total recurrence rate was 11.1%. Tumors ≤3 cm showed no recurrence.
Fig. 4. Contrast-enhanced CT scan of the same male patient with Fig 4. (a) Arterial phase, (b) venous phase obtained 2 years after RFA. Absence of enhancement in the tumor in both arterial and venous phases indicates complete tumor necrosis.
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Another factor that influences the outcome of RFA is the nature of RCC. Carcinomas with high-vascularity distribute heat away from the tumor (heat-sink phenomenon) [19]. In our study in 4/6 cases (66.7%) of residual disease after the 1st ablation, RCCs had high vascularity. It is obvious that in our study tumor size and location were strongly related to the technical success of RFA and vascularity had a good correlation. Tumor size was the major factor, because small tumors treated with RFA, had successful outcome regardless tumor location or vascularity. In a study of 16 RCCs in solitary kidneys the mediam percentage of change in creatinine clearance at a mean follow-up duration of 15.3 months was 9.1% [20]. In our study serum creatinine values were slighted elevated immediately after RFA in 4/18 patients (22.2%) with tumors larger than 4.6 cm in diameter (3 mixed in location, 1 exophytic), that became normal till the 3rd-month follow-up. Only 1/18 patients (5.6%) treated twice with RFA (tumor size 6.4 cm) presented with increased serum creatinine values (2.7) at the 12-month follow-up along with recurrent disease and spread of his disease to the liver. The two patients with centrally located tumors had normal serum creatinine values. So, increased serum creatinine values were seen in large masses and were probably related to the RFA procedure as they came back to normal in a short period of time. Serum creatinine was elevated at the 12-month follow-up only in 1 case of a large, late-stage RCC. Complications after RFA are divided into five categories: haemorrhage, collecting system injury, adjacent organ injury, neuromuscular injury and cutaneous thermal injury [16]. Studies have shown that complications of RFA in the treatment of RCCs are usually clinically insignificant and can be treated on an outpatient basis [8,10]. The rate of serious complications is very low (1% or less) [8,9]. Hematuria is a common complication but it is usually self-limited and resolves within 24 h. Gross hematuria and clinically significant perirenal bleeding is rare [8]. In a study of 159 patients there were only three complications due to the thermal effects of RFA, two cases of ureteral stricture and a thermal injury to the psoas muscle [14]. To our knowledge only two cases of needle track seeding have been reported [8,14]. Some studies report that ablation of RCCs located adjacent to an adrenal gland can induce sudden release of catecholamines [8]. In our study the only complications that occurred in 24 sessions were a minor subcapsular hematoma in two cases (8.33%) that needed no treatment and mild pain at the site of ablation in three patients (12.5%), which regressed with analgesics. There were no procedure-related deaths. 5. Conclusions Percutaneous RFA of renal cell carcinomas in patients with solitary kidney is a rewarding experience. Patients have an immediate solution to their clinical problem, under a minimally invasive therapy with no serious complications. Surgical resection still remains the “gold standard” therapy of small RCCs. However patients with solitary kidney are not ideal candidates
for surgical resection and their renal function must be preserved. In cases like this the use of CT-guided RFA is an acceptable, welltolerated alternative for the management of located renal tumors. The best results are clearly achieved for lesions not larger than 4 cm in diameter. Acknowledgement The authors would like to thank Mr Niko Delikanaki for his assistance with the statistical analysis. References [1] Rizk E-G. Surgical management of renal tumors. Radiol Clin North Am 2003;41(5):1053–65. [2] Ahrar K, Matin S, Wood CG, et al. Percutaneous radiofrequency ablation of renal tumors: technique, complications and outcomes. J Vasc Interv Radiol 2005;16:679–88. [3] Richard AS, Nephrectomy radical, e medicine last updated, August 24, 2005. [4] Ronald JZ. Percutaneous image-guided radiofrequency ablation of renal malignancies. Radiol Clin North Am 2003;41(5):1067–75. [5] Gupta NP, Kumar A, Hemal AK, Dogra PN, Seth A, Kumar R. Open nephron-sparing surgery in renal tumors with normal contralateral kidney: a single centre experience of 8 years. Indian J Urol 2007;23(1):18–22. [6] Gilbert SM, Russo P, Benson MC, Olsson CA, McKiernan JM. The evolving role of partial nephrectomy in the management of renal cell carcinoma. Curr Oncol Rep 