Imaging-guided radiofrequency ablation of solid renal tumors

Radiofrequency Ablation Combined with Radioactive Seed Implantation for Nonsmall Cell Lung Cancer

The aim of this study is to investigate the value of radiofrequency ablation combined with radioactive seed implantation in nonsmall cell lung cancer treatment. 30 patients with primary nonsmall cell lung cancer were randomly divided into two groups. Group A was treated with radiofrequency ablation combined with radiation seed implantation, and group B was treated with radiofrequency ablation only. We compared the incidence of complications in the two groups and reviewed the effective percentage every 3 months. All patients were treated successfully, and there were no deaths during treatment. There were no deaths and no cases of distant organ metastasis in nine months of follow-up. There were no significant differences in treatment-related complications between the two groups. The early postoperative (three and six months) effective percentage was not significantly different (P > 0.05). After 9 months, the postoperative effective rate for group A (9/15) was significantly different from that for group B (radiofrequency ablation) (6/15) (P < 0.05). Radiofrequency ablation combined with radiation 125I seed implantation can complement each other in the treatment of nonsmall cell lung cancer.

Percutaneous ablation or minimally invasive partial nephrectomy for cT1a renal masses? A propensity score-matched analysis

OBJECTIVE

Local tumor ablation to treat small renal mass is increasing. The aim of the present study was to compare oncologic outcomes among patients with T1 renal mass treated with partial nephrectomy and local tumor ablation.

METHODS

To reduce the inherent differences between patients undergoing laparoscopic or robot-assisted partial nephrectomy (n = 405) and local tumor ablation (n = 137), we used a 1:1 propensity score-matched analysis. Local tumor ablation consisted of radiofrequency ablation and cryoablation. Disease-free survival, overall survival and other causes mortality-free survival rates were estimated using the Kaplan-Meier method. Multivariable logistic regression and competing-risk regression models were used to identify predictors of complications, recurrence and other causes mortality, respectively.

RESULTS

Partial nephrectomy had higher disease-free survival estimates, as compared with local tumor ablation (92.8% vs 80.4% at 5 years, P = 0.02), with no significant difference between radiofrequency ablation and cryoablation (P = 0.9). Ablation showed comparable overall survival estimates to partial nephrectomy (91% vs 95.8% at 5 years, P = 0.6). The 5-year recurrence rates were 7.9% versus 23.8% for patients aged ≤70 years, and 2.5% versus 11.9% for patients aged >70 years treated with partial nephrectomy and ablation, respectively; the 5-year other causes mortality rates were 0% and 2.2% for patients treated with partial nephrectomy and ablation aged ≤70 years, and 3% versus 10.9% for patients aged >70 years treated with partial nephrectomy and ablation, respectively. At multivariable analysis, ablation was associated with fewer complications (odds ratio 0.41; P = 0.01). At competing risks analysis, age (hazard ratio 0.96) and ablation (hazard ratio 4.56) were independent predictors of disease recurrence (all P ≤ 0.008).

CONCLUSIONS

Local tumor ablation showed a higher risk of recurrence and lower risk of complications compared with partial nephrectomy, with comparable overall survival rates.

Radiofrequency Ablation of Small Renal Masses

Although the incidence of localized renal cell carcinoma has increased in recent decades due to greater use of imaging, the treatment has shifted to less invasive, nephron-sparing approaches. Radiofrequency ablation (RFA) is one accepted treatment modality for patients with small renal masses, and it has the advantage of being minimally invasive and highly nephron sparing, with the additional benefits of reduced blood loss and complication rates. We describe our experience with RFA with an accompanying instructional video outlining the procedure's key components.

Percutaneous tumor ablation versus partial nephrectomy for small renal mass: the impact of histologic variant and tumor size

BACKGROUND

The aim, of this study was to investigate recurrence rates in patients with T1 renal cell carcinoma (RCC) undergone partial nephrectomy (PN), radiofrequency ablation (RFA) or cryoablation (Cryo).

METHODS

We retrospectively evaluated data from 665 (81.4%), 68 (8.3%) and 83 (10.3%) patients who underwent PN, RFA and Cryo, respectively. Kaplan-Meier curves depict recurrence-free survival (RFS) rates in the overall population and after stratifying according to tumor's histology (namely, clear cell RCC and non-clear RCC) and size (namely <2 cm and 2-4 cm). Multivariable Cox regression model was used to identify predictors of recurrence. Cumulative-incidence plots evaluated disease recurrence and other causes of mortality (OCM).

RESULTS

Patients referred to PN experienced higher RFS rate compared to those treated with RFA and Cryo at 60-month in the overall population (96.4% vs. 79.4% vs. 87.8%), in patients with clear cell RCC (93.3% vs. 75% vs. 80.4%) and in those with tumor of 2-4 cm (97.3% vs. 78% and 84.4%; all P≤0.01). In patients with non-clear cell RCC and with tumor <2cm, PN showed higher RFS rate at 60-month as compared to RFA (97.9% vs. 84.4% and 95.1% vs. 78.1%, respectively: all P≤0.02). At multi-variate analysis, ablative techniques (RFA [HR=4.03] and Cryo [HR=3.86]) were independent predictors of recurrence (all P<0.03). At competing risks analysis, recurrence rate and OCM were 7.3% and 1.3% vs. 25% and 7.2% vs. 19.9% and 19.9% for PN, RFA and Cryo, respectively.

CONCLUSIONS

PN and Cryo showed similar RFS rates in patients with non-clear cell RCC and with renal mass <2cm.

Ablation of Small Renal Masses

Renal cell carcinoma is most commonly diagnosed in the sixth or seventh decade of life. Historically, surgical extirpation was the gold standard treatment option for small renal masses. However, given the comorbidities in this elderly population, not all patients are candidates for surgery. The development of minimally invasive ablative therapies has solved the surgical dilemma in this patient population. Furthermore, the 2017 American Urological Association guidelines recommends consideration of percutaneous image guided thermal ablation as a treatment option for masses smaller than 3 cm even in healthy individuals. Percutaneous image guided thermal ablation is an attractive treatment option providing excellent local tumor control, fewer complications, better preservation of the renal functions, faster recovery and shorter hospital stay. Various ablative modalities are available in clinical practice. This includes radiofrequency ablation, cryoablation, microwave ablation, irreversible electroporation, high intensity focused ultrasound, and laser ablation. In this review, we focus on the most commonly used modalities including radiofrequency ablation and cryoablation and to a lesser extent microwave ablation and irreversible electroporation.

