Effect of Tumor Complexity and Technique on Efficacy and Complications after Percutaneous Microwave Ablation of Stage T1a Renal Cell Carcinoma: A Single-Center, Retrospective Study

Comparison of the Efficacy of Percutaneous Microwave Ablation Therapy versus Laparoscopic Partial Nephrectomy for Early-Stage Renal Tumors

This study aimed to compare the efficacy of percutaneous microwave ablation therapy (MWAT) and laparoscopic partial nephrectomy (LPN) in early-stage renal cell carcinoma (RCC) classified as T1a; a retrospective analysis was conducted on patients treated between January 2017 and November 2023. Oncological outcomes, radiological recurrence, length of stay (LOS), and costs were evaluated. The study included 110 patients, with no significant differences between the two groups regarding residual tumors, local tumor progression, and disease-free survival rates (p > 0.05). The LPN group showed significantly lower pre/postoperative serum urea and creatinine and higher estimated glomerular filtration rate values, whereas the MWA group experienced significantly lower mean costs, complication rates, LOS in the hospital, and procedure durations (p ≤ 0.05). However, post-procedure residual tumors and local tumor progression rates did not differ significantly between the LPN and MWAT groups (p > 0.05). MWAT is as effective as LPN for T1a RCC lesions. In addition, MWAT has lower costs than LPN and is a cost-effective treatment method. Therefore, MWAT minimizes hospital stay and complications and since the oncological results are similar to LPN, it might be considered as the first choice of treatment in young patients.

Ablative Treatments for Small Renal Masses and Management of Recurrences: A Comprehensive Review

This review focuses on ablative techniques for small renal masses (SRMs), including radiofrequency ablation (RFA), cryoablation (CA), microwave ablation (MWA), and irreversible electroporation (IRE), and discusses recurrence management. Through an extensive literature review, we outline the procedures, outcomes, and follow-up strategies associated with each ablative method. The review provides a detailed examination of these techniques-RFA, CA, MWA, and IRE-elucidating their respective outcomes. Recurrence rates vary among them, with RFA and CA showing comparable rates, MWA demonstrating favorable short-term results, and IRE exhibiting promise in experimental stages. For managing recurrences, various strategies are considered, including active surveillance, re-ablation, or salvage surgery. Surveillance is preferred post-RFA and post-CA, due to slow SRM growth, while re-ablation, particularly with RFA and CA, is deemed feasible without additional complications. Salvage surgery emerges as a viable option for larger or resistant tumors. While ablative techniques offer short-term results comparable to surgery, further research is essential to understand their long-term effects fully. Decisions concerning recurrence management should consider individual and tumor-specific factors. Imaging, notably contrast-enhanced ultrasounds, plays a pivotal role in assessing treatment success, emphasizing the necessity of a multidisciplinary approach for optimal outcomes. The lack of randomized trials highlights the need for further research.

Microwave ablation of 105 T1 renal tumors: technique efficacy with a mean follow-up of two years

BACKGROUND

Thermal ablation (TA) with radiofrequency (RFA) or cryoablation (CA) are established treatments for small renal masses (≤4 cm). Microwave ablation (MWA) has several potential benefits (decreased ablation time, less susceptibility to heat-sink, higher lesion temperatures than RFA) but is still considered experimental considering the available small-sample studies with short follow-up.

PURPOSE

To evaluate technique efficacy and complications of our initial experience of renal tumors treated using percutaneous MWA with a curative intent.

MATERIAL AND METHODS

A total of 105 renal tumors (in 93 patients) were treated between April 2014 and August 2017. MWA was performed percutaneously with computed tomography (CT) guidance under conscious sedation (n=82) or full anesthesia. Patients were followed with contrast-enhanced CT scans at six months and yearly thereafter for a minimum of five years. The mean follow-up time was 2.1 years. The percentage of tumors completely ablated in a single session (primary efficacy rate) and those successfully treated after repeat ablation (secondary efficacy rate) were recorded. Patient and tumor characteristics as well as complications were collected retrospectively.

RESULTS

The median patient age was 70 years and median tumor size was 25 mm. Primary efficacy rate was 96.2% (101/105 tumors). After including two residual tumors for a second ablation session, secondary efficacy was 97.1% (102/105). Periprocedural complications were found in 5.2% (5/95) sessions: four Clavien-Dindo I and one Clavien-Dindo IIIa. One postprocedural Clavien-Dindo II complication was found.

CONCLUSION

MWA has high efficacy rates and few complications compared to other TA methods at a mean follow-up of two years.

Computed tomography-guided percutaneous microwave ablation for renal cell carcinoma: evaluating the performance of nephrometry scores

OBJECTIVES

The purpose of the current study is to evaluate the performance of RENAL and mRENAL scores, in the prediction of oncological outcomes in patients treated with microwave ablation (MWA) for (T1) renal cell carcinomas (RCC).

METHODS

Institutional database retrospective research identified 76 patients with a biopsy-proven solitary T1a (84%) or T1b (16%) RCC; all patients underwent CT-guided MWA ablation. Tumor complexity was reviewed by calculating RENAL and mRENAL scores.

RESULTS

The majority of the lesions were exophytic (82.9%), with > 7 mm nearness to the collecting system (53.9%), located posteriorly (73.6%), and lower to polar lines (61.8%). Mean RENAL and mRENAL scores were 5.7 (SD = 1.9) and 6.1 (SD = 2.1) respectively. Progression rates were significantly higher with greater tumor size (> 4 cm), with < 4 mm nearness to the collecting system, for tumors crossing a polar line and with the anterior location. None of the above was associated with complications. RENAL and mRENAL scores were significantly higher in patients with incomplete ablation. The ROC analysis showed the significant prognostic ability of both RENAL and mRENAL scores for progression. In both scores, the optimal cut-off point was 6.5. Univariate Cox regression analysis for progression showed a hazard ratio of 7.73 for the RENAL score and 7.48 for the mRENAL score.

CONCLUSION

The results of the present study show that the risk of progression was higher in patients with RENAL and mRENAL score of > 6.5, in T1b tumors, close to the collective system (< 4 mm), crossing polar lines and anterior location.

CLINICAL RELEVANCE STATEMENT

CT-guided percutaneous MWA is a safe and effective technique for the treatment of T1a renal cell carcinomas. Different morphometric parameters of RCC tumors including RENAL and mRENAL score > 6.5, size, proximity to the collecting system, and crossing of polar lines impact the efficacy of MWA and progression survival rates.

KEY POINTS

• The risk of progression is higher in patients with RENAL and mRENAL score > 6.5, in T1b tumors, close to the collective system (< 4 mm), crossing polar lines and anterior location. • The significant prognostic ability of the mRENAL score for progression was higher than the respective of the RENAL score. • Complications were not associated with any of the above factors.

Microwave ablation of the T1a small renal mass: expanding beyond 3 cm

PURPOSE

To compare the oncological and renal function outcomes for patients receiving microwave ablation (MWA) in tumors < 3 and 3-4 cm.

METHODS

Retrospective analysis of a prospectively maintained database identified patients with < 3 or 3-4 cm renal cancers undergoing MWA. Radiographic follow-up occurred at approximately 6 months post-procedure and annually thereafter. Serum creatinine and estimated glomerular filtration rate (eGFR) were calculated before and 6-months post-MWA. Local recurrence-free survival (LRFS) was estimated using the Kaplan-Meier method. Tumor size was evaluated as a prognostic factor using Cox proportional-hazards regression. Predictors for change in eGFR and chronic kidney disease (CKD) stage were modeled using linear and ordinal logistic regression.

RESULTS

A total of 126 patients fit the inclusion criteria. Overall recurrences were 2/62 (3.2%) and 6/64 (9.4%) for < 3 versus 3-4 cm. Both recurrences in the < 3 cm group were local, 4/6 in the 3-4 cm group were local and 2/6 were metastatic without local progression. For < 3 versus 3-4 cm, cumulative LRFS at 36 months was 94.6% versus 91.4%. Tumor size was not a significant prognostic factor for LRFS. Renal function did not change significantly after MWA. Patient comorbidities and RENAL nephrometry score significantly affected change in CKD.

CONCLUSION

With comparable oncological outcomes, complication rates, and renal function preservation, MWA is a promising management strategy for renal masses of 3-4 cm in select patients. Our findings suggest that current AUA guidelines, which recommend thermal ablation for tumors < 3 cm, may need review to include T1a tumors for MWA, regardless of size.