2003;5(3):239–44. [7] Benjamin RL. Laparoscopic total and partial nephrectomy. Int Braz J Urol 2002;28:504–9. [8] Zagoria RJ. Imaging-guided radiofrequency ablation of renal masses. Radiographics 2004;24:59–71. [9] Chiou YY, Hwang JI, Chou YH, Wang JH, Chiang JH, Chang CY. Percutaneous radiofrequency ablation of renal cell carcinoma. J Chin Med Assoc 2005;68(5):221–5. [10] Zagoria RJ, Hawkins AD, Clark PE, Hall MC, Matlaga BR, Dyer RB, Chen MY. Percutaneous CT-guided radiofrequency ablation of renal neoplasms: factors influencing success. AJR 2004;183:201–7. [11] Gervais DA, McGovern FJ, Arellano RS, McDougal WS, Mueller PR. Renal cell carcinoma: clinical experience and technical success with radiofrequency ablation of 42 tumors. Radiology 2003;226:417–24. [12] Thanos L, Mylona S, Pomoni M, Kalioras V, Zoganas L, Batakis N. Primary lung cancer: treatment with radio-frequency thermal ablation. Eur Radiol 2004;14:897–901. ˝ [13] Geyik S, Akhan O, Abbaso˘glu O, Akıncı D, Ozkan OS¸, Hamalo˘glu E, ˝ Ozmen M. Radiofrequency ablation of unresectable hepatic tumors. TSR Diagn Interv Radiol 2006;12(4):195–200. [14] Andrew H-P, Nahum Goldberg S. Review of radiofrequency ablation for renal cell carcinoma. Am Assoc Cancer Res 2004;10:6328s–34s. [15] Veltri A, De Fazio G, Malfitana V, Isolato G, Fontana D, Tizzani A, Gandini G. Percutaneous US-guided RF thermal ablation for malignant renal tumors: preliminary results in 13 patients. Eur Radiol 2004;14(12):2303–10. [16] Mc Dougal WS. Radiofrequency ablation of renal cell carcinoma. BJU Int 2007;99:1271–2. [17] Janzen KN, Kim HL, Figlin RA, Belldegrun AS. Surveillance after radical or partial nephrectomy for localized renal cell carcinoma and management of recurrent disease. Urol Clin North Am 2003;30(4):843–52. [18] Memarsadeghi M, Schmook T, Remzi M, Weber M, Potscher G, Lammer J, Kettenbach J. Percutaneous radiofrequency ablation of renal tumors: midterm results in 16 patients. Eur J Radiol 2006;59(2):183–9. [19] Goldberg SN, Gazelle GS, Mueller PR. Thermal ablation therapy for focal malignancy. AJR 2000;174:323–31. [20] Jacobsohn KM, Ahrar K, Wood CG, Matin SF. Is radiofrequency ablation safe for solitary kidneys? Urology 2007;69(5):819–23.
Percutaneous radiofrequency ablation of renal cell carcinomas in patients with solitary kidney: 6 years experience Sophia Mylona a , Anna Kokkinaki a , Maria Pomoni b , Panagiota Galani a , Sparti Ntai a , Loukas Thanos c,∗ a
Interventional Radiology - CT Department, HELLENIC RED CROSS Hospital, 1 Athanasaki Str., 11526 Athens, Greece b Interventional Radiology Department, HELLENIC RED CROSS Hospital, 1 Athanasaki Str., 11526 Athens, Greece c Interventional Radiology - CT Department, SOTIRIA hospital, 9 Biskini Str., 15772 Athens, Greece Received 31 July 2007; received in revised form 5 October 2007; accepted 8 October 2007
Abstract Objective: In this study we attempt to present our clinical experience in RFA under CT-guidance, in patients with renal cell carcinoma in a solitary kidney. Material and Method: Between October 2000 and June 2005, 18 patients with solitary kidney and renal cell carcinoma underwent percutaneous CT-guided radiofrequency ablation in our institution. Tumors diameter ranged from 1 to 7 cm and there was no evidence of spread beyond the kidney. The RFA-system used was with expandable needle electrode (7 or 9 arrays). Technical success, recurrence and survival rate and complications were accessed. Patients were available for clinical and laboratory evaluation at a mean follow-up time of 31.2 months (range: 12–72 months). Results: In all cases the electrode was successfully placed at the lesion. The 18 tumors were treated with totally 24 RFA sessions. In small (1–3 cm) exophytic tumors technical success was 85.7%. Residual disease was totally seen in 6/18 tumors which required a 2nd RFA session. The recurrence rate was 11.1% but no recurrence was noticed in tumors less than 3 cm in diameter. No major complications were observed. Serum creatinine values were normal in 17/18 patients till the 3rd-month follow-up. Survival ranged from 12 to 72 months. Conclusion: RFA is an acceptable alternative for patients with small RCCs in a solitary kidney, which are not ideal candidates for surgical resection as their renal function must be preserved. They have an immediate solution to their clinical problem, under a minimally invasive therapy with no serious complications. © 2008 Published by Elsevier Ireland Ltd. Keywords: Radiofrequency ablation; Renal cell carcinoma; Solitary kidney; CT-guidance
