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

• To review and analyse the cumulative literature to compare surgical and percutaneous cryoablation of small renal masses (SRMs).

• 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.

• 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.

• 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.