Percutaneous Cryoablation Of Renal Tumors Research Articles

Effects of percutaneous cryoablation for renal tumor on overall and split renal function.

To evaluate retrospectively the influence of percutaneous cryoablation for small renal tumors on total and affected kidney function and risk factors associated with worsening function of the affected kidney. Between April 2016 and March 2022, 27 patients who underwent cryoablation for small renal tumors at our institution participated in this study, which investigated time-dependent changes in postoperative renal function. We evaluated estimated glomerular filtration rates (eGFRs) and split renal function revealed by scintigraphy using 99m technetium-mercaptoacetyltriglycine (99mTc-MAG3) before cryoablation and at 1week, 1month, and 6months after cryoablation. Numerous variables were analyzed to assess risk factors for worsening renal function. Baseline eGFR (mean ± standard deviation) was 56.5 ± 23.7mL/min/1.73 m2 (mean ± SD; range, 20.5-112.5). Mean eGFRs at 1week, 1month, and 6months after cryoablation were 57.4 ± 24.5 (19.1-114.9), 57.1 ± 25.1 (21.5-114.9), and 53.8 ± 23.9mL/min/1.73 m2 (20.0-107.5), respectively. Changes were statistically insignificant (p = 1.0000, = 0.6749, and = 0.0761, respectively). Regarding split renal function, mean baseline contribution of the affected kidney determined by 99mTc-MAG3 was 49.7% ± 6.0% (38.8-63.3%); these rates at 1week, 1month, and 6months after cryoablation were 43.7% ± 8.8 (29.1-70.6%), 46.2% ± 7.7% (32.6-70.3%), and 46.0% ± 8.5% (32.5-67.6%), respectively. Differences from baseline were significant for all periods (p < 0001, < 0001, = 0.0001, respectively). Serum C reactive protein and lactate dehydrogenase at 1day following cryoablation, tumor's nearness to the collecting system or sinus, and volume of ablated normal renal parenchyma were significantly correlated with decreased contributions of the affected kidney by > 10% after cryoablation. Unlike total renal function, affected kidney function could worsen after cryoablation.

Usefulness of renal nephrometry scoring systems in the prediction of complications associated to percutaneous image-guided treatment for small renal masses

IntroductionDue to their increasing prevalence and complex management, renal tumors are challenging for health professionals. The study aims to evaluate the usefulness of R.E.N.A.L. and PADUA nephrometry scores in the prediction of complications after percutaneous cryoablation. Material and methodsThe study prospectively analyzed 90 patients with 101 stage T1a renal cell carcinoma (RCC) tumors treated with cryoablation. ResultsNinety patients with 101 small renal tumors who received cryoablative therapy were investigated. The mean age of the patients was 68 years and 74.4% were male. Most tumors were smaller than 4 cm (89.1%) and the mean PADUA and R.E.N.A.L. scores were 8.65 and 7.35, respectively. Complications were observed in 12 cases. PADUA and R.E.N.A.L. scores demonstrated moderate predictive power (AUC = 0.58 and AUC = 0.63, respectively) for post-cryoablation complications. ConclusionsPercutaneous cryoablation is a safe and effective treatment for small renal tumors. The R.E.N.A.L. and PADUA renal nephrometry scores have moderate predictive power for complications associated with percutaneous cryoablation of renal tumors.

Impacto de los sistemas de nefrometría renal en la valoración de las complicaciones en el tratamiento percutáneo guiado por imagen de las masas renales de pequeño tamaño

IntroductionDue to their increasing prevalence and complex management, renal tumors are challenging for health professionals. The study aims to evaluate the usefulness of R.E.N.A.L. and PADUA nephrometry scores in the prediction of complications after percutaneous cryoablation. Material and methodsThe study prospectively analyzed 90 patients with 101 stage T1a renal cell carcinoma (RCC) tumors treated with cryoablation. ResultsNinety patients with 101 small renal tumors who received cryoablative therapy were investigated. The mean age of the patients was 68 years and 74.4% were male. Most tumors were smaller than 4 cm (89.1%) and the mean PADUA and R.E.N.A.L. scores were 8.65 and 7.35, respectively. Complications were observed in 12 cases. PADUA and R.E.N.A.L. scores demonstrated moderate predictive power (AUC = 0.58 and AUC = 0.63, respectively) for post-cryoablation complications. ConclusionsPercutaneous cryoablation is a safe and effective treatment for small renal tumors. The R.E.N.A.L. and PADUA renal nephrometry scores have moderate predictive power for complications associated with percutaneous cryoablation of renal tumors.