1. Introduction Renal cell carcinoma (RCC) is a relatively rare tumor accounting for approximately 3% of malignancies in adults [1]. Widespread dissemination of high-quality imaging has led to increasing detection of small, early stage RCCs in asymptomatic patients [2]. For many years radical nephrectomy has been considered as the treatment of choice for patients with localized RCC and the probability of cure was related to the stage [3–5]. More recent data indicate that in carefully selected patients partial nephrectomy may be an option [1]. It does not remove the entire kidney but only the part containing the carcinoma and it is indicated in
∗
Corresponding author. Tel.: +30 210 6414838; fax: +30 210 6414462. E-mail address: [email protected] (L. Thanos).
0720-048X/$ – see front matter © 2008 Published by Elsevier Ireland Ltd. doi:10.1016/j.ejrad.2007.10.004
small RCCs, (less than 4 cm) in the setting of a normal contralateral kidney [5,6]. Nowadays laparoscopic partial nephrectomy has demonstrated low morbidity and has the advantage of bleeding control and equivalent cancer control to open surgery [7]. Some patients however are not ideal candidates for invasive surgical resection of their renal tumors because of serious comorbidities [2,8,9]. Also the effectiveness of partial nephrectomy (open or laparoscopic) is comparable with the effectiveness of treatment using complete removal of a kidney containing tumor. Advances in imaging and thermal ablation techniques, combined with the above theory, have led to increased interest in image-guided, minimally invasive percutaneous thermal ablative techniques for the treatment of RCC. RFA is one of them. It is a thermal ablative technique that causes tumor destruction by heating. It can be used in open or laparoscopic surgery and percutaneously under computed tomography (CT) or
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ultrasound (U/S) guidance. It has been used mainly on hepatic tumors since the early 1990’s and recently on lung, kidney, adrenal and osseous tumors [10–13]. Substantial evidence indicates that RFA of small RCCs is effective even for complete tumor eradication [4,8,14]. A special group of patients with RCC is that with congenital or acquired solitary kidney. These patients cannot undergo radical nephrectomy without subsequent dialysis or transplantation and partial nephrectomy depends on tumor location and usually leads to diminution of functional nephrons. In such cases there is a need for even less minimally invasive nephron-sparing approaches such as radiofrequency ablation (RFA) [2,15,16]. In this study we present our clinical experience of RFA under CT-guidance, in patients with RCC in a congenital or acquired solitary kidney. We describe the technique, present the complications and evaluate the technical success. Moreover we report our results for a period of 12–72 months after RFA and evaluate the impact of this minimally invasive treatment on renal function and the recurrence and survival rates. 2. Materials and methods 2.1. Patients Between October 2000 and June 2005, we treated 18 patients with solitary kidney and renal cell carcinoma with CT-guided percutaneous radiofrequency ablation (12 male, 6 female; age range 52–84 years; mean age 65 years). Two/eighteen patients had a congenital solitary kidney and 16/18 patients had an acquired solitary kidney owing to previous radical nephrectomy (11/16 were operated because of RCC, 2/16 due to infection, and 3/16 because of serious trauma). Patients who were operated because of RCC presented with contralateral kidney tumor 12–18 months after the initial surgery. The diagnosis of RCC in 13 individuals was based on imaging characteristics (CT or MR imaging). In five atypical cases percutaneous CT-guided core needle biopsy was necessarily performed for the establishment of the diagnosis. Eleven tumors (61.1%) were located in the right kidney and 7 (38.9%) in the left. Eight were exophytic (44.4%), 3 intraparenchymal (16.7%), 5 mixed (27.8%) and 2 central (11.1%). Exophytic are the tumors that arise from the renal cortex, protrude into the perinephric space and are surrounded by fat. Central tumors are located in the medulla and protrude into the hilum and parenchymal tumors are confined to the cortex but do not protrude into the perinephric fat or hilum. Mixed are the tumors that involve both central and peripheral portions of the kidney [16]. Tumors diameter ranged from 1 to 7 cm (average diameter: 3.34 cm). All renal tumors were solid. In all cases there was no radiological or laboratory evidence of tumor spread beyond the kidney (stage I or II). Patients were either high-risk surgical candidates or refused surgery. RFA was proposed to them as an alternative treatment to open partial nephrectomy. Before the ablation the whole procedure and the expected result was explained to the patients in detail and an informed consent was obtained.