Radiofrequency Ablation, Cryoablation, and Microwave Ablation for the Treatment of Small Renal Masses: Efficacy and Complications

Over the last two decades the detection rate of small renal masses has increased, due to improving diagnostic accuracy, and nephron-sparing treatments have become the first-choice curative option for small renal masses. As a minimally invasive alternative, thermal ablation has increased in popularity, offering a good clinical outcome and low recurrence rate. Radiofrequency ablation, Cryoablation, and Microwave ablation are the main ablative techniques. All of them are mostly overlapping in term of cancer specific free survival and outcomes. These techniques require imaging study to assess lesions features and to plan the procedure: US, CT, and both of them together are the leading guidance alternatives. Imaging findings guide the interventional radiologist in assessing the risk of complication and possible residual disease after procedure. The purpose of this review is to compare different ablative modalities and different imaging guides, underlining the effectiveness, outcomes, and complications related to each of them, in order to assist the interventional radiologist in choosing the best option for the patient.

Recent Advances in the Management of Localized and Locally Advanced Renal Cell Carcinoma: A Narrative Review

Purpose

To review the current status of surgical and procedural treatments for renal cell carcinoma (RCC), focusing on oncological and functional outcomes, and the use of techniques for advanced disease over the last 10 years.

Findings

Partial nephrectomy (PN) has become the reference standard for most T1 and T2 masses. In cT2 RCC, PN exhibits oncological equivalence and improved functional outcomes compared to radical nephrectomy (RN). Additionally, emerging data suggest that PN may be used to treat cT3a RCC. The robot-assisted platform is increasingly used to treat locally advanced RCC. Studies suggest safety and feasibility of robotic RN and robotic inferior vena cava tumor thrombectomy. Additionally, single-port robot-assisted laparoscopic approaches are comparable to multiport approaches in select patients. Long-term data show that cryoablation, radiofrequency ablation, and microwave ablation are equipotent in management of small renal masses. Emerging data suggest that microwave may effectively treat cT1b masses.

Safety and efficacy of RFA versus MWA for T1a renal cell carcinoma: a propensity score analysis

OBJECTIVES

Percutaneous radiofrequency ablation (RFA) is stated as a treatment option for renal cell carcinoma (RCC) smaller than 4 cm (T1a). Microwave ablation (MWA) is a newer technique and is still considered experimental in some guidelines. The objective of this study was to compare the safety and efficacy of RFA and MWA for the treatment of RCC.

METHODS

Patients with T1a RCC treated by RFA or MWA in two referral centers were retrospectively analyzed. Patient records were evaluated to generate mRENAL nephrometry scores. Local tumor progression (LTP) was considered when new (recurrence) or residual tumor enhancement within/adjacent to the ablation zone was objectified. Differences in LTP-free interval (residual + recurrence) between ablation techniques were assessed with Cox proportional hazards models and propensity score (PS) methods.

RESULTS

In 164 patients, 87 RFAs and 101 MWAs were performed for 188 RCCs. The primary efficacy rate was 92% (80/87) for RFA and 91% (92/101) for MWA. Sixteen patients had residual disease (RFA (n = 7), MWA (n = 9)) and 9 patients developed recurrence (RFA (n = 7), MWA (n = 2)). LTP-free interval was significantly worse for higher mRENAL nephrometry scores. No difference in LTP-free interval was found between RFA and MWA in a model with inverse probability weighting using PS (HR = 0.99, 95% CI 0.35-2.81, p = 0.98) and in a PS-matched dataset with 110 observations (HR = 0.82, 95% CI 0.16-4.31, p = 0.82). Twenty-eight (14.9%) complications (Clavien-Dindo grade I-IVa) occurred (RFA n = 14, MWA n = 14).

CONCLUSION

Primary efficacy for ablation of RCC is high for both RFA and MWA. No differences in efficacy and safety were observed between RFA and MWA.

KEY POINTS

• Both RFA and MWA are safe and effective ablation techniques in the treatment of T1a renal cell carcinomas. • High modified RENAL nephrometry scores are associated with shorter local tumor progression-free interval. • MWA can be used as heat-based ablation technique comparable to RFA for the treatment of T1a renal cell carcinomas.

Split-bolus CT urography after microwave ablation of renal cell carcinoma improves image quality and reduces radiation exposure

OBJECTIVE

To compare image quality and radiation dose between single-bolus 2-phase and split-bolus 1-phase CT Urography (CTU) performed immediately after microwave ablation (MWA) of clinically localized T1 (cT1) RCC.

METHODS

Forty-two consecutive patients (30 M, mean age 67.5 ± 9.0) with cT1 RCC were treated with MWA from 7/2013 to 12/2013 at two academic quaternary-care institutions. Renal parenchymal enhancement, collecting system opacification and distention and size-specific dose estimate (SSDE) were quantified and image quality subjectively assessed on single-bolus 2-phase versus split-bolus 1-phase CTU. Kruskal-Wallis and Pearson's Chi-squared tests were performed to assess differences in continuous and categorical variables, respectively. Two-sample T test with equal variances was used to determine differences in quantitative and qualitative image data.

RESULTS

Median tumor diameter was larger [2.9 cm (IQR 1.7-5.3) vs 3.6 cm (IQR 1.7-5.7), p = 0.01] in the split-bolus cohort. Mean abdominal girth (p = 0.20) was similar. Number of antennas used and unenhanced CTs obtained before and during MWA were similar (p = 0.11-0.32). Renal pelvis opacification (2.5 vs 3.5, p < 0.001) and distention (4 mm vs 8 mm, p < 0.001) were improved and renal enhancement (Right: 127 HU vs 177 HU, p = 0.001; Left: 124 HU vs 185 HU, p < 0.001) was higher for the split-bolus CTU. Image quality was superior for split-bolus CTU (3.2 vs 4.0, p = 0.004). Mean SSDE for the split-bolus CTU was significantly lower [163.9 mGy (SD ± 73.9) vs 36.3 mGy (SD ± 7.7), p < 0.001].

CONCLUSION

Split-bolus CTU immediately after MWA of cT1 RCC offers higher image quality, improved opacification/distention of the collecting system and renal parenchymal enhancement at a lower radiation dose.

Thermal shielding performance of self-healing hydrogel in tumor thermal ablation

Thermal ablation therapy is widely used in the surgical treatment of tumors. Clinically, normal saline is generally used as an insulator to protect adjacent tissues from local high-temperature burns caused by thermal ablation. However, the flow of saline causes fluid loss, requiring frequent injections and complex operation, which is easy to lead to complications such as secondary injury and hematoma. Here, a self-healing chitosan-PEG (CP) hydrogel was proposed as a protective medium to challenge the clinical preparations. Compared with saline and non-self-healing hydrogel F127, CP hydrogel exhibited outstanding thermal shielding performance in the thermal ablation of thyroid nodule in a Beagle dog model. The transient plane source (TPS) method is used to measure thermal properties, including thermal conductivity, thermal diffusivity and specific heat capacity. The thermal shielding mechanism and clinical advantages including operability, biodegradability, and biological safety of self-healing hydrogel are then revealed in-depth. Therefore, self-healing hydrogel can achieve much better thermal management in tumor thermal ablation.

Magnetic Hyperthermia Nanoarchitectonics via Iron Oxide Nanoparticles Stabilised by Oleic Acid: Anti-Tumour Efficiency and Safety Evaluation in Animals with Transplanted Carcinoma

In this study, we developed iron oxide nanoparticles stabilised with oleic acid/sodium oleate that could exert therapeutic effects for curing tumours via magnetic hyperthermia. A suspension of iron oxide nanoparticles was produced and characterised. The toxicity of the synthesised composition was examined in vivo and found to be negligible. Histological examination showed a low local irritant effect and no effect on the morphology of the internal organs. The efficiency of magnetic hyperthermia for the treatment of transplanted Walker 256 carcinoma was evaluated. The tumour was infiltrated with the synthesised particles and then treated with an alternating magnetic field. The survival rate was 85% in the studied therapy group of seven animals, while in the control group (without treatment), all animals died. The physicochemical and pharmaceutical properties of the synthesised fluid and the therapeutic results, as seen in the in vivo experiments, provide insights into therapeutic hyperthermia using injected magnetite nanoparticles.

Variability in personal protective equipment in cross-sectional interventional abdominal radiology practices

Purpose

To determine institutional practice requirements for personal protective equipment (PPE) in cross-sectional interventional radiology (CSIR) procedures among a variety of radiology practices in the USA and Canada.

Methods

Members of the Society of Abdominal Radiology (SAR) CSIR Emerging Technology Commission (ETC) were sent an eight-question survey about what PPE they were required to use during common CSIR procedures: paracentesis, thoracentesis, thyroid fine needle aspiration (FNA), superficial lymph node biopsy, deep lymph node biopsy, solid organ biopsy, and ablation. Types of PPE evaluated were sterile gloves, surgical masks, gowns, surgical hats, eye shields, foot covers, and scrubs.

