Cryoablation vs radiofrequency ablation for the treatment of renal cell carcinoma: a meta-analysis of case series studies

Study Type - Therapy (systematic review). Level of Evidence 2b What's known on the subject? and What does the study add? The oncological success of partial nephrectomy in the treatment of small renal masses is well established. However, partial nephrectomy has largely supplanted the radical approach. In the last decade, laparoscopy has been adopted as the new surgical approach for the treatment of renal cell carcinoma. Laparoscopy offers the advantage of lower analgesic use, shorter hospital stay, and quicker recovery time. More recently, ablative technologies have been investigated as an alternative to laparoscopic partial nephrectomy. These techniques can often be performed percutaneously in the radiology suite, or laparoscopically without the need for hilar clamping. However, only the cryoablation and radiofrequency ablation modalities have had widespread use with several series reporting short to intermediate results. This review shows that both cryoablation and radiofrequency ablation are promising therapies in patients with small renal tumours (<4 cm), who are considered poor candidates for more involved surgery.

OBJECTIVE

• To determine the current status of the literature regarding the clinical efficacy and complication rates of cryoablation vs radiofrequency ablation in the treatment of small renal tumours.

METHODS

• A review of the literature was conducted. There was no language restriction. Studies were obtained from the following sources: MEDLINE, EMBASE and LILACS. • Inclusion criteria were (i) case series design with more than one case reported, (ii) use of cryoablation or radiofrequency ablation, (iii) patients with renal cell carcinoma and, (iv) outcome reported as clinical efficacy. • When available, we also quantified the complication rates from each included study. • Proportional meta-analysis was performed on both outcomes with a random-effects model. The 95% confidential intervals were also calculated.

RESULTS

• Thirty-one case series (20 cryoablation, 11 radiofrequency ablation) met all inclusion criteria. • The pooled proportion of clinical efficacy was 89% in cryoablation therapy from a total of 457 cases. There was a statistically significant heterogeneity between these studies showing the inconsistency of clinical and methodological aspects. • The pooled proportion of clinical efficacy was 90% in radiofrequency ablation therapy from a total of 426 cases. There was no statistically significant heterogeneity between these studies. • There was no statistically significant difference regarding complications rate between cryoablation and radiofrequency ablation.

CONCLUSIONS

• This review shows that both ablation therapies have similar efficacy and complication rates. • There is urgency for performing clinical trials with long-term data to establish which intervention is most suitable for the treatment of small renal masses.

Complications of laparoscopic and percutaneous renal cryoablation in a single tertiary referral center

BACKGROUND

Laparoscopic cryoablation (LCA) and percutaneous cryoablation (PCA) of small renal masses have gained popularity, but only limited data exist on the complication rates.

OBJECTIVES

In this study, we report on postoperative complications associated with LCA and PCA in a single tertiary center experience.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a retrospective review of electronic medical records for patients undergoing LCA or PCA between 2001 and 2008 at our institution.

INTERVENTIONS

All patients underwent LCA or PCA.

MEASUREMENTS

Demographics, radiographic variables, and complication rates were compared between the two groups. Complications were classified according to the modified Clavien system.

RESULTS AND LIMITATIONS

Of a total of 195 patients included in this study, 72 underwent LCA and 123 underwent PCA. There were no differences in demographics between the groups. We observed complications in 10 LCA procedures (13.9%) and 26 PCA procedures (21.1%) (p=0.253). The distribution of the complications differed significantly between the groups with mild complications (grades 1 and 2) more common in the PCA group (20.3% vs 5.6%, respectively; p=0.001), whereas severe events (grades 3 and 4) were more frequent in the LCA group (8.3% vs 0.8%, respectively; p=0.011). On multivariate analysis, age and body mass index were inversely associated with complications, whereas female gender, multiple tumors, and preexisting comorbidities showed a trend toward increased risk.

CONCLUSIONS

LCA and PCA, although minimally invasive, are not void of complications. Most of the complications encountered are mild; however, severe (grade 3 or 4) events may occur in up to 3.6% of patients. PCA may be associated with a higher rate of complications, although most of these are mild and transient. However, on multivariate analysis, the chosen ablative approach (laparoscopic or percutaneous) is not associated with the risk of complications.

Tumor size and endophytic growth pattern affect recurrence rates after laparoscopic renal cryoablation

OBJECTIVE

To analyze factors that may contribute to local relapse after laparoscopic cryoablation (LCA) of renal tumors. LCA has gained popularity in the treatment of small renal tumors, but local tumor control remains a concern.

