LAUSR

To the editor, Renal cell carcinoma (RCC) patients with a recurrence after percutaneous ablation have several treatment options including surveillance, repeated ablation, radical or partial nephrectomy (RN/PN). Surgery after ablation is challenging due to the perinephric scarring that disturbs kidney mobilization with a high chance of complications in central lesions [3]. Therefore, repeated ablation may be an attractive nephron sparing method. In this case series, we report the results of nine RCC patients with residual disease (n = 7) or recurrent disease (n = 2) after prior microwave ablation (MWA) retreated with cryoablation (CA) between April 2018 and March 2019. The Visual ICE system (Boston Scientific, USA) was used in all patients and became available at our hospital in April 2018. Prior to that, most RCCs were treated with MWA [1]. Procedures were performed under general (n = 2) or epidural anaesthesia (n = 7). Pre-embolization was performed on the same day before the ablation in an adjacent artery (n = 2) to reduce the cold sink effect. Dissection was performed with 5% glucose and iodine solution (n = 3) or room air (n = 1). One patient received renal pelvis perfusion with warm sterile saline. A double freeze–thaw cycle was used consisting of 10 min freezing, 2 min passive thawing and 2 min active thawing. Median time between the last MWA and CA was 6 months (Range (R) 2–78). Primary tumours had a median size of 4.1 cm (R 2.3–4.8) and a median mR.E.N.A.L. nephrometry score of 11 (R 6–12). Sinus fat involvement was radiologically suspected in 2 lesions before CA (T3 disease). All recurrent lesions had an endophytic character with a close distance to the collecting system (\ 4 mm). Median follow-up was 24 months (R 12–32) during this period 6 out of the 9 patients (67%) showed persistent complete ablation (Fig. 1). No major complications occurred. Median reduction in glomerular filtration rate after CA was 6 mL/min/1.73 m. The three failures consisted of one residual lesion close to the ureter after a suboptimal first MWA that led to multiple recurrence sites. After, two CA’s, another recurrence developed without the ability for another ablation and finally a PN was performed successfully. The two other patients had suspected invasion in the renal fat (T3 disease) before CA and therefore CA was offered to gain local control. These two patients developed tumour invasion in the renal vein after 4 and 13 months (Fig. 2) and needed subsequent treatment by means of local and systemic therapy. & B. M. Aarts [email protected]