Radiofrequency ablation (RFA) of T1a renal cancer with externally cooled multitined expandable electrodes

INTRODUCTION

To retrospectively evaluate the mid-term outcomes of percutaneous radiofrequency ablation (RFA) with multitined expandable electrodes externally cooled with saline solution in patients with T1a renal cell carcinoma (RCC).

MATERIALS AND METHODS

In this retrospective study, we evaluated 39 RCC in 35 patients treated with CT-guided RFA in 41 procedures (2011-2017). All patients were staged T1a, N0, M0 prior to RFA. Mean tumor size was 24.48 mm. A 4-tined expandable RFA electrode cooled with pump-circulating saline was used. Efficacy was evaluated verifying complete tumor necrosis (no contrast enhancement on imaging) at the end of the procedure and on subsequent controls. Follow-up observation period was 5 years. Minor/major complications, hospitalization days, serum creatinine and GFR pre- and post-RFA (compared using paired t test) and post-operative pain (evaluated with NRS after treatment) were considered as safety indicators. Overall survival was also calculated (Kaplan-Meier method).

RESULTS

Of 35 patients, 30/35 had 1 treatment (primary effectiveness rate 86%), 4/35 had 2 treatments and 1/35 had 3 treatments for residual disease. There were no relapses and no mid-long-term complications; 3 minor (8%) and 1 major (2.7%) complications during perioperative period were reported. Mean before and after RFA serum creatinine rates were, respectively, 1.08 mg/dl and 1.11 mg/dl (p value: 0.4117). NRS median value is 0.8. Hospitalization days median value is [2.8 ± 1.9] days. 91.4% of all patients survived, with a median overall survival time of 65 months.

CONCLUSIONS

Mid-term results show that CT-guided RFA with multitined expandable electrodes externally cooled with saline solution is an effective and safe treatment in patients with RCC-staged T1aN0M0. Data reported in our study are in line with data reported in the literature from patients treated with other devices.

Imaging of Small Renal Masses before and after Thermal Ablation

Thermal ablation of small renal masses is increasingly accepted as an alternative to partial nephrectomy, particularly in patients with multiple comorbidities. Many professional societies support this alternate treatment with updated guidelines. Before performing thermal ablation, it is important to stratify risk and assess technical feasibility by evaluating tumor imaging features such as size, location, and centrality. Routine postablation imaging with CT or MRI is necessary for assessment of residual or recurrent tumor, evidence of complications, or new renal masses outside the ablation zone. The normal spectrum and evolution of findings at CT and MRI include a halo appearance of the ablation zone, ablation zone contraction, and ablation zone calcifications. Tumor recurrence frequently manifests at CT or MRI as new nodular enhancement at the periphery of an expanding ablation zone, although it is normal for the ablation zone to enlarge within the first few months. Recognizing early tumor recurrence is important, as small renal masses are often easily treated with repeat ablations. Potential complications of thermal ablation include vascular injury, urine leak, ureteral stricture, nerve injury, and bowel perforation. The risk of these complications may be related to tumor size and location.^©RSNA, 2019.

Oncologic Outcomes Following Partial Nephrectomy and Percutaneous Ablation for cT1 Renal Masses

BACKGROUND

Long-term data comparing partial nephrectomy (PN) and thermal ablation are lacking.

OBJECTIVE

To update our experience with PN, percutaneous radiofrequency ablation (RFA), and percutaneous cryoablation for cT1 renal masses.

DESIGN, SETTING, AND PARTICIPANTS

A total of 1798 patients with primary cT1N0M0 renal masses treated between 2000 and 2011 at Mayo Clinic were identified.

INTERVENTION

Percutaneous ablation versus PN.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Cancer-specific survival (CSS) was estimated using the Kaplan-Meier method. Local recurrence, metastases, and death from renal cell carcinoma (RCC) were compared with propensity-score-adjusted Cox models.

RESULTS AND LIMITATIONS

Among 1422 cT1a patients, 1055, 180, and 187 underwent PN, RFA, and cryoablation with median clinical follow-up of 9.4, 7.5, and 6.3yr, respectively. Comparisons of RFA with PN resulted in hazard ratios (HRs) of 1.49 (95% confidence interval [CI] 0.55-4.04, p=0.4), 1.46 (95% CI 0.41-5.19, p=0.6), and 1.99 (95% CI 0.29-13.56, p=0.5) for local recurrence, metastases, and death from RCC. Comparisons of cryoablation to PN resulted in HRs of 1.88 (95% CI 0.76-4.66, p=0.18), 0.23 (95% CI 0.03-1.72, p=0.15), and 0.29 (95% CI 0.01-6.11, p=0.4) for these same outcomes. Five-year CSS was 99%, 96%, and 100% for PN, RFA, and cryoablation, respectively. Among 376 cT1b patients, 324 and 52 underwent PN and cryoablation with median clinical follow-up of 8.7 and 6.0yr, respectively. Comparisons of cryoablation with PN resulted in HRs of 1.22 (95% CI 0.33-4.48, p=0.8), 0.95 (95% CI 0.21-4.38, p>0.9), and 1.94 (95% CI 0.42-8.96, p=0.4) for local recurrence, metastases, and death from RCC, respectively. Five-year CSS was 98% and 91% for PN and cryoablation, respectively. Limitations include retrospective review and selection bias.

CONCLUSIONS

With mature follow-up at a single institution, percutaneous ablation appears to have acceptable results for cT1 renal tumors and is appropriate for patients with a contraindication for surgery. For cT1a patients, clinically relevant differences between PN and ablation are unlikely, and treatment choice should involve shared decision making. For cT1b patients, death from RCC was more common with cryoablation, and large differences in this outcome cannot be ruled out. Further research is needed to confirm the oncologic effectiveness of cryoablation in the cT1b setting.

PATIENT SUMMARY

With appropriate patient triage, partial nephrectomy and percutaneous ablation can be used to treat cT1 renal masses, although additional follow-up and further study are still needed.

Yield of Routine Image-Guided Biopsy of Renal Mass Thermal Ablation Zones: 11-Year Experience

PURPOSE

To determine the yield of routine image-guided core biopsy of renal cell carcinoma (RCC) thermal ablation zones.

METHODS

Institutional review board approval was obtained for this Health Insurance Portability and Accountability Act-compliant quality improvement effort. Routine core biopsy of RCC ablation zones was performed 2 months postablation from July 2003 to December 2014. Routine nicotinamide adenine dinucleotide staining was performed by specialized genitourinary pathologists to assess cell viability. The original purpose of performing routine postablation biopsy was to verify, in addition to imaging, whether the mass was completely treated. Imaging was stratified as negative, indeterminate, or positive for viable malignancy. Histology was stratified as negative, indeterminate, positive, or nondiagnostic for viable malignancy. Histology results were compared to prebiopsy imaging findings.