Role of MRI at 1- and 3-Month Follow-up in Predicting the Likelihood of Tumor Recurrence Following Percutaneous Cryoablation of Renal Tumors.

To evaluate whether ablation volume difference relatively to tumoral volume, minimal distance between ablation area and necrotic tumor, or apparent diffusion coefficient (ADC) within the ablation area, measured on 1- and 3-month follow-up MRI following cryoablation of renal tumors, are associated with tumor recurrence. 136 renal tumors were retrospectively identified. Patients, tumor characteristics and follow-up MRI (1-, 3-, 6-month, and thereafter annually) were collected. Uni- and multivariate analyses were performed to assess the association between the investigated parameters and tumor recurrence. Over the follow-up period (27.7 ± 21.9months), 13 recurrences were identified at 20.5 ± 19.4months. At 1- and 3-month, the mean volume difference between the ablation zone and the tumor volume were + 577.5 ± 511.3% vs + 251.4 ± 209.8% (p = 0.003), and + 268.8 ± 291.1% vs + 103.8 ± 94.6% (p = 0.023) in patients without and with tumorrecurrence, respectively. At 1- and 3-month, the minimum distance between the necrotic tumor and the edge of the ablation area was 3.4 ± 2.5 vs 1.8 ± 1.9mm (p = 0.019), and 2.4 ± 2.3 vs 1.4 ± 1.8mm (p = 0.13) in patients without and with tumorrecurrence, respectively. Analysis of ADC values was not associated with tumor recurrence. After performing the multivariate analysis, only volume difference of the ablation area compared to tumor volume was associated with absence of tumor recurrence at 1- (OR = 14.1; p = 0.001) and 3-month (OR = 8.2; p = 0.01). Evaluation of volume difference between the ablation area and tumor volume on early (≤ 3months) MRI follow-up identifies patients at risk of tumor recurrence.

Complications of Percutaneous Cryoablation for Renal Tumors and Methods for Avoiding Them.

Percutaneous cryoablation of renal tumors is widely used because of its high efficacy and safety. This high safety can be attributed, at least in part, to the visibility of the ablated area as an "ice ball". This therapy has fewer complications (incidence, 0-7.2%) and is less invasive than surgery. Minor bleeding is inevitable in most kidney-related procedures, and indeed the most common complication of this therapy is bleeding (hematoma and hematuria). However, patients require treatment such as transfusion or transarterial embolization in only 0-4% of bleeding cases. Various other complications such as ureteral or collecting system injury, bowel injury, nerve injury, skin injury, infection, pneumothorax, and tract seeding also occur, but they are usually minor and asymptomatic. However, operators should know and avoid the various complications associated with this therapy. This study aimed to summarize the complications of percutaneous cryoablation for renal tumors and provide some techniques for achieving safe procedures.

Intraoperative MRI-derived volumetric ablation margins and initial correlation with local outcome after MRI-guided cryoablation of renal tumors