METHODS

We analyzed 163 patients who underwent LCA between 2001 and 2008 either at Allegheny General Hospital or Duke University Medical Center, with at least 6 months of follow-up. Demographics, perioperative variables, tumor characteristics (size, pattern of growth, and biopsy results), and follow-up were recorded. Growth pattern was categorized as exophytic, mesophytic, or endophytic. Regression analyses were performed to evaluate risk factors for local relapse after LCA.

RESULTS

Median patient age was 66 (range, 33-90) years, with men comprising 60.1% of the cohort. Median tumor size was 2.4 cm (range, 0.5-5.0). Pathology was as follows: renal cell carcinoma in 118 (72.4%), other malignancies in 2 (1.2%), and no malignancy in 43 (26.4%) patients. A single lesion was treated in 95.1% patients and multiple tumors in 4.9%. Endophytic growth pattern was present in 22.8% patients. We observed 7 (4.3%) local recurrences over a median follow-up of 20 months (range, 6-79). Median time to recurrence was 15 months (range, 6-48). On proportional hazards regression, tumor size and endophytic growth pattern were significantly associated with local recurrence (P = .003 and .028; odds ratios [OR] = 4.1 and 11.4, respectively).

CONCLUSIONS

LCA demonstrated good tumor control over a 5-year follow-up, with an acceptable recurrence rate. Larger tumors and those with endophytic growth pattern may be at increased risk of relapse after LCA.

Minimally invasive surgery using ablative modalities for the localized renal mass

Due to a number of evolving devices and modalities to treat the small, localized renal mass, the physician and patient have the opportunity to choose an appropriate therapy from several treatment options. Minimally invasive surgery to ablate a localized renal tumor is an alternative strategy to nephron-sparing surgery for the small renal mass. Even though partial nephrectomy has been established as an optimal technique for nephron-sparing surgery, patients who have comorbidities and renal insufficiency would potentially benefit from less invasive treatment. With respect to those concerns, several articles are discussed here regarding thermal ablative therapy for the small renal mass along with oncological outcomes and complications among these modalities compared to conventional procedures. In this review, a comprehensive PubMed search was conducted. For the purposes of reviewing the current status of thermal ablative modalities for the small renal mass, only articles written in English published from 1992 to 2009 were considered. Cryoablation and radiofrequency ablation are the most utilized and potentially promising therapies that are evolving as nephron-sparing minimally invasive surgery for patients with a localized renal tumor. High-intensity focused ultrasound, a relatively new modality to treat the renal mass, needs further study. All modalities require long-term follow up with unified reporting methods in terms of patient selection, pre- and post-treatment evaluation, treatment description, and analysis of outcome.

Renal thermal ablative therapy

Energy targeting is greatly enhanced through imaging modalities, which greatly assist needle placement or energy delivery to the optimal location for maximal effectiveness. When vital structures obscure access to the renal lesion, laparoscopic mobilization of these structures with direct visualization of the tumor can increase the likelihood of ablation success and minimize complication risk. Ablative therapies are attractive because of their minimal impact on patient quality of life in addition to their morbidity and cost. Although they show promise of efficacy, they must be evaluated with long-term follow-up before they are considered the standard of oncologic care. Renal masses can be treated with a laparoscopic or percutaneous approach depending on tumor location, size, and the available technology and experience of the center.

Cryoablation for small renal masses

Advances in imaging techniques (CT and MRI) and widespread use of imaging especially ultrasound scanning have resulted in a dramatic increase in the detection of small renal masses. While open partial nephrectomy is still the reference standard for the management of these small renal masses, its associated morbidity has encouraged clinicians to exploit the advancements in minimally invasive ablative techniques. The last decade has seen the rapid development of laparoscopic partial nephrectomy and novel ablative techniques such as, radiofrequency ablation (RFA), high-intensity focused ultrasound (HIFU), and cryoablation (CA). In particular, CA for small renal masses has gained popularity as it combines nephron-sparing surgery with a minimally invasive approach. Studies with up to 5-year followup have shown an overall and cancer-specific 5-year survival of 82% and 100%, respectively. This manuscript will focus on the principles and clinical applications of cryoablation of small renal masses, with detailed review of relevant literature.

Urothelial sloughing with obstruction after laparoscopic cryoablation of small renal carcinoma in solitary kidney

Laparoscopic cryoablation is a minimally invasive treatment that is currently used to treat small renal tumors. Despite its growing use and promising outcomes, complications can occur. We report the first clinical case of urothelial sloughing with obstruction after cryoablation of a small renal tumor in a solitary kidney.