RESULTS

Routine ablation zone biopsy was performed after 50% (146/292) of index ablations (24 cryoablations, 122 radiofrequency ablations), and postablation imaging was performed more often with multiphasic computed tomography than magnetic resonance imaging (100 vs 46, p < 0.0001). When imaging was negative (n = 117), biopsy added no additional information (92% [n = 108] negative, 0.9% [n = 1] indeterminate, 7% [n = 8] nondiagnostic). When imaging was indeterminate (n = 19), 11% (n = 2) of biopsies had viable RCC and 89% (n = 17) were negative. When imaging was positive, biopsy detected viable neoplasm in only 10% (1/10) of cases; 80% (8/10) were negative and 10% (1/10) were nondiagnostic.

CONCLUSION

Routine biopsy of renal ablation zones to validate postablation imaging results was not value-added and therefore was discontinued at the study institution.

Renal tumor structured reporting including nephrometry score and beyond: what the urologist and interventional radiologist need to know

The purpose of this paper is to describe cross-sectional imaging anatomic and morphologic parameters of solid renal tumors that urologists and interventional radiologists need for precise management, review the commonly used terms and descriptors of those parameters, and suggest a comprehensive reporting system for detected masses.

Efficacy of percutaneous radiofrequency ablation may vary with clear cell renal cell cancer histologic subtype

PURPOSE

The purpose of the study is to determine if clear cell renal cell cancer (RCC) subtype predicts efficacy in percutaneous radiofrequency (RF) ablation of RCC.

METHODS AND MATERIALS

Patients who underwent percutaneous RF ablation for histologically proven RCC subtypes were retrospectively reviewed. Group comparisons were done using univariate and multivariate logistic regression analysis to determine factors impacting primary, secondary, and total technique effectiveness. A p value less than 0.05 was considered significant.

RESULTS

One hundred pathologically proven RCC lesions in 84 patients were analyzed. The median (mean) follow-up was 24 (27) months (range 1-106 months). Overall RF ablation primary, secondary and total technique effectiveness was 86%, 9%, and 95%, respectively. Clear cell subtype demonstrated worse treatment efficacy with primary, secondary, and total technique effectiveness of 42/55 (76.4%), 8/55 (14.5%), and 50/55 (90.9%), respectively. Non-clear cell subtypes had primary, secondary, and total technique effectiveness of 44/45(97.8%), 1/45 (2.2%), 45/45 (100%), respectively. The difference in primary (p = 0.002), secondary (p = 0.032), and total (p = 0.038) technique effectiveness between the two groups was statistically significant.

CONCLUSION

Clear cell RCC was a novel predictor of primary, secondary, and total technique efficacy in the percutaneous RF ablation of clear cell RCC.

Recurrent renal cell carcinoma following nephrectomy and ablation therapy: Radiology perspective

Renal cell carcinoma (RCC) is the most common renal malignancy, accounting for approximately 2% of adult malignancies and 4% of new cancer cases in the United States every year. Imaging guided ablative therapy, including radiofrequency (RF) ablation, cryotherapy and microwave has gained popularity over the last decade in treatment of small tumors. Antiangiogenic therapy has set itself to be the standard of care for many patients with metastasis these days. With hope for more research, survival rates of metastatic RCC may increase from a current 2-year survival rate of approximately 20%. Variation in imaging surveillance protocol in terms of frequency, modality, and duration is noted among guidelines developed by several organizations. In this review article, we will discuss follow-up imaging protocols, patterns of RCC recurrence following different modalities of treatment, imaging appearance, as well as usual and unusual sites of metastatic disease.

Outcomes of Radiofrequency Ablation for Kidney Cancer

BACKGROUND

The incidence of small (< 4 cm) solid enhancing renal masses has been rising, and the majority (60% to 80%) of these tumors are renal cell carcinomas (RCCs) when pathologic analysis is performed. Needle ablation for small incidental renal masses is an attractive therapeutic option. Reasons include its decreased morbidity, shorter convalescence, and the ability to avert the higher risk of extirpative surgery in an aging patient population. Radiofrequency ablation (RFA) is a thoroughly studied needle ablative method used for RCC.

METHODS

The current published literature on renal tumor RFA was reviewed. The in vitro experiments, animal studies and clinical experience with RFA for treatment of small RCCs were analyzed and various controversies in renal RFA are presented for discussion.

RESULTS

Percutaneous and laparoscopic renal RFA can be safely performed and can eradicate small RCCs with cancer specific survival rates over 90% to 95% in many series. While long-term (5 years or greater) cancer control data are not yet available, these intermediate-term results are similar to those achieved with traditional nephron-sparing surgical options. However, the optimal method to perform RFA for renal masses is still evolving.

CONCLUSIONS

While long-term cancer control data are not yet available, the current literature suggests that RFA can effectively eradicate small RCCs. Further research is needed to elucidate the influence of various treatment variables, including impedance vs temperature-controlled RFA, sonographic vs computed tomographic guidance, general anesthetic vs conscious sedation, and radiologist vs urologist delivery of renal RFA.

Image-Guided Percutaneous Radiofrequency Ablation of Central Renal Cell Carcinoma: Assessment of Clinical Efficacy and Safety in 31 Tumors

PURPOSE

To assess clinical efficacy and safety of image-guided percutaneous radiofrequency (RF) ablation of central renal cell carcinoma with adjunctive pyeloperfusion.

MATERIALS AND METHODS

Patients with central renal tumors who underwent percutaneous RF ablation between 2005 and 2010 were retrospectively evaluated. Thirty patients with 31 central renal tumors underwent 39 RF ablation sessions. Mean tumor diameter was 3.7 cm (range, 2-7 cm). Median distance between tumor and renal pelvis was 5 mm (range, 0-15 mm). Pyeloperfusion was performed in 27 patients (27/30; 90%). Contrast-enhanced CT or MR imaging was performed to evaluate treatment response.

RESULTS

Technical success of RF ablation was achieved in 38/39 (97.4%) ablation sessions. Primary efficacy was 83.9% (26/31) on first follow-up imaging. One (3.2%) case of local tumor progression was detected 6 months after initial ablation. Secondary efficacy was 96.8% (30/31) after repeat RF ablation for residual tumor or local tumor progression. Median follow-up was 88 months (mean 82.6 mo ± 30.7; range, 9-121 mo). Major complications occurred in 5/39 (12.8%) RF ablation sessions. Complications were significantly higher for tumors located within 5 mm of the renal pelvis or 0 mm of a major calyx (28.6% vs 4.0%; P < .05). Overall survival was 96.0% (95% CI, 88.4%-100.0%), and progression-free survival at 5 years was 80.9% (95% CI, 65.8%-95.9%).