PurposeTo assess volumetric ablation margins derived from intraoperative pre- and post-ablation MRI after magnetic resonance imaging (MRI)-guided percutaneous cryoablation of renal tumors and explore its correlation with local treatment success.MethodsRetrospective analysis was performed on 30 patients (mean age 69y) who underwent percutaneous MRI-guided cryoablation between May 2014 and May 2020 for 32 renal tumors (size: 1.6–5.1 cm). Tumor and ice-ball volumes were segmented on intraprocedural pre- and post-ablation MR images using Software Assistant for Interventional Radiology (SAFIR) software. After MRI-MRI co-registration, the software automatically quantified the minimal treatment margin (MTM),defined as the smallest 3D distance between the tumor and ice-ball surface. Local tumor progression (LTP) after cryoablation was assessed on follow-up imaging.ResultsMedian follow-up was 16 months (range: 1–58). Local control after cryoablation was achieved in 26 cases (81%) while LTP occurred in 6 (19%). The intended MTM of ≥5 mm was achieved in 3/32 (9%) cases. Median MTM was significantly smaller for cases with (− 7 mm; IQR:-10 to − 5) vs. without LTP (3 mm; IQR:2 to 4) (P < .001). All cases of LTP had a negative MTM. All negative treatment margins occurred in tumors > 3 cm.ConclusionsDetermination of volumetric ablation margins from intraoperative MRI was feasible and may be useful in predicting local outcome after MRI-guided renal cryoablation. In our preliminary data, an intraoperative MRI-derived minimal margin extending at least 1 mm beyond the MRI-visible tumor led to local control and this was more difficult to achieve in tumors > 3 cm. Ultimately, online margin analysis may be a valuable tool to intraoperatively assess therapy success, but larger prospective studies are needed to establish a reliable threshold for clinical use.

Feasibility of Computed Tomography-guided Percutaneous Renal Cryoablation Under Local Anesthesia: A Single Center Experience in Taiwan.

To survey the safety and efficacy of percutaneous cryoablation for renal tumors under local anesthesia and pain control by using the -40°C lethal isotherm of the ice ball to cover the tumor margin as well as the coaxial cryoablation technique. All procedures were performed between February 2014 and November 2021 with computed tomography (CT) guidance. All tumors were ablated by following the aforementioned plan, according to which tumor margins were covered by the -40°C lethal isotherm. Hydrodissection and coaxial cryoablation were performed in some cases to avoid organ injury and massive bleeding. 2% xylocaine was used for local anesthesia and 50 mg of pethidine (meperidine) was injected intramuscularly for pain control and sedation. The complications were evaluated and the Kaplan-Meier method was used to estimate local recurrence-free survival (LRFS). Sixty-five tumors [49 renal cell carcinomas (RCC) and 16 angiomyolipomas] were ablated in 55 patients (median Charlson Comorbidity Index=5.0). Local recurrence occurred in three of the 49 RCC cases. Two received a second cryoablation. LRFS at three and five years were both 91%. LRFS at three and five years reached 100% in tumors <3 cm. A large tumor (≥3 cm) was observed in the recurrence group. Hemorrhage was the most common complication (76.9%). Two patients who needed blood transfusion did not receive coaxial cryoablation. Three (4.6%) major complications (Clavien-Dindo grade ≥3) occurred. By using -40°C as the pre-plan tumor coverage, with the aid of coaxial cryoablation and multiplanar reconstruction method, CT-guided percutaneous renal cryoablation under local anesthesia is a safe and effective procedure in patients with many comorbidities.

Percutaneous Cryoablation of Renal Tumors: Initial Indian Experience

Abstract Purpose The purpose of this study was to report short-term outcomes of cryoablation of early-stage renal tumors (T1a and T1b) at a tertiary hospital in India. Methods This was a retrospective study of consecutive patients who underwent cryoablation for renal cell carcinoma (RCC) from November 2018 to June 2020. Cryoablation was performed under combined ultrasound and computed tomography guidance using a helium-argon cryoablation system. Tumor number, size, location, nephrometry score, relationship of the tumor with pelvicalyceal system, and adjacent organs were tabulated, and technical and clinical success evaluated. Early and late recurrence and complications were also assessed. Results Eleven patients (median age: 62 years) with 11 tumors underwent cryoablation. The mean tumor size was 2.58 cm (range: 1.62–5.62 cm) with 10 lesions being T1a and one lesion T1b. Tissue sampling was done in 9/11 patients, 3 were papillary RCC and the rest, clear cell RCC. In two patients, the tumor was completely endophytic, three patients had partially endophytic tumors while 6 patients had exophytic lesions. The median nephrometry score was 6 (range: 4–11, Mode 4). Technical success was achieved in all patients. Complete response was achieved in 81% (9/11) of the patients at 1-month follow-up. Median follow-up period was 6 months. Two patients showed residual disease on follow-up imaging at 1 and 3 months, respectively. Conclusion Cryoablation is a promising, relatively new minimally invasive therapy for treating small renal tumors in India. It is safe, technically feasible, and shows excellent short-term efficacy.