Prothrombin time (PT), partial thromboplastin time (PTT), international normalized ratio (INR) and platelet count (PLT count) were assessed before RFA in all cases. Hematocrit, hemoglobin, WBC, blood-urea and serum creatinine were measured and patients received hydration if necessary. All procedures were performed under local anesthesia. For better collaboration analgesic treatment was given 45–60 min before RFA, consisting of 3 mg bromazepam per os and 0.05 g pethidine hydrochloride i.m. Twenty-four RFA sessions were performed totally. 2.2. RFA system The RFA-system used was with expandable needle electrode with 7 or 9 arrays [RITA Medical Systems (Mountain View, CA, USA)]. The selection of the electrode was based on tumor size. 2.3. RFA procedure Patients were placed in prone or lateral decubitous position depending on the site of the lesion. In order to define the exact skin location for the insertion of the device, the area of interest was scanned with 5 mm-thick contiguous slices using spiral CT (Picker 5000, Phillips Medical Systems, the Netherlands). The depth of the lesion was measured at the proper CT image. The electrode was inserted in a stepwise manner. When the electrode was placed at the proper position, the tines were slowly deployed and the device was connected to the RF generator. The power during RFA session ranged between 90 and 110 W, and the temperature from 80 to 110◦ C. The duration of energy emission ranged between 10 and 18 min. In case of patient’s discomfort 2% lidocaine was infused at the skin incision or through the infusion port. In case of large tumors (>4 cm) multiple overlapping ablations were performed for complete tumor necrosis. The attempt was to ablate the whole tumor and a surrounding margin 0.5–1 cm of normal renal parenchyma. At the end of the procedure, an ablation of the track of the needle was performed in order to avoid tumor seeding. To check the immediate response and exclude the possible complications, dual phase, spiral CT was preformed after IV contrast medium administration. All patients were hospitalized for one night for clinical observation. Serum creatinine levels were measured before patients discharge. 2.4. Therapeutic response evaluation Dual phase spiral CT and serum creatinine values were scheduled for follow-up at the 1st- and 3rd-month and every 6 months ever after. Patients were available for evaluation at a mean follow-up of 31.2 months. All of them had at least 1-year followup (range: 12–72 months till September 2006). CT was performed after IV contrast material administration and dual phase scanning protocol (slice thickness: 5 mm, pitch: 1, flow rate: 3.5 ml/s, total volume: 150 ml, scan delay: arterial phase 35 s, venous phase 60 s). The absence of enhancement inside the ablated tumor was considered as total necrosis. Clini-
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cal success was confirmed by the evaluation of serum creatinine and the absence of local recurrence and metastatic disease.