CONCLUSION

Image-guided percutaneous RF ablation combined with pyeloperfusion has satisfactory clinical efficacy in treating central renal tumors. Although clinically effective, RF ablation of central tumors may also be associated with significant major complications.

Decision Making: Thermal Ablation Options for Small Renal Masses

Renal cell carcinoma is a relatively common tumor, with an estimated 63,000 new cases being diagnosed in the United States in 2016. Surgery, be it with partial or total nephrectomy, is considered the mainstay of treatment for many patients. However, those patients with small renal masses, typically less than 3 to 4 cm in size who are deemed unsuitable for surgery, may be suitable for percutaneous thermal ablation. We review the various treatment modalities, including radiofrequency ablation, microwave ablation, and cryoablation; discuss the advantages and disadvantages of each method; and review the latest data concerning the performance of the various ablative modalities compared with each other, and compared with surgery.

Neutrophil-to-lymphocyte ratio as an independent predictor for survival in patients with localized clear cell renal cell carcinoma after radiofrequency ablation: a propensity score matching analysis

OBJECTIVE

To investigate the role of neutrophil-to-lymphocyte ratio as a prognostic indicator in patients with localized clear cell renal cell carcinoma treated with radiofrequency ablation.

PATIENTS AND METHODS

We retrospectively analyzed data from patients with renal cell carcinoma who underwent radiofrequency ablation from 2006 to 2013. The Kaplan-Meier method was used to generate the survival curves according to different categories of neutrophil-to-lymphocyte ratio. Relationships between preoperative neutrophil-to-lymphocyte ratio or the change of neutrophil-to-lymphocyte ratio and survival were evaluated with multivariable Cox proportional hazards regression analysis. A propensity score matching analysis was carried out to avoid confounding bias.

RESULTS

A total of 185 patients were included in present study. When stratified by preoperative neutrophil-to-lymphocyte ratio cutoff value of 2.79, 5-year recurrence-free survival, 5-year disease-free survival, and 5-year overall survival rates of neutrophil-to-lymphocyte ratio <2.79 versus ≥2.79 were 100, 98.5, and 99.2% versus 80.5, 72.6, and 90.6%, respectively (P < 0.001, P < 0.001, P = 0.003). In terms of propensity score matching analysis, 5-year recurrence-free survival, 5-year disease-free survival, and 5-year overall survival rates of neutrophil-to-lymphocyte ratio <2.79 versus ≥2.79 were 100, 97.9, and 100% versus 82.3, 73.4, and 89.4%, respectively (P = 0.003, P = 0.001, P = 0.022). When combining preoperative neutrophil-to-lymphocyte ratio with the change of neutrophil-to-lymphocyte ratio, patients with both preoperative neutrophil-to-lymphocyte ratio ≥2.79 and the change of neutrophil-to-lymphocyte ratio ≥0.40 had the worst disease-free survival. Results of multivariable analysis showed that preoperative neutrophil-to-lymphocyte ratio and the change of neutrophil-to-lymphocyte ratio correlated with cancer relapse remarkably.

CONCLUSIONS

High preoperative neutrophil-to-lymphocyte ratio and elevated postoperative neutrophil-to-lymphocyte ratio are associated with significant increase in risk of local recurrence as well as distant metastasis. The combination of neutrophil-to-lymphocyte ratio with the other prognostic indicators can be applied in the evaluation of relapse risk in patients with clear cell renal cell carcinoma after radiofrequency ablation.

Laparoscopic Radiofrequency Ablation versus Partial Nephrectomy for cT1a Renal Tumors: Long-Term Outcome of 179 Patients

OBJECTIVES

To compare the long-term functional and oncological results between laparoscopic radiofrequency ablation (LRFA) and laparoscopic partial nephrectomy (LPN) in selected clinical T1a (cT1a) renal tumor patients.

METHODS

We retrospectively analyzed the medical records of patients with cT1a renal tumors who had LRFA or LPN at our institution between February 2006 and February 2015. Student's t test was used to compare the perioperative data between the two groups. Survival analyses were calculated using the Kaplan-Meier method.

RESULTS

A total of 179 patients were included in the study. Patients in the LRFA cohort were significantly older and had higher American Society of Anesthesiologists sore than in the LPN cohort. The LRFA group had a significantly lower mean blood loss than the LPN group (p = 0.03). The percent decrease of GFR in the LRFA group was significantly lower than in the LPN group (p = 0.021). The 5-year overall, cancer-specific and disease-free survival were 93.3 vs. 94.6%, 98.0 vs. 98.5% and 97.1 vs. 97.3%, for LRFA and LPN, respectively (all p value >0.05).

CONCLUSIONS

The excellent perioperative results, long-term functional and oncological outcomes of LRFA confirm that this technique is safe, nephron sparing and oncologically effective for the treatment of cT1a renal tumors.

Percutaneous Renal Tumor Ablation: Radiation Exposure During Cryoablation and Radiofrequency Ablation

INTRODUCTION

Once reserved solely for non-surgical cases, percutaneous ablation is becoming an increasingly popular treatment option for a wider array of patients with small renal masses and the radiation risk needs to be better defined as this transition continues.

MATERIALS AND METHODS

Retrospective review of our renal tumor ablation database revealed 425 patients who underwent percutaneous ablation for treatment of 455 renal tumors over a 5-year time period. Imparted radiation dose information was reviewed for each procedure and converted to effective patient dose and skin dose using established techniques. Statistical analysis was performed with each ablative technique.

RESULTS

For the 331 cryoablation procedures, the mean DLP was 6987 mGycm (SD = 2861) resulting in a mean effective dose of 104.7 mSv (SD = 43.5) and the mean CTDIvol was 558 mGy (SD = 439) resulting in a mean skin dose of 563.2 mGy (SD = 344.1). For the 124 RFA procedures, the mean DLP was 3485 mGycm (SD = 1630) resulting in a mean effective dose of 50.3 mSv (SD = 24.0) and the mean CTDIvol was 232 mGy (SD = 149) resulting in a mean skin dose of 233.2 mGy (SD = 117.4). The difference in patient radiation exposure between the two renal ablation techniques was statistically significant (p < 0.001).