Validation of a Web-Based Planning Tool for Percutaneous Cryoablation of Renal Tumors

PurposeTo validate a simulation environment for virtual planning of percutaneous cryoablation of renal tumors.Materials and MethodsProspectively collected data from 19 MR-guided procedures were used for validation of the simulation model. Volumetric overlap of the simulated ablation zone volume (Σ) and the segmented ablation zone volume (S; assessed on 1-month follow-up scan) was quantified. Validation metrics were DICE Similarity Coefficient (DSC; the ratio between twice the overlapping volume of both ablation zones divided by the sum of both ablation zone volumes), target overlap (the ratio between the overlapping volume of both ablation zones to the volume of S; low ratio means S is underestimated), and positive predictive value (the ratio between the overlapping volume of both ablation zones to the volume of Σ; low ratio means S is overestimated). Values were between 0 (no alignment) and 1 (perfect alignment), a value > 0.7 is considered good.ResultsMean volumes of S and Σ were 14.8 cm3 (± 9.9) and 26.7 cm3 (± 15.0), respectively. Mean DSC value was 0.63 (± 0.2), and ≥ 0.7 in 9 cases (47%). Mean target overlap and positive predictive value were 0.88 (± 0.11) and 0.53 (± 0.24), respectively. In 17 cases (89%), target overlap was ≥ 0.7; positive predictive value was ≥ 0.7 in 4 cases (21%) and < 0.6 in 13 cases (68%). This indicates S is overestimated in the majority of cases.ConclusionThe validation results showed a tendency of the simulation model to overestimate the ablation effect. Model adjustments are necessary to make it suitable for clinical use.

Editorial Comment on:“Ten-Year Experience with Percutaneous Cryoablation of Renal Tumors: Tumor Size Predicts Disease Progression” by Pickersgill et al.

<i>Editorial Comment on:</i>“Ten-Year Experience with Percutaneous Cryoablation of Renal Tumors: Tumor Size Predicts Disease Progression” by Pickersgill et al.

Ten-Year Experience with Percutaneous Cryoablation of Renal Tumors: Tumor Size Predicts Disease Progression.

Introduction: Percutaneous cryoablation (PCA) has emerged as an alternative to extirpative management of small renal masses (SRMs) in select patients, with a reduced risk of perioperative complications. Although disease recurrence is thought to occur in the early postoperative period, limited data on long-term oncologic outcomes have been published. We reviewed our 10-year experience with PCA for SRMs and assessed predictors of disease progression. Materials and Methods: We reviewed our prospectively maintained database of patients who underwent renal PCA from March 2005 to December 2015 (n = 308). Baseline patient and tumor variables were recorded, and postoperative cross-sectional imaging was examined for evidence of disease recurrence. Disease progression was defined as the presence of local recurrence or new lymphadenopathy/metastasis. Results: Mean patient age was 67.2 ± 11 years, mean tumor size was 2.7 ± 1.3 cm, and mean nephrometry score was 6.8 ± 1.7. At mean follow-up of 38 months, local recurrence and new lymphadenopathy/metastasis occurred in 10.1% (31/308) and 6.2% (19/308) of patients, respectively. Excluding patients with a solitary kidney and/or von Hippel-Lindau, local recurrence and new lymphadenopathy/metastasis occurred in 8.6% (23/268) and 1.9% (5/268) of cases, respectively. Kaplan-Meier estimated disease-free survival was 92.5% at 1 year, 89.3% at 2 years, and 86.7% at 3 years post-PCA. Increasing tumor size was a significant predictor of disease progression (hazard ratio 1.32 per 1-cm increase in size, p = 0.001). Conclusions: PCA is a viable treatment option for patients with SRMs. Increasing tumor size is a significant predictor of disease progression following PCA.

Percutaneous Cryoablation of Renal Tumors: Is It Time for a New Paradigm Shift?

