A Systematic Review of the Quality of Evidence of Ablative Therapy for Small Renal Masses

Comparative outcomes of radio frequency ablation versus partial nephrectomy for T1 renal tumors: a systematic review

Background

The role of radio frequency ablation (RFA) in small renal tumors remains controversial. This systematic review was performed to compare clinical outcomes of RFA versus partial nephrectomy (PN) for the treatment of T1 renal tumors.

Methods

A total of 11 studies including 2,397 patients were analyzed in this systematic review after searching the databases of PubMed, EMBASE and Web of Science. P value and odds ratio (OR)/hazard ratio (HR) with 95% confidence interval (CI) were used to evaluate the strength of the association.

Results

A total of six studies (2,056 patients) provided either survival curves or HR and its 95% CI, demonstrating that the majority of the patients with RFA treatment tended to exhibit a similar long-term survival rate to those with PN treatment. In addition, according to four studies, no differences were found in the overall rate of complications between the two groups. Furthermore, there were significant differences in glomerular filtration rate (GFR) change between the two methods in four studies but no differences were observed in other two.

Conclusions

Our systematic review indicated that RFA is an effective treatment option which could provide comparable oncologic outcomes to PN. Moreover, it may present obvious advantages in renal function preservation.

Retreatment after focal therapy for failure: a bridge too far?

PURPOSE OF REVIEW

To summarize the current knowledge about the evaluation of disease persistence and recurrence after focal therapy ablation (FTA) for small renal masses and to assess the outcomes and complications of related treatment options.

RECENT FINDINGS

FTA procedures continuously increased over the last 20 years, being now performed in more than one on 10 patients with T1a renal cell carcinoma. Disease recurrence seems to occur more often following radiofrequency ablation (RFA) compared with cryoablation. Evidence about the management of disease recurrence is scarce. Treatment options are similar to those available for de novo renal cell carcinomas, and include reablation, partial or radical nephrectomy and observation. Reablation is feasible, safe and can be easily done in the majority of cases. Oncological outcomes of repeated ablation, although encouraging, remain mostly uninvestigated and unreported.

SUMMARY

In case of disease persistence or recurrence after FTA, observation may be an acceptable approach, reserving repeated ablation or surgery only in those exhibiting significant tumor growth. In these patients repeated ablation with RFA is safe and noninvasive. Surgery after FTA presents technical difficulties related to perinephric scarring, especially with regards to nephron-sparing surgery. This should be taken into consideration in patients' counseling as well as in decision-making process.

High-Resolution Genomic Profiling of Disseminated Tumor Cells in Prostate Cancer

Circulating tumor cells and disseminated tumor cells (DTCs) are of great interest because they provide a minimally invasive window for assessing aspects of cancer biology, including tumor heterogeneity, a means to discover biomarkers of disease behavior, and a way to identify and prioritize therapeutic targets in the emerging era of precision oncology. However, the rarity of circulating tumor cells and DTCs poses a substantial challenge to the consistent success in analyzing their molecular features, including genomic aberrations. Herein, we describe optimized and robust methods to reproducibly detect genomic copy number alterations in samples of 2 to 40 cells after whole-genome amplification with the use of a high-resolution single-nuclear polymorphism-array platform and refined computational algorithms. We have determined the limit of detection for heterogeneity within a sample as 50% and also demonstrated success in analyzing single cells. We validated the genes in genomic regions that are frequently amplified or deleted by real-time quantitative PCR and nCounter copy number quantification. We further applied these methods to DTCs isolated from individuals with advanced prostate cancer to confirm their highly aberrant nature. We compared copy number alterations of DTCs with matched metastatic tumors isolated from the same individual to gain biological insight. These developments provide high-resolution genomic profiling of single and rare cell populations and should be applicable to a wide-range of sample sources.

Lessons learned from the comparative study between renal mass biopsy and the analysis of the surgical specimen

INTRODUCTION

The role of renal mass (RM) biopsy is currently under discussion. As a result of the progressive increase in the incidental diagnosis of RMs (which have a higher percentage of benignity and well-differentiated cancers), new approaches have emerged such as observation, especially with elderly patients or those with significant comorbidity. RM biopsy (RMB) should provide sufficient information for making this decision, but so far this has not been the case. We examine our prospective series of in-bench RMBs after surgery and compare them with the anatomy of the removed specimen.

MATERIAL AND METHODS

We obtained (prospectively, in-bench and with a 16-gauge needle) 4 biopsies of RMs operated on in our department from October 2008 to December 2009. These RMs were analyzed by 2 uropathologists and compared with the results of the specimen.

RESULTS

We analyzed 188 biopsies (47 RMs); 12.75% were "not valid". The ability of biopsy to diagnose malignancy or benignity was 100%, and the coincidence in the histological type was 95%. The success in determining the tumor grade was 100% when the cancer was low-grade and 62% when high-grade. None of the analyzed data (necrosis, size, etc.) influenced the results in a statistically significant manner.