CONCLUSION

Both cryoablation and RFA imparted an average skin dose that was well below the 2 Gy deterministic threshold for appreciable sequela. Renal tumor cryoablation resulted in a mean skin and effective radiation dose more than twice that for RFA. The radiation exposure for both renal tumor ablation techniques was at the high end of the medical imaging radiation dose spectrum.

The Comparison of R.E.N.A.L., PADUA and Centrality Index Score in Predicting Perioperative Outcomes and Complications after Laparoscopic Radio Frequency Ablation of Renal Tumors

PURPOSE

We assessed the association between the R.E.N.A.L., PADUA and centrality index scores and perioperative outcomes, and determined the efficacy of each scoring system over the simple parameter of tumor size.

MATERIALS AND METHODS

We conducted a retrospective review of the records of patients who underwent laparoscopic radio frequency ablation of renal tumors from February 2006 to April 2014 at our institution. Tumors were categorized using the R.E.N.A.L., PADUA and centrality index score, which were determined by analyzing preoperative imaging. The relationships between each variable and change in glomerular filtration rate, estimated blood loss, operative time and postoperative complications were examined.

RESULTS

Laparoscopic radio frequency ablation was performed in 215 selected patients with preoperative imaging available. The interclass correlations coefficient of the 3 observers was 0.87, 0.84 and 0.82 for the C-Index, the R.E.N.A.L. and the PADUA scoring system, respectively. R.E.N.A.L. score, PADUA score and PADUA complexity were significantly associated with postoperative complications (p=0.040, 0.015 and 0.006, respectively). However, major complications were only associated with high PADUA complexity (chi-square 23.851, p <0.05). Each scoring system had a significant association with operative time and estimated blood loss (p <0.05), except that the C-index score had no relationship with estimated blood loss (p=0.083). The accuracy of each scoring system in predicting perioperative outcomes and postoperative complications was superior to that of tumor size.

CONCLUSIONS

Each scoring system has an advantage over tumor size in describing tumor complexity and may help with surgical decision making. Further studies are required to validate their efficacy in evaluating the intraoperative and postoperative results after renal laparoscopic radio frequency ablation.

Efficacy, safety and effectiveness of image-guided percutaneous microwave ablation in cystic renal lesions Bosniak III or IV after 24 months follow up

PURPOSE OF THE STUDY

The aim of the study was to assess the efficacy, safety and effectiveness of percutaneous image-guided microwave ablation (MWA) in Bosniak category III or IV cystic renal lesions after 24 months follow-up duration.

METHODS

Between May 2008 and December 2012, computed tomography (CT)- or ultrasound (US)-guided MWA was performed in 6 patients with 7 cystic renal lesions (range 13.8-27 mm, mean 17.02 mm, SD 8.5 mm) Bosniak category III or IV. The number of treatment sessions, treatment results, lesion size changes and complications were evaluated. Technical success (TS), technical effectiveness (TE), local tumor progression rate (LTPR), cancer-specific survival rate (CSSR) and overall survival rate (OSR) were computed.

MAIN FINDINGS

TS was 100% (7/7) and TE was 100%; LTPR was 0%; CSSR and OSR were 100%. No major complications were observed.

CONCLUSION

Our preliminary experience with MWA shows a potential role for US/CT-guided percutaneous MWA in treating Bosniak category III or IV cystic renal lesions, as a safe approach to treat selected patients not suitable for surgery.

Comparison of partial nephrectomy and percutaneous ablation for cT1 renal masses

BACKGROUND

Partial nephrectomy (PN) is a preferred treatment for cT1 renal masses, whereas thermal ablation represents an alternative nephron-sparing option, albeit with higher reported rates of recurrence.

OBJECTIVE

To review our experience with PN, percutaneous radiofrequency ablation (RFA), and percutaneous cryoablation for cT1 renal masses.

DESIGN, SETTING, AND PARTICIPANTS

A total of 1803 patients with primary cT1N0M0 renal masses treated between 2000 and 2011 were identified from the prospectively maintained Mayo Clinic Renal Tumor Registry.

INTERVENTION

PN compared with percutaneous ablation.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Local recurrence-free, metastases-free, and overall survival rates were estimated using the Kaplan-Meier method and compared with log-rank tests.

RESULTS AND LIMITATIONS

Of the 1424 cT1a patients, 1057 underwent PN, 180 underwent RFA, and 187 underwent cryoablation. In this cohort, local recurrence-free survival was similar among the three treatments (p=0.49), whereas metastases-free survival was significantly better after PN (p=0.005) and cryoablation (p=0.021) when compared with RFA. Of the 379 cT1b patients, 326 patients underwent PN, and 53 patients were managed with cryoablation (8 RFA patients were excluded). In this cohort, local recurrence-free survival (p=0.81) and metastases-free survival (p=0.45) were similar between PN and cryoablation. In both the cT1a and cT1b groups, PN patients were significantly younger, with lower Charlson scores and had superior overall survival (p<0.001 for all). Limitations include retrospective review and selection bias.

CONCLUSIONS

In a large cohort of sporadic cT1 renal masses, we observed that recurrence-free survival was similar for PN and percutaneous ablation patients. Metastases-free survival was superior for PN and cryoablation patients when compared with RFA for cT1a patients. Overall survival was superior after PN, likely because of selection bias. If these results were validated, an update to clinical guidelines would be warranted.

PATIENT SUMMARY

Partial nephrectomy and percutaneous ablation for small (<7-cm) and localized renal masses are associated with similar rates of local recurrence.

Radio frequency ablation versus partial nephrectomy for clinical T1b renal cell carcinoma: long-term clinical and oncologic outcomes

PURPOSE

We compared outcomes in patients treated with radio frequency ablation or partial nephrectomy for clinical cT1b renal cell carcinoma.

MATERIALS AND METHODS

We retrospectively reviewed the records of all patients who underwent radio frequency ablation or nephrectomy between February 2006 and December 2010. Radiographic followup with contrast imaging was performed 7 days, 3 and 6 months, and every 6 months thereafter after radio frequency ablation sequentially. The followup protocol for partial nephrectomy was every 6 months in the initial 3 years and annually thereafter. The Kaplan-Meier method was used to generate survival curves, which were compared with the log rank test. Multivariable regression analysis was done to determine predictors of survival.