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months later showed multiple liver metastases and died of his disease. Recurrence after successful treatment was seen in 2/18 cases (recurrence rate: 11.1%). The first was a female patient with an exophytic RCC, 4.6 cm in diameter. The patient had local recurrence at the 12-month follow-up, but she refused a 3rd RFA and died 6 months later. The second was a male patient with a mixed in location tumor 6.4 cm in diameter who had local recurrence and metastatic disease at the 12-month follow-up and died because of his disease. In conclusion 5/6 tumors (83.3%) that relapsed after the 1st RFA, were more than 3.9 cm in diameter and 2/2 tumors (100%) that metastasized were more than 6.4 cm at the time of diagnosis. There was no recurrence in tumors less than 3 cm. No major complications were observed. In 2/24 RFA sessions (8.33%), a minor subcapsular hematoma was noticed without hematuria. Three/eighteen patients (16.7%) complained of mild pain at the ablation site, which regressed with analgesics. Survival ranged from 12 to 72 months (mean 31.2 months). Two patients died 17 and 28 months after RFA because of heart attack and car accident. Three/eighteen patients died of their disease. All patients had normal initial serum creatinine values. Immediately after ablation 4/18 patients with tumors >4.6 cm (3 mixed, 1 exophytic) had slightly elevated levels of serum creatinine ranging between 1.3 and 2.0 that became normal till the 3rd-month follow-up (normal values: 0.4–1.1 for females and 1.3 for males). One patient with recurrent disease treated twice with RFA (tumor size 6.4 cm) presented with increased serum creatinine (2.7) at the 12-month follow-up along with spread of the disease to the liver. Two patients with centrally located tumors had normal serum creatinine values.
3. Results In all cases the electrode was successfully placed at the lesion. The 18 RCCs were treated with totally 24 RFA sessions (Table 1). In 7/18 patients (38.9%) tumor diameter ranged from 1 to 3 cm. On the 1st-month CT imaging follow-up after IV contrast administration, 6/7 tumors indicated no sign of enhancement inside them (technical success, 85.7%) (Fig. 1). Two/six were primary malignancies in the patients with congenital solitary kidney. The diameter in 9/18 tumors ranged between 3.1 and 5 cm. Six of these nine tumors showed no enhancement in the area of tumor on the 1st-month follow-up (technical success: 66.7%). Tumor diameter in two individuals was >5 cm (between 5.1 and 7 cm). In both of these cases enhancement was noticed in the area of tumor on the 1st-month follow-up. Technical success was accomplished in 7/8 exophytic tumors (87.5%), 3/3 intraparenchymal tumors (100%), 1/5 mixed tumors (20%) and in 1/2 central tumors (50%). Six/eighteen tumors showed persistent enhancement on the 1st-month follow-up indicating partial necrosis of the tumors (residual disease: 33.3%) and required a 2nd RFA session (Fig. 2). The 2nd RFA session had absolute technical success in 5/6 tumors (83.3%), confirmed at the 1st-month follow-up. In a case of a mixed tumor, 7 cm in diameter, there was persistent enhancement on the 6-month follow-up imaging after the 2nd RFA (incomplete treatment). The patient could not undergo a 3rd RFA due to irreversible coagulopathy and 6
Table 1 Clinical data for 18 patients with RCC in solitary kidney treated with CT guided RF ablation a/a
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Patient data Sex
Age
M M M F F M F M M M F M M F M F F M
55 58 65 53 72 68 80 78 61 69 64 71 84 52 60 72 61 52
Tumor size (cm)
Tumor location
First RFA
1-Month follow-up (tumor necrosis)
Secnd RFA
6-Month follow-up (tumor necrosis)
2.1 1.8 6.4 1.6 3.4 4.0 3.1 7.0 3.2 3.9 3.0 3.4 4.7 4.6 1.0 1.5 3.3 2.1
E IP M IP E E M M E M E E M E C C E IP
+ + + + + + + + + + + + + + + + + +
+ + − + + + + − + − + + − − + − + +
− − + − − − − + − + − − + + − + − −
+ + + + + + + − + + + + + + + + + +
M: male; F: female; E: exophytic; IP: intraparenchymal; M: mixed; C: central; and Rec: recurrence.
12-Month follow-up Tumor necrosis
Meta stases
+ + Rec + + + + − + + + + + Rec + + + +
− − Liver − − − − Liver − − − − − − − − − −
Survival in months
Cause of death
72 30 22 60 54 28 48 16 41 24 32 30 17 18 24 18 15 12
− − The disease − − Car accident − The disease − − − − Heart attack The disease − − − −
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Fig. 1. RFA of a biopsy-proved RCC in a 53-year-old female patient with a solitary kidney. The tumor is 1.6 cm in diameter and is located at the lower pole of the left kidney. (a) Unenhanced CT scan shows a solid intraparenchymal RCC arising from the lower pole of the left kidney. The electrode is placed into the tumor. A small buble gas is present, caused by thermal damage. (b) Contrast-enhanced CT scan (arterial phase) obtained 1-month after RFA shows absence of enhancement, indicating complete tumor necrosis.
