Evaluation of local control after percutaneous microwave ablation versus partial nephrectomy: A propensity score matched study.

Introduction: The incidence of small renal tumors (≤4cm) is on the rise. The gold standard treatment is partial nephrectomy (PN) but focal therapy can be a good alternative. We evaluated oncological control after treatment of T1a renal tumors by microwave ablation (MWA) compared to PN.

Methods: This is a retrospective, single-center study of all patients treated for TNM stage T1a renal tumors by either PN or MWA between 2010 and 2020. A propensity score was calculated and patients were matched 2:1 to compare recurrence-free survival, metastasis-free survival and overall survival between groups. We also compared postoperative complications using the Clavien-Dindo classification.

Results: After matching and propensity score, the two groups (41 MWA and 82 PN) were comparable. The median follow-up was 23 months (interquartiles, 9-48 months). Recurrence-free survival was higher in the PN group compared to MWA, with a recurrence rate of 17.1% in the MWA group vs 4.9% in the PN group (P=0.003). MWA treatment was a risk factor for tumor recurrence (P=0.002), but there was no significant difference in terms of metastasis-free survival (P=0.549) or overall survival (P=0.539). MWA was associated with fewer postoperative complications (P=0.0005).

Conclusion: This study shows that MWA was associated with higher risk of recurrence but similar metastasis-free survival and overall survival compared to PN. Recurrence was treated with new MWA or active surveillance. MWA may be an interesting alternative to PN for small renal tumors.

Level of evidence: Grade C.