RESULTS

A total of 56 patients who met selection criteria were included in study. Patients in the radio frequency ablation group had relatively higher mean age and a higher mean ASA® score than those in the partial nephrectomy group. Mean tumor diameter was significantly larger in the partial nephrectomy cohort. For radio frequency ablation vs partial nephrectomy 5-year overall, cancer specific and disease-free survival was 85.5% (95% CI 72.2-98.8) vs 96.6% (95% CI 95.9-97.3), 92.6% (95% CI 82.4-98.1) vs 96.6% (95% CI 95.9-97.3) and 81.0% (95% CI 66.2-95.8) vs 89.7% (95% CI 78.5-97.9), respectively. The percent decrease in the glomerular filtration rate was significantly lower in the radio frequency ablation group at early and last followup.

CONCLUSIONS

In appropriately selected patients with stage cT1b renal cell carcinoma radio frequency ablation is an effective treatment option that provides 5-year overall, cancer specific and disease-free survival comparable to that of partial nephrectomy as well as better renal function preservation than partial nephrectomy.

Percutaneous ablation of the small renal mass-techniques and outcomes

An increasing number of T1a renal cell carcinomas are being diagnosed in recent years, in part due to incidental detection from the increased use of cross-sectional imaging. Although partial nephrectomy is still considered the primary treatment for these small renal masses, percutaneous ablation is now being performed as a standard therapeutic, nephron-sparing approach in patients who are poor surgical candidates. Clinical studies to date have demonstrated that percutaneous ablation is an effective therapy with acceptable outcomes and low risk in the appropriate clinical settings. This article will review various clinical aspects regarding the percutaneous ablation of small renal masses, including patient selection, preprocedural preparations, and the procedural considerations of commonly employed ablative technologies. Specific techniques such as radiofrequency ablation, cryoablation, microwave ablation, irreversible electroporation, and high-intensity focused ultrasound will be addressed in detail. In addition, the technical and oncologic outcomes of percutaneous ablation will be discussed and referenced to that of partial nephrectomy.

Percutaneous ablation for small renal masses-imaging follow-up

Image-guided percutaneous thermal ablation is a safe and effective nephron-sparing alternative to surgical resection for the treatment of small renal tumors. Assessment of treatment efficacy relies heavily on interval follow-up imaging after treatment. Contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) both play a pivotal role in evaluating the treatment zone, identifying residual tumor, and detecting early and delayed procedure-related complications. This article discusses a surveillance imaging protocol for patients who undergo percutaneous thermal ablation of renal tumors, and also illustrates the typical appearances of both successfully treated tumors and residual disease on contrast-enhanced CT or MRI. In addition, it discusses the imaging appearance of potential early and delayed treatment-related complications to facilitate their prompt detection and management.

Cancer-free survival and local tumor control after impendence-based radiofrequency ablation of biopsy-proven renal cell carcinomas with a minimum of 1-year follow-up

OBJECTIVES

There are numerous reports describing the use of radiofrequency ablation (RFA) to treat renal cell carcinoma. Many series, however, describe heterogeneous populations, lack histologic descriptions, use various RFA systems, and indicate tumor destruction by different ablation end points. This study examined the outcomes of computed tomography-guided, impedance-based RFA of biopsy-proven renal cell carcinoma clinically staged as T1a with a minimum of 1 year of postablation follow-up.

METHODS AND MATERIALS

This retrospective study identified all consecutive patients who had undergone renal RFA since May 2005 at our institution. Patients without biopsy-proven renal cell carcinoma (RCCa) were excluded. Of the patients who met these criteria, evaluation was limited to patients with a minimum of 12 months of follow-up. Data collected from the patients' electronic medical and radiologic records included demographic data, tumor-related data, procedural details, and clinical follow-up visits.

RESULTS

A total of 39 patients (46 lesions) met the inclusion criteria. The mean tumor diameter was 2.6 cm (range: 1.2-4.0 cm). The most common histologies were clear cell (n = 27) and papillary (n = 16) renal cancer. The lesion location was equally divided between upper pole (n = 16), middle pole (n = 16), and lower pole (n = 14). Overall, 83% of the tumors were exophytic. No residual or recurrent enhancing mass was identified in the ablation bed on post-RFA imaging during the mean follow-up period of 35.3 months (range: 12-83). All patients were treated in a single encounter and no lesion required a second ablation; technical success (absence of residual tumor) on the initial post-RFA imaging study was 46 of 46 (100%). Clinical success was achieved in 45 of 46 lesions (98%); residual, viable tumor was found in a pretransplant nephrectomy specimen on postprocedure day 127. The mean cancer-free survival was 36.2 months. Comparison of preablation and postablation renal function found no statistically significant change.

CONCLUSIONS

The consistent outcomes in our post-RFA imaging and clinical surveillance allow us to offer image-guided ablation to patients with T1a RCCa as a valid treatment option offering long-term cancer-free survival. Impedance-based RFA in a carefully selected patient population with T1a RCCa is a reliable treatment option, with disease-free survival rates that are comparable to partial nephrectomy.

Systematic review and meta-analysis of thermal ablation versus surgical nephrectomy for small renal tumours

PURPOSE

A systematic review was undertaken to provide a meta-analysis of clinical trials comparing thermal ablation with surgical nephrectomy for small renal tumours.

METHODS

PubMed (MEDLINE), EMBASE, AMED, and Scopus were searched in August 2013 for eligible prospective or retrospective comparative trials following the PRISMA selection process. Thermal ablation was compared with surgical nephrectomy. Quality of included studies was assessed on the Newcastle-Ottawa Scale (NOS). The primary endpoint was disease-free survival and was analyzed on the log-hazard scale. Secondary outcome measures included complications, local recurrence, and decline of renal function. Hazard ratios (HR) and risk ratios (RR) were calculated with a random effects model, and meta-regression analysis was performed to explore clinical heterogeneity.

RESULTS

Six clinical trials (1 randomized and 5 cohort; 6-8 stars on the NOS scale) involving 587 patients with small renal tumors (mean size 2.5 cm) treated with either thermal ablation (percutaneous or laparoscopic application of radiofrequency or microwave) or surgical nephrectomy (open or laparoscopic) were analyzed. Overall complication rate was significantly lower in the ablation group (7.4 vs. 11%; RR: 0.55, 95% confidence interval [CI]: 0.31-0.97, p = 0.04). Postoperative decline of eGFR was higher in case of nephrectomy (mean difference: -14.6 ml/min/1.73 m(2), 95% CI: -27.96 to -1.23, p = 0.03). Local recurrence rate was the same in both groups (3.6 vs. 3.6%; RR: 0.92, 95% CI: 0.4-2.14, p = 0.79) and disease-free survival also was similar up to 5 years (HR: 1.04, 95% CI: 0.48-2.24, p = 0.92).

