Percutaneous vs surgical cryoablation of the small renal mass: Is efficacy compromised?

Study Type - Therapy (systematic review) Level of Evidence 1b What's known on the subject? and What does the study add? Cryoablation of the small renal mass is one amongst many minimally invasive approaches to treatment. Cryoablation can be performed both surgically and percutaneously; direct comparison of the two approaches has proven the percutaneous approach to be cheaper, less morbid, result in shorter procedure times, and shorter hospital stays, all with equal efficacy. Our study examines the decision as well as reporting process for the selection of treatment approach to determine if patients are being unnecessarily exposed to more invasive therapeutic options. Objective: To review and analyse the cumulative literature to compare surgical and percutaneous cryoablation of small renal masses (SRMs). METHODS A MEDLINE search was performed (1966 to February 2010) of the published literature in which cryoablation was used as therapy for localized renal masses. Residual disease was defined as persistent enhancement on the first post-ablation imaging study, while recurrent disease was defined as enhancement after an initially negative postoperative imaging study, consistent with the consensus definition by the Working Group on Image-Guided Tumor Ablation. Data were collated and analysed using the two-sample Mann-Whitney test and random-effects Poisson regression, where appropriate. Results: In all, 42 studies, representing 1447 lesions treated by surgical (n= 28) or percutaneous (n= 14) cryoablation were pooled and analysed. No significant differences were detected between approaches regarding patient age (median 67 vs 66 years, P= 0.55), tumour size (median 2.6 vs 2.7 cm, P= 0.24),or duration of follow-up (median 14.9 vs 13.3 months, P= 0.40). Differences in rates of unknown pathology also failed to reach statistical significance (14 vs 21%, P= 0.76). The difference in the rate of residual tumour was not statistically different (0.033 vs 0.046, P= 0.25), nor was the rate of recurrent tumour (0.008 vs 0.009, P= 0.44). The reported rate of metastases was negligible in both groups, precluding statistical analysis. Conclusions: Cryoablation has shown acceptable short-term oncological results as a viable strategy for SRMs. Analysis of the cumulative literature to date shows that surgical and percutaneous cryoablation have similar oncological outcomes.