PurposeTo retrospectively assess long-term outcomes of percutaneous renal cryoablation, including factors affecting complications and local recurrence rates. Materials and MethodsA total of 357 computed tomographic (CT) fluoroscopy–guided percutaneous cryoablation procedures were performed for 382 masses in 302 outpatients; 347 were biopsy-proven renal-cell carcinoma (RCC) or Bosniak category > III masses (n = 28). Benign pathologic conditions (n = 18) or metastatic non-RCC disease (n = 17) were included to analyze procedural complication rate, but recurrence rates, tumor staging, and nephrometry score were limited to RCCs. The average tumor diameter was 2.9 cm (range, 1–10.3 cm), and median nephrometry score for RCC was 8 (mean, 7.4). Protection of adjacent vital structures was performed in 34% of procedures (n = 121), and ureteral stent placement was performed for 9.2% (n = 33). All major complications were graded per surgical Clavien–Dindo criteria. ResultsThe average CT-visible cryoablation zone diameter was 5 cm (range, 2.5–10.5 cm). Grade ≥ 3 complications occurred in 2.8% of procedures (n = 10), and appeared related to only high nephrometry scores (P = .0086) and larger tumors (P = .0034). No significant changes in renal function before and after the procedure were noted (P = .18). At a mean follow-up of 31.8 months, the local tumor recurrence rate was 3.2% (11 of 347) for RCC, and no significant difference was noted between tumors larger or smaller than 3 cm (P = .15). The difference reached significance only among the small number of stage ≥ T2 RCC tumors (P = .0039). ConclusionsLong-term follow-up of percutaneous renal cryoablation demonstrates low recurrence rates with preserved renal function, even for patients with high nephrometry scores and body mass index, assuming thorough cytotoxic technique and protection measures.

Abstract No. 461 - Prophylactic arterial embolization of renal tumors to reduce hemorrhagic complications following cryoablation

The incidence of hemorrhagic complications following percutaneous cryoablation of renal tumors is non-trivial, occurring in up to 4% of cases. Patients with tumors exceeding 5 cm are at greatest risk for bleeding, and in our practice we routinely embolize large tumors prior to ablation in order to mitigate this risk. Recently, some authors have disputed the utility of pre-embolization in this setting, although data on this subject are sparse. To that end, we aimed to determine the effect of prophylactic tumor embolization on hemorrhagic complications following renal cryoablation. In this single-institution retrospective study, 837 patients underwent renal cryoablation from 2003-2016. A total of 45 patients treated with pre-embolization were identified and matched 1:1 on the basis of primary tumor size to patients who were not pre-embolized. Clinically significant (CTCAE grade 3 + ) hemorrhagic complications were identified through a review of the electronic medical record and relevant imaging. Conditional logistic regression was used to test for a difference in the complication rates while controlling for the matched pair design. 45 pre-embolized patients (mean age 72 ± 12 years; 71% male) were matched to 45 non-embolized controls (71 ± 13 years, 80% male). Mean tumor size was 5.2 ± 1.7 cm (range: 1.7-9.7 cm). Overall, 71% of pairs were matched identically on the basis of tumor size, with 95% matched within 5 mm; the largest difference in size was 9 mm. Three hemorrhagic complications (6.7%) occurred in the pre-embolization group and six (13.3%) in the control group. The odds ratios for developing a hemorrhagic complication were 60% lower in the pre-embolization group; however, the effect was not statistically significant in this sample (OR = 0.40; 95% CI: 0.08–2.06; p = 0.27). While the OR did not reach statistical significance in this sample due to limited power, the magnitude of the effect warrants further investigation given the potential clinical significance of any reduction in hemorrhagic complications. A prospective study, which would benefit from randomization to balance the sample and account for putative confounding variables, is supported by these data.

Cryotherapy of Renal Lesions: Enhancement on Contrast-Enhanced Sonography on Postoperative Day 1 Does Not Imply Viable Tissue Persistence.

