Ablation and Surgery Show Comparable Long-term Outcomes for T1a Renal Cell Carcinoma: A Danish Nationwide Registry...

Background Incidental diagnosis of small renal masses is placing increasing pressure on health care systems. While surgical resection remains standard, ablation has emerged as a less invasive alternative, potentially reducing complications, hospital stays, and costs. However, knowledge about outcomes following ablation remains limited. Purpose To compare the long-term outcomes of ablation, surgical resection, and nephrectomy in patients with T1a renal cell carcinoma (RCC). Materials and Methods This retrospective nationwide-registry cohort study included Danish adults diagnosed with T1a RCC between January 2013 and December 2021. Patients were treated with tumor ablation, surgical resection, or nephrectomy. The primary outcome was progression, defined as distant metastasis or local recurrence. Secondary outcomes included hospital length of stay and 30-day posttreatment hospital contacts, excluding routine scheduled follow-up visits. Progression was analyzed using competing risk regression, and hazard ratios with P values are reported. The χ² test and Wilcoxon rank sum test were used for other group comparisons. Results A total of 1862 patients (median age, 64 years [IQR, 55-71 years]; 1305 male patients) were included. There was no evidence of a difference in progression risk between the ablation and resection groups after adjusting for confounders (hazard ratio, 1.46 [95% CI: 0.60, 3.56]; P = .40). Local recurrence was most frequent following ablation (ablation: 13 of 540 patients [2.41%]; resection: 12 of 1002 [1.20%]; nephrectomy: zero of 320 [0%]; P = .007), but was treatable with additional procedures. Distant metastasis was most frequent following nephrectomy (ablation: nine of 540 patients [1.67%]; resection: 19 of 1002 [1.90%]; nephrectomy: 14 of 320 [4.38%]; P = .02). Hospital stays were shortest for ablation (median hospitalization time: 0 days for ablation, 2 days for resection, 2 days for nephrectomy; P < .001). Ablation resulted in the fewest 30-day posttreatment hospital contacts (median number of contacts: one [IQR, 0-2] for ablation, one [IQR, 1-2] for resection, one [IQR, 1-2] for nephrectomy; P = .001), suggesting fewer complications with ablation. Conclusion In patients with T1a RCC, treatment with ablation demonstrated comparable progression risk but with fewer complications and shorter hospital stays. © The Author(s) 2026. Published by the Radiological Society of North America under a CC BY 4.0 license. Supplemental material is available for this article.