Percutaneous Microwave Ablation Versus Cryoablation in the Treatment of T1a Renal Tumors

Purpose: Radiofrequency and cryoablation (Cryo) are the most widely used techniques for the treatment of T1a renal tumors in non-surgical candidates, yet microwave ablation (MWA) has been gaining popularity. In this study, we tested the hypothesis that MWA has comparable safety and efficacy to Cryo in the treatment of selected T1a renal masses. Materials and Methods: A retrospective comparative analysis of two patient cohorts was carried out on 83 nodules in 72 consecutive patients treated using image-guided percutaneous ablation with either Cryo or MWA. Patient demographics, tumor histology and characteristics, technical success, procedure time, adverse events and complications, nephrometry score (mRENAL) and renal function were evaluated. Local recurrence was evaluated at 1, 6, 12 and 18–24 months. Results: Fifty-one nodules were treated with Cryo and 32 with MWA (44 and 28 patients, respectively). No statistical differences were observed following Cryo or MWA in median tumor size (p = 0.6), mRENAL (p = 0.1) or technical success (p = 0.8). Median procedure time was significantly lower using microwave ablation (p = 0.003). Median follow-up time was similar in the two groups (22 and 20 months, respectively). Occurrence of complications did not differ (Cryo 5/51, MWA 2/32; p = 0.57), and probability of complications or technical success adjusted for mRENAL did not reach statistical significance (p = 0.6). Renal function was preserved in all patients regardless of techniques. Disease recurrence was observed in 3/47 and in 1/30 treated nodules in the Cryo and MWA groups, respectively, without reaching statistical significance (p = 0.06). Conclusion: In the patient population studied, MWA showed comparable safety and efficacy relative to Cryo. Level of Evidence: Level 3, Non-randomized cohort study.