CONCLUSIONS

Thermal ablation of small renal masses produces oncologic outcomes similar to surgical nephrectomy and is associated with significantly lower overall complication rates and a significantly less decline of renal function. More randomized, controlled trials are necessary.

Percutaneous radiofrequency ablation: minimally invasive therapy for renal tumors

Currently, up to 60% of renal tumors are detected incidentally by abdominal imaging. Most of these tumors are small and localized to the kidney. Owing to the shift to lower stage at diagnosis, radical nephrectomy has fallen out of favor and has been replaced by nephron-sparing surgery. Currently, partial nephrectomy is the treatment of choice for patients with small renal tumors. As the trend towards less invasive therapy continues, laparoscopic and percutaneous ablation techniques have gained popularity for the treatment of renal tumors in patients who are high-risk surgical candidates, or have a solitary kidney, limited renal function or multifocal disease. Percutaneous radiofrequency ablation is a safe, minimally invasive treatment option for those patients.

Radiofrequency ablation of small renal tumors

Technological improvements have led to increased diagnosis of small renal tumors and to the development of minimally invasive treatments for these tumors. As a minimally invasive ablative treatment, radiofrequency ablation shows promise as a therapeutic option for selected patients. By creating heat using radiofrequency waves, radiofrequency ablation leads to controlled thermal ablation within the target tissue. Experimental studies have shown radiofrequency ablation to be safe and reproducible. Clinical studies are ongoing but early evidence suggests that radiofrequency ablation is safe and oncologic results are encouraging. With further development of monitoring techniques and additional maturation of oncologic data, radiofrequency ablation may become a standard treatment option for patients with small renal tumors.

Comparison of laparoscopic radiofrequency ablation and open partial nephrectomy in patients with a small renal mass

Purpose

We have performed both open partial nephrectomy (OPN) and laparoscopic radiofrequency ablation (RFA) on selected patients since January 2007 and have been following these patients through serial laboratory assessments and computed tomography (CT). The purpose of the present study was to evaluate long-term oncologic outcomes and renal function status for laparoscopic RFA versus OPN at a minimum follow-up of 3 years.

Materials and Methods

A total of 55 patients with exophytic, single small renal masses were treated with either OPN (n=14) or laparoscopic RFA (n=41) by a single surgeon. The indications for laparoscopic RFA were as follows: 1) cases with the greatest dimension of the renal mass <3 cm, and 2) cases in which the collecting system, renal calyx, and great vessels were free from the tumor margins by 1 cm.

Results

The estimated blood loss (EBL), the operation time, and the mean number of hospital days was significantly lower in the laparoscopic RFA group than in the OPN group. Oncologic data did not differ significantly between the two groups. Creatine clearance levels did not differ significantly compared with those before the operation in either group.

Conclusions

Our data suggest excellent therapeutic outcomes with laparoscopic RFA with achievement of effective operative times, hospital stays, and EBL compared with OPN. According to our indications for laparoscopic RFA, laparoscopic RFA is an effective minimally invasive therapy for the treatment of small renal masses, yielding oncologic outcomes and renal function equivalent to those of OPN.

Percutaneous radiofrequency ablation of small renal tumours in patients with a single functioning kidney: long-term results

OBJECTIVES

To evaluate the long-term results of percutaneous radiofrequency ablation (RFA) of small renal tumours in patients with a single functioning kidney (SFK).

METHODS

This is a single-centre prospective study. Patients with an SFK and a tumour smaller than 3.5 cm, treated with RFA over a 7.5-year period, were included. Nineteen consecutive patients (12 male), aged between 33 and 83 years (mean 61.4), were treated for 23 lesions. Primary endpoints were technical success and tumour recurrence rate. Secondary endpoints were the deterioration of renal function and overall survival rate.

RESULTS

The mean follow-up was 56.1 months (range 36-102). Primary technical success was 100 %. There were no major peri-procedural complications. In two cases, minor complications occurred. There was no significant difference between the baseline glomerular filtration rate (GFR) and GFR at 3, 12 and 24 months post-procedure. In four lesions (17 %), recurrence was detected and an additional RFA session was performed. None of the patients developed renal failure during their lifetime. Three of the patients died because of other reasons.

CONCLUSIONS

Percutaneous RFA of small renal tumours in patients with an SFK offers very satisfactory long-term results regarding preservation of renal function, local tumour control and overall survival.

KEY POINTS

• Tumour in a single functioning kidney requires minimally invasive treatment. • Radiofrequency ablation plays an established role in managing small renal tumours. • Long-term results of radiofrequency ablation have shown satisfactory local tumour control. • Long-term results have also shown that renal function may be preserved.

Clinically-translated silica nanoparticles as dual-modality cancer-targeted probes for image-guided surgery and interventions

Early diagnosis and treatment of melanoma are essential to minimizing morbidity and mortality. The presence of lymph node metastases is a vital prognostic predictor, and accurate identification by imaging has important implications for disease staging, prognosis, and clinical outcome. Sentinel lymph node (SLN) mapping procedures are limited by a lack of intraoperative visualization tools that can aid accurate determination of disease spread and delineate nodes from adjacent critical neural and vascular structures. Newer methods for circumventing these issues can exploit a variety of imaging tools, including biocompatible particle-based platforms coupled with portable device technologies for use with image-guided surgical and interventional procedures. We describe herein a clinically-translated, integrin-targeting platform for use with both PET and optical imaging that meets a number of key design criteria for improving SLN tissue localization and retention, target-to-background ratios, and clearance from the site of injection and the body. The use of such agents for selectively probing critical cancer targets may elucidate important insights into cellular and molecular processes that govern metastatic disease spread. Coupled with portable, real-time optical camera systems, we show that pre-operative PET imaging findings for mapping metastatic disease in clinically-relevant larger-animal models can be readily translated into the intraoperative setting for direct visualization of the draining tumor lymphatics and fluorescent SLN/s with histologic correlation. The specificity of this platform, relative to the standard-of-care radiotracer, (18)F-FDG, for potentially discriminating metastatic disease from inflammatory processes is also discussed in the setting of surgically-based or interventionally-driven therapies.

Ten-year experience of percutaneous image-guided radiofrequency ablation of malignant renal tumours in high-risk patients

OBJECTIVES

To evaluate survival and outcomes after percutaneous radiofrequency ablation (RFA) of malignant renal tumours in high-risk patients with long-term follow-up.

METHODS

Between 2002 and 2009, 62 patients (71 tumours), with a median age of 73.5 years (20-87), consecutively treated with RFA under ultrasound or computed tomography guidance for malignant renal tumours were retrospectively selected and prospectively followed until 2012, including 25 patients (40.3 %) with solitary kidney and 7 cystic cancers. Maximal tumour diameters were between 8 and 46 mm (median: 23 mm).

