# Percutaneous Microwave Ablation Preserves Renal Function with Similar Long Term Oncologic Outcomes Compared to Surgery for Clinical T1 Renal Cell Carcinoma

## TL;DR

Microwave ablation is a less invasive treatment for early kidney cancer that preserves kidney function and has similar long-term cancer outcomes as surgery.

## Contribution

This study provides long-term comparative evidence that microwave ablation is as effective as surgery for early-stage kidney cancer while preserving renal function.

## Key findings

- Microwave ablation patients had lower perioperative complications and shorter hospital stays compared to surgery.
- Five-year metastasis-free and cancer-specific survival rates were similar between microwave ablation and partial nephrectomy.
- Renal function decline after microwave ablation was comparable to partial nephrectomy but significantly better than radical nephrectomy.

## Abstract

Microwave ablation is a minimally invasive, nephron-sparing treatment increasingly used for localized renal cell carcinoma, particularly in older or medically complex patients. However, long-term comparative data evaluating oncologic outcomes relative to surgery remain limited. In this study, we compared perioperative, renal functional, and oncologic outcomes among 2201 patients with clinical T1a and T1b renal masses treated with microwave ablation, partial nephrectomy, or radical nephrectomy. Patients treated with microwave ablation experienced significantly lower perioperative morbidity, shorter hospital stays, and renal functional preservation comparable to partial nephrectomy, despite greater baseline comorbidity. While local recurrence occurred more frequently following microwave ablation, metastasis-free and cancer-specific survival were similar to partial nephrectomy after adjustment for confounders. These findings support microwave ablation as an effective nephron-sparing treatment option for appropriately selected patients with clinical T1 renal cell carcinoma.

Background/Objectives: Percutaneous microwave (MW) ablation is a nephron sparing treatment for localized renal cell carcinoma (RCC). We compared perioperative, renal functional, and oncologic outcomes for clinical stage 1 RCC treated with MW ablation, PN, or RN. Methods: Adults with clinical T1 kidney masses treated with MW ablation, PN, or RN from 2001–2025 were identified. Outcomes included: 90-day overall and major complication rate, 30-day readmission rate, length of hospital stay (LOS), change in renal function, local recurrence-free survival (LRFS), metastasis-free survival (MFS), and cancer-specific survival (CSS). Univariable and multivariable analyses evaluated outcomes adjusted for confounders. Results: A total of 2201 patients with renal masses ≤ 7 cm and no evidence of locally advanced or metastatic disease were treated with MW ablation (708), PN (729), or RN (764). MW ablation patients were older and more comorbid compared to both PN/RN, whereas RN patients had larger, higher-grade tumors. Ninety-day overall complications were lowest after MW ablation (8.9% vs. 20.3% PN, p < 0.001 and 8.9% vs. 19.9% RN, p < 0.001). LOS was shortest after MW ablation (median 1 day vs. 3 days PN/RN, p < 0.001 for each). Six-month eGFR decline was similar after MW ablation and PN (−5.2% and −4.7%, p = 0.84) but greater after RN (−32.9%, p < 0.001). Local recurrences were more common with MW ablation, with five-year LRFS 96.4% versus 99.7% for PN (p < 0.001). Five-year MFS (99.5% vs. 99.7%, p = 0.24) and CSS (99.3% vs. 99.7%, p = 0.71) did not differ between MW ablation and PN. Conclusions: Percutaneous MW ablation has comparable metastasis free and cancer specific survival with lower perioperative morbidity and comparable renal preservation to PN, despite worse baseline comorbidity and renal function. These findings support MW ablation as an effective nephron-sparing option for appropriately selected patients with clinical T1 RCC when performed at an experienced center.