To investigate whether persistent enhancement detected on contrast-enhanced sonography at postoperative day 1 (early contrast-enhanced sonography) after cryoablation of renal tumors implies the presence of residual viable tumor tissue, defined as residual enhancing tissue on reference imaging (computed tomography or magnetic resonance imaging) performed 6 months after the procedure. Seventy-four patients with percutaneous cryoablation of renal tumors had early contrast-enhanced sonography from November 2011 to August 2015. Two independent readers evaluated early contrast-enhanced sonographic findings and contrast-enhanced sonographic investigations performed 1 month after cryoablation of lesions that displayed enhancement on early contrast-enhanced sonography. They scored intralesional enhancement in 4 groups: no enhancement, few intralesional vessels, focal enhancing areas, and diffuse enhancement. Inter-reader agreement in evaluating lesion vascularity on early contrast-enhanced sonography was assessed with weighted κ statistics. Computed tomography or magnetic resonance imaging performed 6 months after the treatment was the reference procedure for assessing the absence or presence of residual disease. Inter-reader agreement in assessing intratumoral vascularization on early contrast-enhanced sonography was very good (κ = 0.90). Enhancement was absent for both readers in 33 of 74 cases; only a few intralesional vessels were visible in 21; whereas diffuse or focal enhancement was present in 13. In the remaining 7 patients, there were differences. Four lesions with focal enhancement on early contrast-enhanced sonography and 1 that was considered avascular had residual tumors on reference imaging. Ablation was successful in the remaining 69 of 74 patients (93%). After cryoablation, intratumoral enhancement on early contrast-enhanced sonography does not imply tumor cell viability.

Hemorrhagic Complications of Percutaneous Cryoablation for Renal Tumors: Results from a 7-year Prospective Study.

Cryoablation of renal tumors is assumed to have a higher risk of hemorrhagic complications compared to other ablative modalities. Our purpose was to establish the exact risk and to identify hemorrhagic risk factors. This IRB approved, 7-year prospective study included 261 renal cryoablations. Procedures were under conscious sedation and CT guidance. Pre- and postablation CT was obtained, and hemorrhagic complications were CTCAE tabulated. Age, gender, tumor size, histology, and probes number were tested based on averages or proportions using their exact permutation distribution. "High-risk" subgroups (those exceeding the thresholds of all variables) were tested for each variable alone, and for all combinations of variable threshold values. We compared the subgroup with the best PPV using one variable, with the subgroup with the best PPV using all variables (McNemmar test). The hemorrhagic complication rate was 3.5%. Four patients required transfusions, two required emergent angiograms, one required both a transfusion and angiogram, and two required bladder irrigation for outlet obstruction. Perirenal space hemorrhage was more clinically significant than elsewhere. Univariate risks were tumor size >2cm, number of probes >2, and malignant histology (P=0.005, 0.002, and 0.033, respectively). Multivariate analysis showed that patients >55years with malignant tumors >2cm requiring 2 or more probes yielded the highest PPV (7.5%). Although older patients (>55years old) with larger (>2cm), malignant tumors have an increased risk of hemorrhagic complications, the low PPV does not support the routine use of embolization. Percutaneous cryoablation has a 3.5% risk of significant hemorrhage, similar to that reported for other types of renal ablative modalities.

38 - Repeated percutaneous cryoablation for renal tumors in a solitary kidney. Case reports

38 - Repeated percutaneous cryoablation for renal tumors in a solitary kidney. Case reports

4:03 PMAbstract No. 66 - Hemorrhagic complications during percutaneous cryoablation of renal tumors: results from a 7-year prospective study

4:03 PMAbstract No. 66 - Hemorrhagic complications during percutaneous cryoablation of renal tumors: results from a 7-year prospective study

Radiation dose during CT-guided percutaneous cryoablation of renal tumors: Effect of a dose reduction protocol