Fig. 2. RFA of an RCC in a 65-year-old male patient with a solitary kidney. (a) Unenhanced CT scan shows a solid mixed in location RCC (small protrusion into the upper pole calyces) arising from the upper pole of the left kidney. The electrode is placed into the tumor. (b) Contrast-enhanced CT scan (arterial phase) obtained 1-month after RFA shows enhancement in a small area of tumor indicating incomplete tumor necrosis.
3.1. Statistical analysis Survival analysis was performed using Caplan Meier for all patients and separately for patients with total or partial necrosis at the 1st-month follow-up. The total mean survival time was 31.2 months. Patients with total necrosis had a mean survival time of 38 months while patients with partial necrosis had 20 months. The comparison of the results of these two groups was statistically significant (significance 0.0094). 4. Discussion For many decades radical nephrectomy has been the ‘gold standard’ treatment for patients with RCC. A retrospective study showed that when the tumor is confined within the capsule, the 5year survival rate was 88%. Local recurrence is uncommon, with incidence ranging from 0.8 to 3% [1,17]. In addition approximately 20% of patients undergoing radical nephrectomy develop postoperative complications, and the operative mortality rate is almost 2% [3]. Partial nephrectomy is thought to be equivalent for treating small low-stage RCCs, indicating that renal-sharing procedures can be curative in carefully selected patients [1,4,10]. The incidence of local recurrence following partial nephrectomy the-
oretically should be greater than radical due to the presence of satellite lesions, which are difficult to detect. Some series report it to be 4–13% while others report an incidence similar to radical rephrectomy [17]. Uzzo and Novick found that the rates of major complications ranged from 4 to 30% in nine series [11]. Recently, the increased life expectancy of patients, the increased incidence of small RCCs and the desire to preserve renal parenchyma has propelled minimally invasive techniques such as percutaneous image-guided RFA for the treatment for RCCs [16]. In 2002–2003 seven studies reported totally 195 RFA in renal tumors. The largest study was that of Gervais et al. with 42 RCCs in 34 patients [11,14]. To our knowledge recurrence rates are insufficient and more data will be necessary. Essential 5-year outcome data are still unavailable [15]. Studies have reported treatment outcomes up to a mean of 17 months and the success rate was 88%. Generally the rate of successful RFA treatment in cases of small RCCs, ranges between 79 and 97% or even 100% in some series [8,14]. Gervais et al. reported 100% success rate for the ablation of small (<5 cm), exophytic tumors [11]. Percutaneous, image-guided RFA provides a lot of advantages over surgical resection, including reduced morbidity, outpatient therapy and ability to treat high-risk surgical candidates (such as patients with serious comorbidities, marginal renal
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Fig. 3. RFA of a biopsy-proved RCC in a 55-year-old male patient with solitary kidney. (a) Unenhanced CT scan shows a solid exophytic tumor arising from the right kidney. The patient is in prone position and the electrode is advanced into the tumor. (b) Contrast-enhanced CT scan (arterial phase) obtained 1-month after RFA session shows no detectable enhancement of the tumor. (c) Contrast-enhanced CT scan (arterial phase) of the same patient obtained 1-year after RFA reveals complete necrosis and decrease in tumor’s size.