Results

26/38 surveys were completed by respondents at 20/22 (91%) institutions. The most common PPE was sterile gloves, required by 20/20 (100%) institutions for every procedure. The second most common PPE was masks, required by 14/20 (70%) institutions for superficial and deep procedures and 12/12 (100%) institutions for ablation. Scrubs, sterile gowns, eye shields, and surgical hats were required at nearly all institutions for ablation, whereas approximately half of institutions required their use for deep lymph node and solid organ biopsy. Compared with other types of PPE, required mask and eye shield use showed the greatest increase during the SARS-CoV-2 pandemic.

Conclusion

PPE use during common cross-sectional procedures is widely variable. Given the environmental and financial impact and lack of consensus practice, further studies examining the appropriate level of PPE are needed.

Graphical abstract

Imaging considerations for thermal and radiotherapy ablation of primary and metastatic renal cell carcinoma

Ablative (percutaneous and stereotactic) thermal and radiotherapy procedures for management of both primary and metastatic renal cell carcinoma are increasing in popularity in clinical practice. Data suggest comparable efficacy with lower cost and morbidity compared to nephrectomy. Ablative therapies may be used alone or in conjunction with surgery or chemotherapy for treatment of primary tumor and metastatic disease. Imaging plays a crucial role in pre-treatment selection and planning of ablation, intra-procedural guidance, evaluation for complications, short- and long-term post-procedural surveillance of disease, and treatment response. Treatment response and disease recurrence may differ considerably after ablation, particularly for stereotactic radiotherapy, when compared to conventional surgical and chemotherapies. This article reviews the current and emerging role of imaging for ablative therapy of renal cell carcinoma.

Microwave Ablation of Renal Cell Carcinoma

Management options for small renal masses include active surveillance, partial nephrectomy, radical nephrectomy, and thermal ablation. For tumors typically ≤3 cm in size, thermal ablation is a good option for those desiring an alternative to surgery or active surveillance, especially in patients who are considered high surgical risk. We favor microwave ablation because of the more rapid heating, higher temperatures that overcome the heat sink effect of vessels, reproducible cell kill, and a highly visible ablation zone formed by water vapor that corresponds well to the zone of necrosis. For central tumors, we favor cryoablation because of the slower formation of the ablation zone and less likelihood of damage to the collecting system. With microwaves, it is important to monitor the ablation zone in real time (ultrasound is the best modality for this purpose), avoid direct punctures of the collecting system, and to place probes tangential to the collecting system to avoid burning open a persistent tract between the urothelium and extrarenal spaces or causing strictures. The surgical steps described in this video cover our use of high-frequency jet ventilation with general anesthesia to minimize organ motion, initial imaging and targeting, probe insertion, hydrodissection (a technique that enables displacement of adjacent structures), the ablation itself, and finally our dressing. Postoperative cares typically consist of observation with a same-day discharge or an overnight stay. Follow-up includes a magnetic resonance imaging abdomen with and without contrast, chest X-ray, and laboratories (basic metabolic panel, complete blood count, and C-reactive protein) 6 months postablation. Overall, percutaneous microwave ablation is an effective and safe treatment option for renal cell carcinoma in both T1a and T1b tumors in selected patients with multiple studies showing excellent oncologic outcomes when compared with partial and radical nephrectomy.

sABLATE: a simplified ABLATE score for prediction of complications and outcome in percutaneous thermal ablation of renal lesions

The aim of the study is to evaluate the performance of a simplified ABLATE score (sABLATE) in predicting complications and outcome with respect to RENAL, mRENAL, and ABLATE scores. This study included 136 renal lesions in 113 patients (M:F ratio = 2.5; mean age 70.8 years). 98 tumors underwent cryoablation at San Raffaele hospital between 01/2015 and 03/2020, while 37 underwent microwave ablation at San Paolo or Policlinico hospitals between 07/2016 and 03/2020. RENAL, mRENAL, ABLATE, and sABLATE scores were calculated using pre-procedural imaging. Data regarding complications and follow-up were registered. Mann-Whitney U test, ROC analyses, and logistic regression analyses were used for complications. Cox-regression analyses were performed for outcome. Mean tumor diameter was 23.2 mm. Mean and median RENAL, mRENAL, ABLATE, and sABLATE scores were 6.8 and 7, 6.9 and 7, 5.3, and 5, and 3.5 and 3, respectively. During a mean follow-up of 21.9 months (range 1-73), we registered 7 complications, 3 cases of residual disease, and 10 local tumor progressions. Mann-Whitney U test p values for complications for RENAL, mRENAL, ABLATE, and sABLATE were 0.51, 0.49, 0.66, and 0.056, respectively. ROC analyses for complications showed an AUC for RENAL, mRENAL, ABLATE, and sABLATE of 0.57, 0.57, 0.55, and 0.71, respectively. Regarding outcome, HR and p values of Cox-regression analyses were 1.30 and 0.36 for RENAL, 1.33 and 0.35 for mRENAL, 2.16 and 0.01 for ABLATE, 2.29 and 0.004 for sABLATE. sABLATE was the only score close to significance for complications, representing a progress even if not definitive. Regarding outcome, ABLATE confirmed its value, and sABLATE maintained validity despite being a simplification.

Computed Tomography-Guided Percutaneous Microwave Ablation for Renal Cell Carcinoma: Impact of Tumor Size on the Progression Survival Rates

The aim of the present study was to evaluate the safety and efficacy of computed tomography (CT)-guided percutaneous microwave ablation (MWA) of renal cell carcinoma (RCC) along with identifying prognostic factors affecting the progression survival rate. Institutional database retrospective research identified 69 patients with a biopsy proven solitary T1a (82.6%) or TIb (17.4%) RCC who have underwent percutaneous CT-guided MWA. Kaplan–Meier survival estimates for events were graphed and Cox regression analysis was conducted. Mean patient age was 70.4 ± 11.5 years. Mean size of the lesions was 3 ± 1.3 cm. Mean follow up time was 35.6 months (SD = 21.1). The mean progression free survival time from last ablation was 84.2 months. For T1a tumors, the cumulative progression free survival rate for 1, 6, 12 and 36 months were 100% (SE = 0%), 91.2% (SE = 3.7%), 91.2% (SE = 3.7%) and 87.5% (SE = 4.4%); the recurrence free survival rate for T1a RCC was 94.9%. For T1b tumors, the cumulative progression free survival rate for 1, 6, 12 and 36 months were 100% (SE = 0%), 63.6% (SE = 14.5%), 63.6% (SE = 14.5%) and 63.6% (SE = 14.5%). Grade 1 complications were recorded in 5 (7.2%) patients. Significantly greater hazard for progression was found in cases with a tumor size > 4 cm (HR = 9.09, p = 0.048). No statistically important difference regarding tumor progression was recorded between T1a tumors with a diameter ≤3 cm and >3 cm. In summary, the results of the present study show that CT guided percutaneous MWA is an effective technique for treatment of T1a renal cell carcinomas, irrespective of tumor size. T1b tumors were associated with higher progression rates.

Efficacy and safety of CT-guided microwave ablation for stage T1a renal cell carcinoma in patients with a solitary kidney

OBJECTIVE

To retrospectively evaluate early clinical outcomes of percutaneous microwave ablation (MWA) for stage T1a renal cell carcinomas (RCCs) in solitary kidney patients.

MATERIALS AND METHODS

15 solitary kidney patients with 16 stage T1a N0M0 biopsy-proved RCCs underwent CT-guided percutaneous microwave ablation between October 2016 and July 2020. The patients were followed up with contrast-enhanced computed tomography or magnetic resonance imaging at 1, 3, and 6 months and every 6 months thereafter. Serum creatinine levels of each patient pre MWA, 1 day after MWA and the most recent record were collected. Technical effectiveness, local recurrence, survival rates and complications were accessed.

RESULTS

Complete ablation was achieved in all 16 tumors (100%) including 13 clear cell carcinomas and 3 papillary carcinomas. Within the follow-up time (median: 24 months) no tumor recurrence or major complication was detected. No significant change in serum creatinine level was noted. The cancer-specific survival rate was 100% (15 of 15), and 1-, 2-, and 3-year overall survival rates were 100%, 93.3%, and 93.3%, respectively.

CONCLUSION

Percutaneous MWA is an effective and safe treatment option for stage T1a RCCs in solitary kidney patients; it can achieve high complete ablation rate in selected lesions of appropriate size and location.

A multicenter 10-year oncologic outcome of ultrasound-guided percutaneous microwave ablation of clinical T1 renal cell carcinoma: will it stand the test of time?

OBJECTIVES

We updated the experience on percutaneous microwave ablation for renal cell carcinoma with five-center data and long-term follow-up.

METHODS

This retrospective study reviewed the T1N0M0 renal cell carcinoma patients who underwent microwave ablation between April 2006 and December 2019. Clinicopathological and procedural data were collected. Technical effectiveness and complications were assessed, and the Kaplan-Meier method was used for cancer-specific survival, disease-free survival, overall survival, and local neoplastic process analyses.