PurposeTo estimate and compare the radiation dose using a standard protocol and that of a dose reduction protocol in patients undergoing CT-guided percutaneous cryoablation of renal tumors. Materials and methodsAn IRB-approved, HIPAA-compliant retrospective study of 97 CT-guided cryoablation procedures to treat a solitary renal tumor in each of 97 patients (64M, 33F; range 31–84 yrs) was performed. Fifty patients were treated using a standard dose protocol (kVp=120, mean mAs=180, monitoring scans every 3min during freezes), and an additional 47 patients were treated using a dose reduction protocol (kVp=100, mean mAs=100, monitoring scans less frequently than every 3min during freezes). Multiple Wilcoxon Mann-Whitney (rank-sum) tests were used to compare dose-length product (DLP) between the two groups. Fisher’s exact test was used to compare technique effectiveness at 12 months post ablation between the two groups. ResultsMedian DLP for the standard protocol group was 4833.5 mGy*cm (range, 1667–8267 mGy*cm); median DLP for the dose reduction group was 2648 mGy*cm (range, 850–7169 mGy*cm), significantly less than that of the standard protocol group (p<0.01). The technique effectiveness for the dose reduction group was not significantly different from that of the standard protocol group at 12 month follow up (p=0.434). ConclusionThe radiation dose during percutaneous CT-guided cryoablation of renal tumors was substantial in both the standard and the dose reduction groups; however, it was significantly lower with the protocol change that reduced dose parameters and decreased the number of CT scans.

Incidence of Hypercoagulable Events after Image-Guided Percutaneous Cryoablation of Renal Tumors: A Single-Center Experience

PurposeTo identify retrospectively hypercoagulable events that occurred over time in patients who underwent image-guided percutaneous renal cryoablation and compare the incidence with a cohort of patients who underwent surgical partial nephrectomy (PN) during the same time period. Materials and MethodsAn electronic medical record database was queried for patients who underwent percutaneous image-guided renal mass cryoablation or PN between September 2006 and June 2012. Records were examined for thrombotic events during the year following the procedure in each group. Incidence rates, Kaplan-Meier estimates, and patient demographic variables were compared using the stratified log-rank test and t test for independent samples. ResultsThe study comprised 114 cryoablation cases. The cumulative incidence of thrombotic events after 1 year was 4.39%. The incidence per 100 person-years was 4.84. There were 105 PN cases. The cumulative incidence of thrombotic events after 1 year was 1.0%. The incidence per 100 person-years was 1.14. The person-time incidence rate difference for these two groups did not reach statistical significance (P = .0894). ConclusionsThe incidence of thrombotic events in patients who underwent percutaneous renal cryoablation in this study was not significantly different than a comparable cohort who underwent surgical PN during the same time period.

Reply

We thank the author for his kind and insightful comments and for highlighting the key literature comparing cryoablation with partial nephrectomy of small renal masses. As previously stated, a recent meta-analysis found that the oncologic outcomes for cryoablation are significantly worse than partial nephrectomy, a finding that was consistent in our study. 1 Klatte T. Shariat S.F. Remzi M. Systematic Review and meta-analysis of perioperative and oncologic outcomes of laparoscopic cryoablation versus laparoscopic partial nephrectomy for the treatment of small renal tumors. J Urol. 2013; Google Scholar We recognize that, as our experience with ablative techniques increases, this gap in oncologic control may narrow as highlighted by the UK study. 2 Breen D.J. Bryant T.J. Appas A. et al. Percutaneous cryoablation of renal tumours: outcomes from 171 tumours in 147 patients. BJU Int. 2013; 112: 758-765 Crossref PubMed Scopus (85) Google Scholar The author correctly points out that we have not performed laparoscopic cryoablation since 2009, instead preferring a percutaneous approach particularly because it does not require a general anesthetic and is less invasive. We have not yet performed percutaneous cryoablation as an outpatient procedure but appreciate that, in an era that emphasizes efficiency and cost savings, this is another potential advantage of a percutaneous approach. Editorial CommentUrologyVol. 83Issue 5PreviewSmall renal masses <4 cm in patients with significant medical comorbidities remain a management dilemma for urologic surgeons. Although surgical extirpation remains the gold standard for management of renal cell carcinoma, cryoablative technology may be a reasonable alternative for poor surgical candidates. The present study reports the outcomes of 263 patients who underwent either laparoscopic (LCA) or percutaneous cryoablation (PCA) of T1a renal tumors. Both approaches of tumor ablation were well tolerated with minimal morbidity. Full-Text PDF