Long-term oncological outcomes following percutaneous microwave ablation of T1 renal cell carcinoma.

Objectives: Incidence of small renal masses (SRMs) including renal cell carcinoma (RCC) is increasing. Standard of care is to offer partial nephrectomy (PN), with tumour ablation (TA) considered an alternative in frail/co-morbid patients. This study aimed to determine whether microwave ablation (MWA) is a safe and effective treatment for selected cases of RCC.

Methods: All MWAs performed at a regional tertiary care centre between October 2016 and April 2024 were prospectively recorded on a database. Data collected included tumour and patient characteristics, complications and recurrences.

Results: 209 MWAs were recorded with median 37 months (interquartile range [IQR] 15.3-59.4 months) follow up. 94.7% of patients had ≥ 12 months of follow-up. The biopsy rate was 92%. Following MWA, 93% of patients had a hospital stay of 1 night. Two Clavien-Dindo grade ≥ III complications occurred within 30-days (0.96%). Local and metastatic recurrence rates were 5.9% and 2.7% respectively.

Conclusions: MWA was a safe, effective treatment for SRMs in this large cohort which included young, fit patients and underwent long term follow up. Recovery times were short, with low complication rates and favourable oncological outcomes in biopsy-proven T1 RCC <5cm.

Advances in knowledge: The current study demonstrates a large, diverse MWA cohort (including T1b tumours) with high biopsy rate, minimal loss to follow-up and long follow-up period facilitating assessment of long-term oncological outcomes in biopsy-proven RCC. The results support MWA as a safe, effective treatment for cT1a RCC that should be offered to patients as part of shared decision making.