RESULTS

Radiofrequency ablation was technically possible for all patients. Mean follow-up was 38.8 months (range: 18-78 months). Primary and secondary technique effectiveness was 95.2 % and 98.4 % per patient respectively. The rates of local tumour progression and metastatic evolution were 3.2 % and 9.7 % per patient and were associated with tumour size >4 cm (P = 0.005). The disease-free survival rates were 88.3 % and 61.9 % at 3 and 5 years. No significant difference in glomerular filtration rates before and after the procedure was observed (P = 0.107). The major complications rate was 5.9 % per session with an increased risk in the case of central locations (P = 0.006).

CONCLUSIONS

Percutaneous renal RFA appears to be safe and effective with useful nephron-sparing results.

KEY POINTS

• Radiofrequency ablation (RFA) is a well-tolerated technique according to mid-term results. • RFA for malignant renal tumours preserved renal function in high-risk patients. • Mid-term efficacy of RFA was close to that of formal conservative surgery. • Tumour size and central location limit the efficacy and safety of RFA.

Solid renal masses: effectiveness and safety of image-guided percutaneous radiofrequency ablation

With increasing emphasis on minimally invasive nephron-sparing techniques for treatment of renal tumors, image-guided percutaneous radiofrequency ablation (RFA) has emerged as a safe and effective method of tumor eradication that may be performed on an outpatient basis, with relatively low morbidity and mortality. This review addresses the clinical and technical considerations, risks, complications, and currently reported efficacy data pertaining to RFA of renal tumors, as well as the standardized approach to treatment and follow-up currently used in our practice.

Improved outcome of percutaneous radiofrequency ablation in renal cell carcinoma: a retrospective study of intraoperative contrast-enhanced ultrasonography in 73 patients

OBJECTIVES

To evaluate the impact of contrast-enhanced ultrasonography (CEUS) during percutaneous radiofrequency ablation (PRFA) procedure in renal cell carcinoma (RCC).

METHODS

From January 2008 to July 2010, 73 patients with sporadic unilateral RCC were enrolled to our study (57 men and 16 women, age range: 37-78 years, mean age 57.9 years). The diameter of the tumor was 1.7-5.8, 3.4 cm on average. The patients were divided into two groups depending on the intraoperative ultrasonography type: CEUS group and conventional ultrasound group. Patients in CEUS group received CEUS before insertion of the electrode, and the second CEUS was performed right after the initial ablation to dynamically evaluate the images. If there was highly suspicious residue, additional ablation and repeated CEUS were applied. Patients in the conventional ultrasound group received PRFA guided by gray-scale ultrasound. All of these patients received contrast-enhanced computed tomography (CT) examination 7 days after the procedure (patients in CEUS group received CEUS conducted with each CT scan), with subsequent CT and CEUS assessment at 3, 6, and every 6 months thereafter.

RESULTS

The mean follow-up period was 22 months (range: 12-42 months). All tumors were biopsied before RFA. The local tumor control rate was 94.6% (35/37) in the CEUS group and 86.1% (31/36) in the conventional ultrasound group (P < 0.05); the cancer-specific survival rate and the overall survival rate were 100%. The post-RFA (12 months) mean GFR levels were 84.7 ± 27.5 mL/min/1.73 m(2) (P > 0.05, compared with pre-GFR: 86.4 ± 26.2 mL/min/1.73 m(2)) in the CEUS group and 81.9 ± 22.8 mL/min/1.73 m(2) (P > 0.05, compared with pre-GFR: 83.5 ± 23.7 mL/min/1.73 m(2)) in the conventional ultrasound group.

CONCLUSION

Intraoperative CEUS can "real-time" monitor the ablated area during PRFA procedure. This technique can help to achieve a higher success rate compared with conventional ultrasound. No impact of intraoperative CEUS has been found on GFR level.

Radiofrequency ablation of renal tumors: four-year follow-up results in 47 patients

Objective

To retrospectively evaluate the intermediate results of radiofrequency ablation (RFA) of small renal masses (SRMs).

Materials and Methods

Percutaneous or laparoscopic RFA was performed on 48 renal tumors in 47 patients. The follow-up studies included a physical examination, chest radiography, creatinine level, and contrast-enhanced CT or MRI. To confirm the pathologic criteria of complete ablation, 35 patients underwent a follow-up biopsy. Recurrence was defined as contrast enhancement on imaging studies after 3 months, lesion growth at subsequent imaging, or viable cancer cells on follow-up biopsy.

Results

Technical success was achieved in 43 (89.6%) of 48 renal tumors. The mean tumor size was 2.3 cm and the mean follow-up period was 49.6 months. Repeated RFA was necessary in 5 tumors due to incomplete ablation. The overall complication rate was 35.8%, of which 96.2% were mild complications. Serum creatinine levels at 12 months after RFA did not differ from those before RFA (1.28 vs. 1.36 mg/dL). Four patients were found to have recurrence at various follow-up intervals, and distant metastasis was not found in any cases.

Conclusion

RFA appears to be a useful treatment for selected patients with SRMs. Our 4-year follow-up results disclose an excellent therapeutic outcome with RFA, while achieving effective local tumor control.

Complications of radiofrequency ablation of hepatic, pulmonary, and renal neoplasms

Percutaneous thermal ablation has emerged as a viable technique for treatment of numerous solid organ malignancies. As the number of these procedures increases, so do the complications that are seen. Most common complications are generally related to bleeding from the target organ during or after the procedure and from thermal injury to adjacent structures. The nature of these injuries depends on the particular organ being treated, therefore it it best to categorize them this way. We will review the more common complications seen following the ablation of tumors in the liver, kidney, and lung, discuss the clinical presentation associated with each, and suggest precautions to help avoid them in the future. Understanding the potential risks associated with this procedure is critical for treatment planning and fundamental for performing these procedures safely.

Ablative therapies for renal tumors

Owing to an increased use of diagnostic imaging for evaluating patients with other abdominal conditions, incidentally discovered kidney masses now account for a majority of renal tumors. Renal ablative therapy is assuming a more important role in patients with borderline renal impairment. Renal ablation uses heat or cold to bring about cell death. Radiofrequency ablation and cryoablation are two such procedures, and 5-year results are now emerging from both modalities. Renal biopsy at the time of ablation is extremely important in order to establish tissue diagnosis. Real-time temperature monitoring at the time of radiofrequency ablation is very useful to ensure adequacy of ablation.