function, contraindications to general anesthesia and advanced age). RFA minimizes destruction of normal renal tissue and thus minimizes removal of functional nephrons. Patients who can benefit from RFA are those with genetic predisposition to multiple tumors, such as patients with von Hippel–Lindau syndrome, who usually undergo multiple partial nephrectomies for recurring RCCs. On the other hand RFA is a solution for patients with congenital or acquired solitary kidney, who cannot undergo surgical resection because they will result in hemodialysis [8,14,18]. The only absolute contraindications are irreversible coagulopathies and serious medical instability such as sepsis [8,14]. Ablations were performed under CT-guidance because this modality is not depending on patients cooperation (as much as ultrasound) and it can demonstrate even very small tumors, avoiding obscuring artifacts such as bowel gas [8,19]. The final control for residual tumor was assessed by postprocedural imaging (typically CT), at least 1-month after treatment, because immediately after RFA local hyperemia induces enhancement too and may mimic the appearance of viable tumor. Besides RFA energy has prolonged action, provoking late necrosis. Studies have shown that in order to achieve satisfactory results, tumors should not expand beyond Gerota Fascia. When performing RFA in cases of local extension into veins, lymph nodes or distant metastases, cure cannot be accomplished. In cases of invasive or metastatic tumors, RFA is recommended
only for the treatment of hematuria or the reduction of tumor size [4,8]. In our study all RCCs were located in the kidney. It is generally accepted that the success rate of RFA in treating RCCs, depends on tumor’s size and location [9–11]. Substantial and growing evidence indicate that imaging-guided RFA in cases of small RCCs (≤3 cm) is effective for complete tumor necrosis even with a single session (Figs. 3 and 4). The location of the tumor also influences the result of RFA. Even large exophytic tumors are almost always treated successfully. Parenchymal and mainly central RCCs are more difficult to treat [14]. This is because exophytic tumors are surrounded mainly by perirenal fat, which improves the effect of RFA, as it is avascular and provides insulation. Central or mixed tumors are surrounded by vascular renal parenchyma and therefore there is a lot of heat loss [9]. In our study lesions smaller than 3 cm, had 85.7% technical success in the 1st-month follow-up, while lesions bigger than 5 cm had no technical success at the 1st-month follow-up. Totally 6/18 residual cases (33.3%) were seen 1-month after the 1st RFA and 5/6 (83.3%), were larger than 3.9 cm. The residual cases necessitated the application of a second RFA, which had technical success in 5/6 cases (83.3%) at the 1st-month followup. In exophytic tumors technical success was accomplished in 7/8 cases (87.5%), when in mixed tumors it reached only 20%. The total recurrence rate was 11.1%. Tumors ≤3 cm showed no recurrence.
Fig. 4. Contrast-enhanced CT scan of the same male patient with Fig 4. (a) Arterial phase, (b) venous phase obtained 2 years after RFA. Absence of enhancement in the tumor in both arterial and venous phases indicates complete tumor necrosis.
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Another factor that influences the outcome of RFA is the nature of RCC. Carcinomas with high-vascularity distribute heat away from the tumor (heat-sink phenomenon) [19]. In our study in 4/6 cases (66.7%) of residual disease after the 1st ablation, RCCs had high vascularity. It is obvious that in our study tumor size and location were strongly related to the technical success of RFA and vascularity had a good correlation. Tumor size was the major factor, because small tumors treated with RFA, had successful outcome regardless tumor location or vascularity. In a study of 16 RCCs in solitary kidneys the mediam percentage of change in creatinine clearance at a mean follow-up duration of 15.3 months was 9.1% [20]. In our study serum creatinine values were slighted elevated immediately after RFA in 4/18 patients (22.2%) with tumors larger than 4.6 cm in diameter (3 mixed in location, 1 exophytic), that became normal till the 3rd-month follow-up. Only 1/18 patients (5.6%) treated twice with RFA (tumor size 6.4 cm) presented with increased serum creatinine values (2.7) at the 12-month follow-up along with recurrent disease and spread of his disease to the liver. The two patients with centrally located tumors had normal serum creatinine values. So, increased serum creatinine values were seen in large masses and were probably related to the RFA procedure as they came back to normal in a short period of time. Serum creatinine was elevated at the 12-month follow-up only in 1 case of a large, late-stage RCC. Complications after RFA are divided into five categories: haemorrhage, collecting system injury, adjacent organ injury, neuromuscular injury and cutaneous thermal injury [16]. Studies have shown that complications of RFA in the treatment of RCCs are usually clinically insignificant and can be treated on an outpatient basis [8,10]. The rate of serious complications is very low (1% or less) [8,9]. Hematuria is a common complication but it is usually self-limited and resolves within 24 h. Gross hematuria and clinically significant perirenal bleeding is rare [8]. In a study of 159 patients there were only three complications due to the thermal effects of RFA, two cases of ureteral stricture and a thermal injury to the psoas muscle [14]. To our knowledge only two cases of needle track seeding have been reported [8,14]. Some studies report that ablation of RCCs located adjacent to an adrenal gland can induce sudden release of catecholamines [8]. In our study the only complications that occurred in 24 sessions were a minor subcapsular hematoma in two cases (8.33%) that needed no treatment and mild pain at the site of ablation in three patients (12.5%), which regressed with analgesics. There were no procedure-related deaths. 5. Conclusions Percutaneous RFA of renal cell carcinomas in patients with solitary kidney is a rewarding experience. Patients have an immediate solution to their clinical problem, under a minimally invasive therapy with no serious complications. Surgical resection still remains the “gold standard” therapy of small RCCs. However patients with solitary kidney are not ideal candidates
for surgical resection and their renal function must be preserved. In cases like this the use of CT-guided RFA is an acceptable, welltolerated alternative for the management of located renal tumors. The best results are clearly achieved for lesions not larger than 4 cm in diameter. Acknowledgement The authors would like to thank Mr Niko Delikanaki for his assistance with the statistical analysis. References [1] Rizk E-G. Surgical management of renal tumors. Radiol Clin North Am 2003;41(5):1053–65. [2] Ahrar K, Matin S, Wood CG, et al. Percutaneous radiofrequency ablation of renal tumors: technique, complications and outcomes. J Vasc Interv Radiol 2005;16:679–88. [3] Richard AS, Nephrectomy radical, e medicine last updated, August 24, 2005. [4] Ronald JZ. Percutaneous image-guided radiofrequency ablation of renal malignancies. Radiol Clin North Am 2003;41(5):1067–75. [5] Gupta NP, Kumar A, Hemal AK, Dogra PN, Seth A, Kumar R. Open nephron-sparing surgery in renal tumors with normal contralateral kidney: a single centre experience of 8 years. Indian J Urol 2007;23(1):18–22. [6] Gilbert SM, Russo P, Benson MC, Olsson CA, McKiernan JM. The evolving role of partial nephrectomy in the management of renal cell carcinoma. Curr Oncol Rep 2003;5(3):239–44. [7] Benjamin RL. Laparoscopic total and partial nephrectomy. Int Braz J Urol 2002;28:504–9. [8] Zagoria RJ. Imaging-guided radiofrequency ablation of renal masses. Radiographics 2004;24:59–71. [9] Chiou YY, Hwang JI, Chou YH, Wang JH, Chiang JH, Chang CY. Percutaneous radiofrequency ablation of renal cell carcinoma. J Chin Med Assoc 2005;68(5):221–5. [10] Zagoria RJ, Hawkins AD, Clark PE, Hall MC, Matlaga BR, Dyer RB, Chen MY. Percutaneous CT-guided radiofrequency ablation of renal neoplasms: factors influencing success. AJR 2004;183:201–7. [11] Gervais DA, McGovern FJ, Arellano RS, McDougal WS, Mueller PR. Renal cell carcinoma: clinical experience and technical success with radiofrequency ablation of 42 tumors. Radiology 2003;226:417–24. [12] Thanos L, Mylona S, Pomoni M, Kalioras V, Zoganas L, Batakis N. Primary lung cancer: treatment with radio-frequency thermal ablation. Eur Radiol 2004;14:897–901. ˝ [13] Geyik S, Akhan O, Abbaso˘glu O, Akıncı D, Ozkan OS¸, Hamalo˘glu E, ˝ Ozmen M. Radiofrequency ablation of unresectable hepatic tumors. TSR Diagn Interv Radiol 2006;12(4):195–200. [14] Andrew H-P, Nahum Goldberg S. Review of radiofrequency ablation for renal cell carcinoma. Am Assoc Cancer Res 2004;10:6328s–34s. [15] Veltri A, De Fazio G, Malfitana V, Isolato G, Fontana D, Tizzani A, Gandini G. Percutaneous US-guided RF thermal ablation for malignant renal tumors: preliminary results in 13 patients. Eur Radiol 2004;14(12):2303–10. [16] Mc Dougal WS. Radiofrequency ablation of renal cell carcinoma. BJU Int 2007;99:1271–2. [17] Janzen KN, Kim HL, Figlin RA, Belldegrun AS. Surveillance after radical or partial nephrectomy for localized renal cell carcinoma and management of recurrent disease. Urol Clin North Am 2003;30(4):843–52. [18] Memarsadeghi M, Schmook T, Remzi M, Weber M, Potscher G, Lammer J, Kettenbach J. Percutaneous radiofrequency ablation of renal tumors: midterm results in 16 patients. Eur J Radiol 2006;59(2):183–9. [19] Goldberg SN, Gazelle GS, Mueller PR. Thermal ablation therapy for focal malignancy. AJR 2000;174:323–31. [20] Jacobsohn KM, Ahrar K, Wood CG, Matin SF. Is radiofrequency ablation safe for solitary kidneys? Urology 2007;69(5):819–23.