RESULTS

A total of 323 consecutive patients (mean age, 62.9 years ± 14.0) with 371 biopsy-proved tumors (mean diameter, 2.9 cm ± 1.2) were enrolled, and 42.6% of the tumors were located adjacent to collecting system/bowel and technical effectiveness was achieved in 360 (97.0%) tumors. For 275 cT1a patients, during median follow-up time of 66.0 months (IQR, 58.4-73.6), 10-year local neoplastic processes, cancer-specific survival, disease-free survival, and overall survival rates were 1.9%, 87.4%, 71.8, and 67.5%, respectively. For 48 cT1b patients, during the median follow-up time of 30.4 months (IQR, 17.7-44.8), 5-year local tumor progression, cancer-specific survival, disease-free survival, and overall survival rates were 11.3%, 91.4%, 69.1, and 89.2%, respectively. Major complications showed no differences between cT1a (3.5%) and cT1b (6.9%) patients (p = 0.28). A clinical risk stratification system was developed based on multivariable model to predict DFS and CSS with c-indexes of 0.78 (95% CI: 0.71-0.85) and 0.77 (95% CI: 0.65-0.90), respectively.

CONCLUSIONS

With matured follow-up at five institutions, ultrasound-guided percutaneous microwave ablation is a reliable treatment option for cT1a renal cell carcinoma even in dangerous location and appears to be promising for cT1b tumors.

KEY POINTS

• To our knowledge, this is the first multicenter cohort of long-term oncologic outcomes with percutaneous MWA of cT1 RCC. • The predicting model we developed is accurate to predict the long-term DFS and CSS, which can help to provide a better MWA prognostication over routinely available clinical information. • The available evidence shows that microwave ablation of clinical stage T1 RCC is safe and reliable with promising long-term oncologic outcomes, especially for cT1a RCC with excellent 10-year results.

Percutaneous microwave ablation of renal cell carcinoma: practice guidelines of the ultrasound committee of Chinese medical association, interventional oncology committee of Chinese research hospital association

Imaging-guided percutaneous microwave ablation (MWA) with high thermal efficiency comprises rapid, successful management of small renal cell carcinomas (RCCs) in selected patients. Ultrasound Committee of Chinese Medical Association, Interventional Oncology Committee of Chinese Research Hospital Association developed evidence-based guidelines for MWA of RCCs after systematically reviewing the 1969-2019 literature. Systematic reviews, meta-analyses, randomized controlled trials, cohort, and case-control studies reporting MWA of RCCs were included and levels of evidence assessed. Altogether, 146 articles were identified, of which 35 reported percutaneous MWA for T1a RCCs and 5 articles for T1b RCCs. Guidelines were established based on indications, techniques, safety, and effectiveness of MWA for RCCs, with the goal of standardizing imaging-guided percutaneous MWA treatment of RCCs. Key points Microwave ablation is recommended for managing small renal cell carcinoma in selected patients. Imaging protocols are tailored based on the procedural plan, guidance, and evaluation. Patient's selection evaluation, updated technique information, clinical efficacy, and complications are recommended to standardize management. A joint task force (multidisciplinary team) summarized the key elements of the standardized report.

MR-Guided Microwave Ablation in T1 Renal Cell Carcinoma: Initial Results in Clinical Routine

Objective

Percutaneous tumor ablation is usually performed using computed tomography (CT) or ultrasound (US) guidance, although reliable visualization of the target tumor could be challenging. Magnetic resonance- (MR-) guided ablation provides more reliable visualization of the target tumors and allows multiplanar imaging of the treatment process, making it the modality of choice, in particular if lesions are small.

Methods

From March 2016 to January 2018, 32 patients scheduled for percutaneous treatment of T1 RCC underwent MR-guided MWA. Complications were classified according to the Clavien grade. Kaplan–Meier survival estimates were calculated to evaluate progression-free survival (PFS).

Results

Technical success was achieved in all lesions. The mean energy and procedure duration were 61.6 ± 8.7 kJ and 118.2 ± 26.7 min, respectively. The glomerular filtration rate (GFR) dropped rapidly after 1 month of treatment and slowly recovered within three months (P < 0.05). Postoperative pain and fever were the most common adverse events after treatment. Perirenal hematoma, thermal injury of the psoas muscle, and abdominal distension were common complications after MWA, and the incidence rates were 9.4% (3/32), 6.3% (2/32), and 6.3% (2/32), respectively. According to the Clavien grade classification, serious complications include hydrothorax, bowel injury, and renal failure, all of which have a probability of 3.1%. Of note, the three serious complications occurred in one patient. The 1-, 2-, and 3-year PFS rates were 96.9%, 93.8%, and 83.9%, respectively. The mean PFS rates were 33.972 months (95% CI: 33.045, 35.900).

Conclusion

Microwave ablation is feasible under MR guidance and provides effective treatment of RCC in one session.

Combining Stereotactic Body Radiotherapy and Microwave Ablation Appears Safe and Feasible for Renal Cell Carcinoma in an Early Series

Microwave (MW) ablation and stereotactic body radiation therapy (SBRT) are both used in treating inoperable renal cell carcinoma (RCC). MW ablation and SBRT have potentially complementary advantages and limitations. Combining SBRT and MW ablation may optimize tumor control and toxicity for patients with larger (> 5 cm) RCCs or those with vascular involvement. Seven patients with RCC were treated at our institution with combination of SBRT and MW ablation, median tumor size of 6.4 cm. Local control was 100% with a median follow-up of 15 months. Four patients experienced grade 2 nausea during SBRT. Three patients experienced toxicities after MW ablation, 2 with grade 1 hematuria and 1 with grade 3 retroperitoneal bleed/collecting system injury. Median eGFR (estimated glomerular filtration rate) preceding and following SBRT and MW ablation was 69 mL/min/1.73 m² and 68 mL/min/1.73 m² (P = .19), respectively. In patients who are not surgical candidates, larger RCCs or those with vascular invasion are challenging to treat. Combination treatment with SBRT and MW ablation may balance the risks and benefits of both therapies and demonstrates high local control in our series. MW ablation and SBRT have potentially complementary advantages and limitations.

Percutaneous Microwave Ablation of Category T1a Renal Cell Carcinoma: Intermediate Results on Safety, Technical Feasibility, and Clinical Outcomes of 119 Tumors

OBJECTIVE. The purpose of this study was to assess the safety, technical results, and clinical outcomes of CT-guided percutaneous microwave ablation of category T1a renal cell carcinoma. MATERIALS AND METHODS. This retrospective study investigated consecutive patients who underwent CT-guided microwave ablation for T1a renal cell carcinoma from October 2015 to May 2019. Patient demographics including tumor characteristics, comorbidities, technical details, and clinical outcomes were evaluated. Local progression-free survival and overall survival rates were estimated using the Kaplan-Meier method. RESULTS. One hundred-six patients including 70 men (mean age, 68.5 ± 8.9 [SD] years; range, 49-86 years) and 36 women (mean age, 69.5 ± 10.0 years; range, 50-88 years) with an overall mean age of 68.8 ± 9.2 years (range, 49-88 years) with 119 T1a renal cell carcinomas were treated with CT-guided microwave ablation. Technical success was achieved for 100% of the tumors. Complete response was achieved in 101 (95.3%) patients and partial response was achieved in five (4.7%) patients. Local progression-free survival was 100.0%, 92.8%, and 90.6% at 1, 2, and 3 years, respectively. Overall survival was 99.0%, 97.7%, and 94.6% at 1, 2, and 3 years, respectively. Six patients (5.7%) had seven complications (five with Clavien-Dindo Grade I, Society of Interventional Radiology [SIR] category A, two with Clavien-Dindo Grade III, SIR category B) within 30 days of the procedure. CONCLUSION. CT-guided percutaneous microwave ablation is associated with high rates of technical success, excellent local progression-free survival and overall survival, and a low complication rate for category T1a renal cell carcinoma.

Comparison of microwave ablation treatments in patients with renal secondary and primary hyperparathyroidism

Purpose

Microwave ablation (MWA) is feasible for severe renal secondary hyperparathyroidism (SHPT) and primary hyperparathyroidism (PHPT) patients ineligible for parathyroidectomy (PTX). Here we compared the clinical manifestations and characteristics of parathyroid glands in these two groups, and summarized the techniques, safety and efficacy of MWA.

Methods

Baseline clinical characteristics, ablation-related techniques, adverse events/complications, and efficacy were recorded.

Results

In SHPT group, malnutrition, cardiovascular/pulmonary complications, and abnormal bone metabolism were severe. SHPT patients had more hyperplastic parathyroid glands. The volume of each gland was smaller, and the time of ablation for a single parathyroid was shorter in the SHPT group, although there were no significant differences compared with patients in the PHPT group. Three patients in both groups had recurrent laryngeal nerve injuries and all recovered, except for one SHPT patient. By the end of follow-up, serum iPTH levels had decreased from 2400.26 ± 844.26 pg/mL to 429.39 ± 407.93 pg/mL (p < .01) in SHPT and from 297.73 ± 295.32 pg/mL to 72.22 ± 36.51 pg/mL in PHPT group (p < .01). Hypocalcemia was more common (p < .001) and serum iPTH levels were prone to rebound in SHPT patients after MWA.

Conclusion

MWA can be reserved for those who had high surgical risks because of less invasiveness. Injuries of recurrent laryngeal nerves should be noticed. The health status, perioperative, and intraoperative procedures were more complicated and all parathyroids found by ultrasound should be ablated completely in SHPT patients.

Risk Factors of Ureteral Stenosis After Percutaneous Microwave Ablation of Renal Tumor, a Single-Center Experience

Background

Ureteral stenosis after percutaneous microwave ablation (MWA) of renal tumor is a rare but severe complication, and its risk factors are not apparent.

Purpose

This study aimed to investigate the risk factors for stenosis of ureter after MWA treatment of the renal tumor that is a rare complication.

Materials and Methods

Data of 211 patients who underwent MWA for the treatment of renal tumor were retrospectively analyzed from September 2006 to August 2019. Demographic characteristics, clinical features, ablation parameters, and outcomes were analyzed to find out the potential risk factors of this complication. P < 0.05 is considered significant.

Results

Six of 211 patients developed ureter stenosis, and the rate of this complication is 2.84%. The median time of emergence of hydronephrosis was 226 (range, 3-390) days. Univariate analysis shows the distance between ureter and tumor (P = 0.225) or ablation zone (P = 0.089) is not related to this complication. Postoperative urine routine (red blood cell, P = 0.001; white blood cell, P = 0.035) and R.E.N.A.L. score (P < 0.001) is related to this complication. But after multivariate logistic analysis, only R.E.N.A.L. score (P = 0.004) is associated with this complication. The location and growth pattern of tumor and the energy of ablation were not related to this complication independently.

Conclusion

The stenosis of the ureter after MWA of renal tumor is not associated with the tumor size, location, or the distance between the ureter and tumor and ablation site independently. But R.E.N.A.L. score is associated with ureter stenosis after MWA for the treatment of renal tumor, which combines the information of location, depth, and size of tumor. Preoperative evaluation of the tumor is necessary for avoiding ureter stenosis. Further studies should focus on these risk factors of this complication.

CT and MR imaging surveillance of stage 1 renal cell carcinoma after microwave ablation

OBJECTIVE

To describe the CT and MR imaging findings after microwave ablation of clinical stage 1 renal cell carcinoma (RCC).

METHODS

This single-center retrospective study was performed under a waiver of informed consent. 49 patients (38 M/11F, mean age 66 ± 9.0) with 52 cT1a RCC and 19 patients (10M/9F, mean age 67 ± 9.7) with 19 cT1b RCC were treated with percutaneous microwave ablation between January 2012 and June 2014. The size and volume of the RCC and ablation zone were measured and the kidney, ablation zones and retroperitoneum were assessed at immediate post-procedure CT and surveillance CT and MRI.

RESULTS

Median imaging follow-up was 18 months (IQR 12-28). Ablation zones were heterogeneously hyperintense on T1W and hypointense on T2W MRI and hyperdense at CT. Thin peripheral, but no internal enhancement after contrast administration signified successful ablation zones. Ablation zones decreased in size, but did not resolve during surveillance. Immediate post-procedure subcapsular gas and hematoma (5/71, 7%) resolved prior to first follow-up. Focal, enhancing soft tissue within the ablation zone, invariably along the renal margin, signified local recurrence. Local recurrence rates were higher for T1b (2/19, 11%) compared to T1a (1/52, 2%). Urinomas (4/71, 6%) decreased in size and resolved during surveillance. Retroperitoneal fat necrosis (6/71, 9%), with opposed-phase loss of T1W MRI signal, was confirmed at histology after percutaneous biopsy.

CONCLUSION

CT and MR imaging features after microwave ablation of renal cell carcinoma are predictable and reliably demonstrate treatment success, early and delayed complications, and local recurrences that can guide patient management.

Percutaneous Thermal Ablation for Treatment of T1a Renal Cell Carcinomas

Based on Surveillance, Epidemiology, and End Results studies, most renal cancers are low grade and slow growing. Long-term, single-center studies show excellent outcomes for T1a renal cell carcinoma (RCC), comparable to partial nephrectomy without affecting renal function and with much lower rates of complications. However, there are no multicenter randomized controlled trials of multiple ablative modalities or comparison with partial nephrectomy, and most studies are single-arm observational studies with short-term and intermediate follow-up. For treatment of stage T1a RCC, percutaneous TA is an effective alternative to surgery with preservation of renal function, low risk, and comparable overall and disease-specific survival.

Outcomes of Microwave Ablation for Small Renal Masses: A Single Center Experience

Purpose: To investigate the safety of microwave ablation (MWA) as an emerging technology for treating small renal masses. Materials and Methods: Patients with renal masses treated at a high-volume center with MWA between March 2015 and June 2019 were retrospectively identified. Safety, changes in renal function, primary treatment efficacy, and the natural history of imaging characteristics of masses postablation were examined. Results: Forty-five patients underwent MWA during the study period. Median age was 71 years (range 31-87). Median RENAL nephrometry score was 6 (range 4-9) with mean tumor size 2.6 ± 0.7 cm. Thirty-three percent of tumors were within 4 mm of the collecting system. Median total microwave energy applied was 400 W (range 105-2600 W). There was no significant change in creatinine (p = 0.21) or glomerular filtration rate (GFR) (p = 0.09) from preoperative to postoperative day 1 (POD#1) levels. There was a statistically but not clinically significant decrease in hemoglobin from preoperative to POD#1 levels (estimated -0.06 from 7 days before procedure to POD#1, p = 0.02). There was no durable change in creatinine (p = 0.16) or GFR (p = 0.72) at median follow-up of 7.5 months. There were 4 (9%) complications: three Clavien grade 1 and one Clavien grade 3 that led to loss of the kidney. Tumor size decreased postoperatively by an estimated -0.03 cm/month (range 0-1.9 cm, p < 0.01). Initial technical success was 100%. Primary treatment efficacy was 94%. Conclusion: MWA shows promise as an alternative thermal ablative technique with excellent short-term outcomes.

Computed tomography (CT)-guided percutaneous coaxial biopsy combined with microwave ablation for the treatment of renal masses

PURPOSE

This study aimed to investigate the feasibility, safety, and efficacy of computed tomography (CT)-guided percutaneous coaxial biopsy combined with microwave ablation (MWA) for the treatment of renal masses.

MATERIAL AND METHODS

The clinical data of ten patients (14 tumors) treated with CT-guided percutaneous coaxial biopsy combined with MWA from January 2017 to November 2019 were retrospectively analyzed. The patients were followed up for 2-33 months. The outcomes were evaluated with plain and contrast spiral CT scans. Renal function was assessed using the estimated glomerular filtration rate.

RESULTS

No severe MWA-related complication was observed. All the tumors were successfully ablated. There was no imaging evidence of local residual tumor, local tumor recurrence, or disease progression during the follow-up period.

CONCLUSIONS

CT-guided percutaneous coaxial biopsy combined with MWA might be an effective option for the diagnosis and treatment of renal masses in selected patients.

Exploiting Tissue Dielectric Properties to Shape Microwave Thermal Ablation Zones

The dielectric characterization of tissue targets of microwave thermal ablation (MTA) have improved the efficacy and pre-procedural planning of treatment. In some clinical scenarios, the tissue target lies at the interface with an external layer of fat. The aim of this work is to investigate the influence of the dielectric contrast between fat and target tissue on the shape and size of the ablation zone. A 2.45 GHz monopole antenna is placed parallel to an interface modelled by fat and a tissue characterized by higher dielectric properties and powered at 30 and 60 W for 60 s. The performances of MTA are numerically investigated considering different interface scenarios (i.e., different widths of fat layer, shifts in the antenna alignment) and a homogeneous reference scenario. Experiments (N = 10) are conducted on ex vivo porcine tissue to validate the numerical results. Asymmetric heating patterns are obtained in the interface scenario, the ablation zone in the target tissue is two-fold to ten-fold the size of the zone in the adipose tissue, and up to four times larger than the homogenous scenario. The adipose tissue reflects the electromagnetic energy into the adjacent tissue target, reducing the heating in the opposite direction.

