Risk Factors for Residual Unablated Tumour Following CT-Guided Percutaneous Renal Cryoablation: Lessons from the EuRECA Registry

Objective To assess tumour factors that reduce primary technical efficacy (PTE) from CT-guided renal cryoablation. Methods Patients were taken from the EuRECA registry between December 2014 and November 2020. To focus on tumour factors rather than individual technique, this study was limited to cases using CT and excluded procedures using cone beam, US, MRI, or laparoscopy. PTE was assessed per tumour and defined as complete ablation of the target on enhanced CT or MRI by 90 days. Residual unablated tumour (RUT) was defined as focal persistent tumour enhancement within 90 days. Results A total of 1,424 tumours from 11 different centres were eligible; 38 episodes of RUT were detected giving an overall PTE of 97.3%. The factors most likely to be associated with RUT were as follows and persisted in multivariate logistic regression. Tumour contact with a central artery or vein; increased OR of 5.29 (CI 2.59-10.81 p < 0.001), PTE was 89.8% in this group. Tumours size; T1b vs T1a increased OR of 2.31 (CI 1.10-4.87 p = 0.0276), T1b PTE was 94.1% vs T1a PTE 97.9%. Close proximity to the collecting system (< 4 mm) was significant at univariate logistic regression (OR 2.87, P = 0.028), as was a RENAL complexity score of 10 or above (OR 2.71, p = 0.0147), but neither was significant in the multivariate analysis. Conclusions Overall, CT-guided percutaneous renal cryoablation has a high PTE at 97.3%. In this analysis, the most significant risk factor for RUT is central renal vessel contact. T1b tumours are also noted to have an increased risk of RUT compared to T1a.