CONCLUSION

RMB with a 16-G needle enables the differentiation between malignancy and benignity in 100% of cases, with a very similar diagnostic accuracy in the tumor type. Tumor grade is still the pending issue with renal mass biopsy.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A nanoengineered embolic agent for precise radiofrequency ablation

The purpose of the work is to investigate whether the electromagnetic properties of multi-walled carbon nanotubes (MWCNT) in the presence of radiofrequency (RF) energy is (1) safe, and (2) improves the precision of the therapeutic efficiency of the RF-ablation (RFA) procedure. An in vitro phantom was created for evaluating temperature near RF treated nanotubes. For the in vivo study, three baboons and six pigs were submitted for RFA procedure in superior/inferior kidney poles embolized with a non-adherent, lipophilic embolic agent (marsembol) with or without MWCNT. Tissue damage in the surrounding kill zone was assayed through caspase-3 activation. The in vitro results showed marked heat increase only in the region of the nanotubes. In vivo, necrosis/ischemic damage resulted from RFA therapy alone, RFA plus marsembol only. In marsembol + MWCNT condition, dramatic disruption of cell membranes and sub-cellular organelles was found whereas the nuclear membranes and basal cell membranes remained largely intact. The marsembol vaporized under RFA and tissue fluid filled the space. This caused the MWCNT to cluster within the new aqueous environment. RFA plus marsembol + MWCNT created a well-defined demarcation between healthy and apoptotic cells as evidenced by a marked reduction of caspase-3 expression. By contrast, there was a much less defined ablation zone in the absence of MWCNT. In conclusion, the combination of RFA plus marsembol + MWCNT embolization delineated the kill zone in vitro and in vivo. We demonstrate that MWCNTs remain in the ablation region thus minimizing their migration to the systemic circulation.

[Focal therapy in urology: kidney cancer]

Focal therapy has gained attention in the treatment of small renal masses (SRM). However, its use is limited due to scarce data on long-term outcomes. The availability of such data is significantly lower as compared to the relevant data on surgery outcomes. At the same time, minimally invasive surgery has seen the development of laparoscopic nephron-sparing surgery and, recently, robot-assisted surgery. Our purpose is to review the possibilities of treatment for SMR with particular attention on focal therapy. Clinical series and comprehensive reviews support safety and mid/long-term efficacy of renal cryoablation or radiofrequency ablation. Comparative studies and meta-analysis outlined oncological inferiority against partial nephrectomy in local tumor control. For smaller and more peripheral lesions, radiofrequency ablation showed best indications than cryoablation. There are significant demographic and tumor differences between patients treated by one or another approach. The correct indication for each treatment seems to be of key importance to achieve the best oncological and functional outcome. Open partial nephrectomy remains the gold standard treatment for PMR, but laparoscopic approaches have been showing similar results.

Application of the IDEAL framework to robotic urologic surgery

The IDEAL recommendations provide stage-specific guidance to address the unique challenges of surgical research. They are highly applicable to questions about the appropriate use of robotic-assisted laparoscopic surgery in urology by providing concrete guidance on how to assess its comparative effectiveness and safety.

Determination of the nonlethal margin inside the visible "ice-ball" during percutaneous cryoablation of renal tissue

OBJECTIVE

The study was designed to determine the distance between the visible "ice-ball" and the lethal temperature isotherm for normal renal tissue during cryoablation.

METHODS

The Animal Care Committee approved the study. Nine adult swine were used: three to determine the optimum tissue stain and six to test the hypotheses. They were anesthetized and the left renal artery was catheterized under fluoroscopy. Under MR guidance, the kidney was ablated and (at end of a complete ablation) the nonfrozen renal tissue (surrounding the "ice-ball") was stained via renal artery catheter. Kidneys were explanted and sent for slide preparation and examination. From each slide, we measured the maximum, minimum, and an in-between distance from the stained to the lethal tissue boundaries (margin). We examined each slide for evidence of "heat pump" effect.

RESULTS

A total of 126 measurements of the margin (visible "ice-ball"-lethal margin) were made. These measurements were obtained from 29 slides prepared from the 6 test animals. Mean width was 0.75 ± 0.44 mm (maximum 1.15 ± 0.51 mm). It was found to increase adjacent to large blood vessels. No "heat pump" effect was noted within the lethal zone. Data are limited to normal swine renal tissue.

CONCLUSIONS

Considering the effects of the "heat pump" phenomenon for normal renal tissue, the margin was measured to be 1.15 ± 0.51 mm. To approximate the efficacy of the "gold standard" (partial nephrectomy, ~98 %), a minimum margin of 3 mm is recommended (3 × SD). Given these assumptions and extrapolating for renal cancer, which reportedly is more cryoresistant with a lethal temperature of -40 °C, the recommended margin is 6 mm.