Image-guided thermal ablation of central renal tumors with retrograde cold pyeloperfusion technique: a monocentric experience

Purpose: To evaluate feasibility, safety and efficacy of image-guided thermal ablations associated with retrograde pyeloperfusion in patients with centrally located renal tumors.Materials and methods: 48 patients (15 women, 33 men, mean age 69.1 ± 11.8) were treated with image-guided thermal ablation associated with pyeloperfusion for 58 centrally located renal tumors (mean diameter 32.3 ± 7.32 mm). 7 patients had a single kidney. Microwave and radiofrequency ablation were used. All treatments were performed with ultrasound, CT, or fusion imaging guidance under general anesthesia and simultaneous retrograde cold pyeloperfusion technique.Results: Procedure was feasible in all cases. Technical success and primary technical efficacy were reached in 51/58 (88%) and 45/54 tumors (83%). With a second ablation performed in 5 tumors, secondary technical efficacy was achieved in 50/50 (100%) tumors. Minor and major complications occurred in 8/58 (13%) and 5/58 (8%) tumors. No significative change in renal function occurred after treatment.During follow-up, 5 recurrences occurred, that were retreated with a second ablation. At last follow up (mean 32.2 ± 22.0 months), 41/48 (85%) treated patients were free from disease. The median TTP and PFS were 27.0 (range, 2.3-80.0) and 26.5 months (range, 2.3-80.0), respectively.Conclusion: Image-guided thermal ablation associated with protective pyeloperfusion is a feasible, safe, and effective treatment option for patients with central renal tumors with a minimal impact on renal function and relevant potential to avoid nephrectomy.

Stereotactic Ablative Radiotherapy for ≥T1b Primary Renal Cell Carcinoma: A Report From the International Radiosurgery Oncology Consortium for Kidney (IROCK)

PURPOSE

Patients with larger (T1b, >4 cm) renal cell carcinoma (RCC) not suitable for surgery have few treatment options because thermal ablation is less effective in this setting. We hypothesize that SABR represents an effective, safe, and nephron-sparing alternative for large RCC.

METHODS AND MATERIALS

Individual patient data from 9 institutions in Germany, Australia, USA, Canada, and Japan were pooled. Patients with T1a tumors, M1 disease, and/or upper tract urothelial carcinoma were excluded. Demographics, treatment, oncologic, and renal function outcomes were assessed using descriptive statistics. Kaplan-Meier estimates and univariable and multivariable Cox proportional hazards regression were generated for oncologic outcomes.

RESULTS

Ninety-five patients were included. Median follow-up was 2.7 years. Median age was 76 years, median tumor diameter was 4.9 cm, and 81.1% had Eastern Cooperative Oncology Group performance status of 0 to 1 (or Karnofsky performance status ≥70%). In patients for whom operability details were reported, 77.6% were defined as inoperable as determined by the referring urologist. Mean baseline estimated glomerular filtration rate (eGFR) was 57.2 mL/min (mild-to-moderate dysfunction), with 30% of the cohort having moderate-to-severe dysfunction (eGFR <45mL/min). After SABR, eGFR decreased by 7.9 mL/min. Three patients (3.2%) required dialysis. Thirty-eight patients (40%) had a grade 1 to 2 toxicity. No grade 3 to 5 toxicities were reported. Cancer-specific survival, overall survival, and progression-free survival were 96.1%, 83.7%, and 81.0% at 2 years and 91.4%, 69.2%, 64.9% at 4 years, respectively. Local, distant, and any failure at 4 years were 2.9%, 11.1%, and 12.1% (cumulative incidence function with death as competing event). On multivariable analysis, increasing tumor size was associated with inferior cancer-specific survival (hazard ratio per 1 cm increase: 1.30; P < .001).

CONCLUSIONS

SABR for larger RCC in this older, largely medically inoperable cohort, demonstrated efficacy and tolerability and had modest impact on renal function. SABR appears to be a viable treatment option in this patient population.

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.

Acute kidney injury after nephron sparing surgery and microwave ablation: focus on incidence, survival impact and prediction

Purpose: To compare acute kidney injury (AKI) incidence between nephron sparing surgery (NSS) and microwave ablation (MWA) for T1a RCC patients, reveal the effect of AKI on survival prognosis, construct AKI nomogram and use Law of Total Probability for survival probability (SP) prediction.Materials and methods: Patients were studied retrospectively after NSS (n = 1267) or MWA (n = 210) from January 1, 2011 to June 30, 2017. Using one to one Propensity Score Matching (PSM), 158 pairs of patients were identified for the cohort study. AKI incidence, risk factors and impact on survival outcomes were analyzed using Chi-square test, logistic and cox regression analysis. AKI risk and SP were predicted by nomogram and Law of Total Probability. The performance of the nomogram was assessed with respect to its discrimination, calibration, and clinical usefulness.Results: AKI occurred more commonly in NSS (27.85%) cohort, when compared to MWA (17.72%) cohort (p = 0.032), but treatment modality was not independently predictive of AKI occurrence (odds ratio [OR]: 0.598; 95% confidence interval [CI]: 0.282-1.265; p = 0.178). The 5-yr overall survival (OS) was lower in AKI patients (73.5%) compared with non-AKI patients (94.8%; p < 0.001). AKI was an independent risk factor for all-cause mortality in RCC patients (hazard ratio [HR]: 2.820; 95% confidence interval [CI]: 1.110-7.165; p = 0.029). Predictors for both NSS- and MWA-related AKI included tumor diameter, baseline eGFR and CCI score. RENAL score and tumor blood supply can predict AKI after NSS and MWA, respectively. The AKI normograms demonstrated good discrimination, with AUCs >0.86, excellent calibration and net benefits at the decision curve analysis with probabilities ≥5%. SP predicted by Law of Total Probability was comparable to actual OS.Conclusion: AKI was an early indicator for poor overall survival in RCC patients. It can be predicted by several oncological parameters. Nomogram and Law of Total Probability can accurately predict AKI risk and SP.

Percutaneous Microwave Ablation of Histologically Proven T1 Renal Cell Carcinoma

Objectives

To assess the safety and efficacy of percutaneous microwave ablation (MWA) of histologically proven T1 renal cell carcinoma (RCC).

Methods

We analysed patients with a histologically proven RCC (≤ 7 cm) treated by MWA from April 2012–April 2018. Primary and secondary efficacy, local tumour recurrence (LTR), morbidity and mortality were reported. Efficacy was defined as no residual tumour enhancement on follow-up imaging 1 month after the first ablation (primary efficacy) and after re-ablation(s) for residual disease (secondary efficacy). Adverse events (AE) were registered by the Clavien–Dindo classification and the common terminology criteria for AE. Univariable and multivariable logistic regression analyses were performed to investigate a relation among pre-treatment factors incomplete ablation and complications.

Results

In 100 patients, a total of 108 RCCs (85 T1a and 23 T1b) were treated by MWA. Median size was 3.2 cm (IQR 2.4–4.0). Primary efficacy was 89% (95%CI 0.81–0.94) for T1a lesions and 52% (95%CI 0.31–0.73) for T1b lesions (p < 0.001). Fifteen lesions (7 T1a) were re-ablated for residual disease by MWA in one (n = 13) and two (n = 2, both T1b) sessions resulting in secondary efficacy rates of 99% (T1a) and 95% (T1b, p = 0.352). LTR occurred in four tumours (2 T1a, 2 T1b) after 10–60 months. Six (4%) AEs grade > 3–5 were observed (2 T1a, 4 T1b, p = 0.045). Multivariable analysis showed that mR.E.N.A.L. nephrometry was independently associated with incomplete ablation (p = 0.012).

Conclusion

Microwave ablation is safe and effective for T1a and T1b RCC lesions with a significantly lower primary efficacy for T1b lesions.

Microwave ablation plus chemotherapy versus chemotherapy in advanced non-small cell lung cancer: a multicenter, randomized, controlled, phase III clinical trial

OBJECTIVES

This prospective trial was performed to verify whether microwave ablation (MWA) in combination with chemotherapy could provide superior survival benefit compared with chemotherapy alone.

MATERIALS AND METHODS

From March 1, 2015, to June 20, 2017, treatment-naïve patients with pathologically verified advanced or recurrent non-small cell lung cancer (NSCLC) were randomly assigned to MWA plus chemotherapy group or chemotherapy group. The primary endpoint was progression-free survival (PFS), while the secondary endpoints included overall survival (OS), time to local progression (TTLP), and objective response rate (ORR). The complications and adverse events were also reported.

RESULTS

A total of 293 patients were randomly assigned into the two groups. One hundred forty-eight patients with 117 stage IV tumors were included in the MWA plus chemotherapy group. One hundred forty-five patients with 113 stage IV tumors were included in the chemotherapy group. The median follow-up period was 13.1 months and 12.4 months, respectively. Median PFS was 10.3 months (95% CI 8.0-13.0) in the MWA plus chemotherapy group and 4.9 months (95% CI 4.2-5.7) in the chemotherapy group (HR = 0.44, 95% CI 0.28-0.53; p < 0.0001). Median OS was not reached in the MWA plus chemotherapy group and 12.6 months (95% CI 10.6-14.6) in the chemotherapy group (HR = 0.38, 95% CI 0.27-0.53; p < 0.0001) using Kaplan-Meier analyses with log-rank test. The median TTLP was 24.5 months, and the ORR was 32% in both groups. The adverse event rate was not significantly different in the two groups.

CONCLUSIONS

In patients with advanced NSCLC, longer PFS and OS can be achieved with the treatment of combined MWA and chemotherapy than chemotherapy alone.

KEY POINTS

• Patients treated with MWA plus chemotherapy had superior PFS and OS over those treated with chemotherapy alone. • The ORR of patients treated with MWA plus chemotherapy was similar to that of those treated with chemotherapy alone. • Complications associated with MWA were common but tolerable and manageable.

Percutaneous Microwave Ablation versus Laparoscopic Partial Nephrectomy for cT1a Renal Cell Carcinoma: A Propensity-matched Cohort Study of 1955 Patients

Background Percutaneous microwave ablation (MWA) and laparoscopic partial nephrectomy (LPN) are two modalities indicated for early-stage renal cell carcinoma (RCC) with low extent of invasion. Purpose To compare the long-term results of percutaneous MWA and LPN in the treatment of cT1a RCC. Materials and Methods This retrospective study included 1955 patients with cT1a RCC treated with percutaneous MWA or LPN between April 2006 and November 2017. Propensity score matching was used. Oncologic outcomes were analyzed by using the Fine-and-Gray competing risk models. Results A total of 185 patients underwent percutaneous MWA (mean age, 63.2 years ± 15.2 [standard deviation]) and 1770 underwent LPN (mean age, 50.9 years ± 13.2). During the follow-up (median, 40.6 months), after propensity score matching, no difference was observed between local tumor progression (3.2% vs 0.5%, P = .10), cancer-specific survival (2.2% vs 3.8%, P = .24), and distant metastases (4.3% vs 4.3%, P = .76). Patients who underwent percutaneous MWA had worse overall survival (hazard ratio, 2.4; 95% confidence interval: 1.0, 5.7; P = .049 vs LPN) and disease-free survival (82.9% vs 91.4%, P = .003). Percutaneous MWA led to smaller drop in estimated glomerular filtration rate at discharge (6.2% vs 16.4%, P < .001), smaller estimated blood loss (4.5 mL ± 1.3 vs 54.2 mL ± 69.2), lower cost ($3150 ± 2970 vs $6045 ± 1860 U.S. dollars), shorter operative time (0.5 minute ± 0.1 vs 1.8 minutes ± 0.6), and shorter postoperative hospitalization time (5.1 days ± 2.6 vs 6.9 days ± 2.8) (all P < .001 vs LPN). There were fewer cases of fever in the percutaneous MWA group (16.2% vs 73.0%, P < .001). Conclusion There were no significant differences regarding oncologic outcomes and complications between percutaneous microwave ablation and laparoscopic partial nephrectomy for patients with cT1a renal cell carcinoma. Percutaneous microwave ablation led to smaller renal function change and lower blood loss. For patients who cannot be subjected to the risks of more invasive laparoscopic partial nephrectomy, percutaneous microwave ablation could be an alternative less invasive treatment option. © RSNA, 2020 Online supplemental material is available for this article.

Phase I study of cancer lesion-targeted microwave coagulation therapy for localized prostate cancer: A pilot clinical study protocol

BACKGROUND

Whole-gland therapy for prostate cancer, which might cause more harm than no therapy (observation or active surveillance), might be a overtreatment. In order to avoid overtreatment as well as undertreatment of localize prostate cancer, novel strategy of organ-preserving therapies have been developed to achieve both cancer control and functional preservation. For the therapeutic techniques, microwave ablation would be an option for lesion-targeted focal therapy to eradicate biopsy-proven cancer lesion with its safety margin. Following our recent pilot clinical study of lesion-targeted focal cryotherapy, prospective clinical trial was designed to investigate the safety and therapeutic effects of lesion-targeted microwave therapy for localized prostate cancer.

METHODS

This is a single-center, phase I, clinical study to evaluate primarily the safety of lesion-targeted focal microwave treatment for prostate cancer. Patients with a magnetic resonance imaging (MRI)-visible, MR-ultrasound image-fusion targeted biopsy-proven clinically significant cancer will be enrolled. The target sample size is 5. Transrectal ultrasound-guided focal microwave ablation will be performed under general anesthesia. The primary endpoint is adverse events after microwave focal therapy. Secondary endpoint includes to assess both cancer control and quality of life (functional preservation).

DISCUSSION

This single-center, phase I, clinical study aims to evaluate the safety and efficacy of lesion-targeted focal microwave treatment for prostate cancer. The importance of this clinical trial is that it may establish new treatment for prostate cancer.

TRIAL REGISTRATION

This study was registered with Japan Registry of Clinical Trials (jRCTs052190026).

Systematic Review of Contemporary Evidence for the Management of T1 Renal Cell Carcinoma: What IRs Need to Know for Kidney Cancer Tumor Boards

Renal cell carcinoma is a relatively common malignancy, with 60 to 70 thousand cases a year in the United States alone. Increased utilization of cross-sectional imaging has led to an increase in the number of early renal cell cancers seen by the medical establishment. In addition, certain patient populations have an increased risk of developing kidney cancers which may mandate aggressive screening protocols. This article discusses the epidemiology of renal cell cancers; discusses the current management guidelines from multiple specialty societies; discusses some of the surgical and interventional techniques used in the treatment of such lesions; and provides a review of the literature regarding treatments of early-stage renal cell cancers.

Current opinion in urology 2017: focal therapy of small renal lesions

PURPOSE OF REVIEW

With the increasing incidence of small renal masses (SRMs), ablative technologies are becoming more commonly utilized. With any nascent treatment modality, outcomes literature needs to be constantly re-evaluated. The purpose of this review is to revisit the most updated literature regarding the safety and efficacy of ablative treatments of renal lesions.

RECENT FINDINGS

Recent literature demonstrates that small renal tumor ablation is safe and effective. Although it does not have the same oncological efficacy of surgical extirpation, local recurrence-free survival has consistently shown to be around 90%. Cryoablation and radiofrequency ablation have longer-term data demonstrating durable responses. Microwave ablation and irreversible electroporation are promising modalities with longer-term data coming. Complication rates and procedural morbidity of ablation are consistently lower than for partial nephrectomy.

SUMMARY

Image-guided focal ablation is a valuable tool in the management of SRMs. Although it does not have the same efficacy of surgical extirpation, with the ability to perform repeat procedures and salvage surgery if necessary, oncologic outcomes are comparable to those of upfront surgery. Ultimately, longer-term studies and prospective trials are needed to further elucidate these modalities.

Robotically-Assisted Sonic Therapy for Renal Ablation in a Live Porcine Model: Initial Preclinical Results

PURPOSE

To demonstrate the feasibility of Robotically Assisted Sonic Therapy (RAST)-a noninvasive and nonthermal focused ultrasound therapy based on histotripsy-for renal ablation in a live porcine model.

MATERIALS AND METHODS

RAST ablations (n = 11) were performed in 7 female swine: 3 evaluated at 1 week (acute) and 4 evaluated at 4 weeks (chronic). Treatment groups were acute bilateral (3 swine, 6 ablations with immediate computed tomography [CT] and sacrifice); chronic single kidney (3 swine, 3 ablations; CT at day 0, week 1, and week 4 after treatment, followed by sacrifice); and chronic bilateral (1 swine, 2 ablations). Treatments were performed using a prototype system (VortxRx; HistoSonics, Inc) and targeted a 2.5-cm-diameter sphere in the lower pole of each kidney, intentionally including the central collecting system.

RESULTS

Mean treatment time was 26.4 minutes. Ablations had a mean diameter of 2.4 ± 0.3 cm, volume of 8.5 ± 2.4 cm3, and sphericity index of 1.00. Median ablation volume decreased by 96.1% over 4 weeks. Histology demonstrated complete lysis with residual blood products inside the ablation zone. Temporary collecting system obstruction by thrombus was observed in 4/11 kidneys (2 acute and 2 chronic) and resolved by 1 week. There were no urinary leaks, main vessel thromboses, or adjacent organ injuries on imaging or necropsy.

CONCLUSIONS

In this normal porcine model, renal RAST demonstrated complete histologic destruction of the target renal tissue while sparing the urothelium.

Tumor location does not impact oncologic outcomes for percutaneous microwave ablation of clinical T1a renal cell carcinoma

OBJECTIVE

To evaluate the impact of anterior tumor location on oncologic efficacy, complication rates, and procedure duration for 151 consecutive biopsy-proven clinical T1a renal cell carcinoma (RCC) treated with percutaneous microwave (MW) ablation.

METHODS

This single-center retrospective study was performed under a waiver of informed consent. One hundred forty-eight consecutive patients (103 M/45 F; median age 67 years, IQR 61-73) with 151 cT1a biopsy-proven RCC (median diameter 2.4 cm, IQR 1.9-3.0) were treated with percutaneous MW ablation between March 2011 and August 2017. Patient and procedural data collected included Charlson comorbidity index (CCI), RENAL nephrometry score (NS), use of hydrodisplacement, MW antennas/generator output/time, and procedure time (PT). Data were stratified by anterior, posterior, and midline tumor location and compared with the Kruskal-Wallis or chi-squared tests. The Kaplan-Meier method was used for survival analyses.

RESULTS

Tumor size, NS, and use/volume of hydrodisplacement were similar for posterior and anterior tumors (p > 0.05). Patients with anterior tumors had a higher CCI (3 vs 4, p = 0.001). Median PT for posterior and anterior tumors was similar (100 vs 108 min, p = 0.26). Single session technical success and primary efficacy were achieved for all 151 tumors including 61 posterior and 67 anterior tumors. The 4 (3%) Clavien III-IV complications and 6 (4%) local recurrences were not associated with tumor location (p > 0.05). Three-year RFS, CSS, and OS were 95% (95% CI 0.87, 0.98), 100% (95% CI 1.0, 1.0), and 96% (95% CI 0.89, 0.98), respectively.

CONCLUSIONS

The safety and efficacy of percutaneous microwave ablation for anterior and posterior RCC are similar.

KEY POINTS

• The safety profile for percutaneous microwave ablation of anterior and posterior T1a renal cell carcinoma is equivalent. • Percutaneous microwave ablation of T1a renal cell carcinoma provides durable oncologic control regardless of tumor location. • Placement of additional microwave antennas and use of hydrodisplacement are associated with longer procedure times.

Available ablation energies to treat cT1 renal cell cancer: emerging technologies

Purpose

An increasing interest in percutaneous ablation of renal tumors has been caused by the increasing incidence of SRMs, the trend toward minimally invasive nephron-sparing treatments and the rapid development of local ablative technologies. In the era of shared decision making, patient preference for non-invasive treatments also leads to an increasing demand for image-guided ablation. Although some guidelines still reserve ablation for poor surgical candidates, indications may soon expand as evidence for the use of the two most validated local ablative techniques, cryoablation (CA) and radiofrequency ablation (RFA), is accumulating. Due to the collaboration between experts in the field in biomedical engineering, urologists, interventional radiologists and radiation oncologists, the improvements in ablation technologies have been evolving rapidly in the last decades, resulting in some new emerging types of ablations.

Methods

A literature search was conducted to identify original research articles investigating the clinical outcomes of new emerging technologies, percutaneous MWA, percutaneous IRE and SABR, in patients with primary cT1 localized renal cell cancer.

Results

Due to the collaboration between experts in the field in biomedical engineering, urologists, interventional radiologists and radiation oncologists, the improvements in ablation technologies have been evolving rapidly in the last decades. New emerging technologies such as microwave ablation (MWA), irreversible electroporation (IRE) and stereotactic ablative radiotherapy (SABR) seem to be getting ready for prime time.

Conclusion

This topical paper describes the new emerging technologies for cT1 localized renal cell cancer and investigates how they compare to CA and RFA.

Focal therapy versus robot-assisted partial nephrectomy in the management of clinical T1 renal masses: A systematic review and meta-analysis

BACKGROUND

Robot-assisted partial nephrectomy (RPN) and focal therapy (FT) have both been successfully employed in the management of small renal masses. However, despite this being the era of minimally invasive surgery, few comparative studies exist on RPN and FT. The aim of our study is to review perioperative, renal functional and oncologic outcomes of FT and RPN in cT1 renal masses.

METHODS

Literature published in Medline, EMBASE, and Cochrane Library databases up to April 22, 2018, was systematically searched. We included literature comparing outcomes of FT (radiofrequency ablation, cryoablation, microwave ablation, and irreversible electroporation) and RPN. Studies that reported only on laparoscopic partial nephrectomy or open partial nephrectomy, and review articles, editorials, letters, or cost analyses were excluded. In total, data from 1166 patients were included.

RESULTS

From 858 total articles, 7 nonrandomized, observational studies were included. Compared with RPN, FT was associated with a significantly lower decrease of estimated glomerular filtration rate (weighted mean difference [WMD] -8.06 mL/min/1.73 m; confidence interval [CI] -15.85 to -0.26; P = .04), and lower estimated blood loss (WMD -49.61 mL; CI -60.78 to -38.45; P < .001). However, patients who underwent FT had a significantly increased risk of local recurrence (risk ratio [RR] 9.89; CI 4.24-23.04; P < .001) and distant metastasis (RR 6.42; CI 1.70-24.33; P = .006). However, operative times, lengths of stay, and complication rates were revealed to be similar between FT and RPN.

CONCLUSION

RPN has a substantial advantage in preventing cancer recurrence. However, in the era of minimally invasive surgery, FT has advantages in renal function preservation and less bleeding. Long-term follow-up for survival rates and comparative analysis of microwave ablation and irreversible electroporation are needed to extend FT for patients with significant morbidities and for those who need sufficient renal function preservation with minimal bleeding.

Introduction of Microwave Ablation Into a Renal Ablation Practice: Valuable Lessons Learned

OBJECTIVE

The purpose of this study was to evaluate the early outcomes of percutaneous microwave ablation (MWA) for clinical stage T1 (cT1) renal masses when performed within a high-volume ablation practice with critical emphasis on procedural safety.

MATERIALS AND METHODS

A retrospective review of a percutaneous renal ablation registry identified 26 patients with a total of 27 cT1 renal masses treated with MWA between 2011 and 2017. Mean patient age was 63.8 years and 16 (61.5%) patients were male. Mean renal mass size ± SD was 2.3 ± 0.8 cm (range, 1.1-4.7 cm). The main outcome parameters investigated were technical success, local tumor progression, survival rates, and complications. Complications were categorized using the Clavien-Dindo classification system. Rates of local progression-free and cancer-specific survival (PFS and CSS, respectively) were estimated using the Kaplan-Meier method.

RESULTS

Technical success was 100% on contrast-enhanced CT or MRI performed immediately after renal MWA. Twenty-four patients (92%) with 25 tumors had follow-up imaging for 3 months or longer (mean, 20.6 ± 11.6 months), with no local tumor recurrences identified. Estimated 3-year local PFS and CSS were 96% and 94%, respectively. The overall complication rate was 19.2%; two patients (7.7%) experienced minor complications (grade I or II) and three patients (11.5%) experienced major bleeding or urinary-related complications (grade III or higher), including one death.

CONCLUSION

This study suggests that percutaneous MWA is a promising minimally invasive treatment option for cT1 renal masses. Nonetheless, major bleeding and urinary-related complications can occur, and further studies are needed to determine optimal patient and tumor selection for renal MWA.

Percutaneous microwave ablation for local control of metastatic renal cell carcinoma

PURPOSE

The purpose of the article is to evaluate the safety and oncologic efficacy of microwave ablation for metastatic renal cell carcinoma (mRCC).

MATERIALS AND METHODS

From September 2011 to December 2016, 33 mRCC were ablated in 18 patients using percutaneous microwave ablation. Sites of mRCC include retroperitoneum (n = 12), contralateral kidney (n = 6), liver (n = 6), lung (n = 5), adrenal gland (n = 5). Technical success, local, and distant tumor progression, and complications were assessed at immediate and follow-up imaging. The Kaplan-Meier method was used for survival analysis.

RESULTS

Technical success was achieved for 33/33 (100%) mRCC tumors. Ablation provided durable local control for 28/30 (93%) mRCC tumors in 17 patients at a median duration of clinical and imaging follow-up of 1.6 years (IQR 0.7-3.6) and 0.8 years (IQR 0.5-2.7), respectively. In-hospital and perioperative mortality was 0%. There were 5 (15%) procedure-related complications including one high-grade event (Clavien-Dindo III). Four patients have died from mRCC at a median of 1.3 years (range 0.7-5.1) following ablation. Estimated OS (95% CI number still at risk) at 1, 2, and 5 years were 86% (53-96%, 11), 75% (39-92%, 8), and 75% (39-92%, 3), respectively.

CONCLUSIONS

Microwave ablation of oligometastatic renal cell carcinoma is safe and provides durable local control in appropriately selected patients.