Background Percutaneous ablation for cT1 renal cell carcinoma (RCC) remains underused, partially because of heterogeneous and limited long-term outcomes data assessing recent cryoablation methods. Purpose To report intermediate- to long-term outcomes of image-guided percutaneous cryoablation of cT1 RCC and to compare outcomes for CT versus MRI guidance. Materials and Methods This HIPAA-compliant retrospective single-institution study assessed patients who underwent percutaneous cryoablation for solitary pathology-proven cT1 RCC between August 2000 and July 2017. Tumors (cT1a, = 282; cT1b, = 25; size range, 0.6-6.5 cm; median size, 2.5 cm) underwent cryoablation with CT ( = 155) or MRI ( = 152) guidance. Primary end points of overall survival (OS), disease-specific survival (DSS), imaging-confirmed disease-free survival (DFS), and local progression-free survival (LPFS) were calculated by using Kaplan-Meier analysis. Secondary end points of technique efficacy and adverse event rate were also calculated. Primary and secondary end points for CT and MRI guidance were compared by using univariable regression analysis. Results A total of 307 patients (mean age, 68 years ± 11 [standard deviation]; 192 men) were evaluated. Median clinical follow-up lasted 95 months (range, 8-219 months), and median imaging follow-up lasted 41 months (range, 0-189 months). Survival metrics at 3, 5, 10, and 15 years, respectively, included OS of 91% (95% confidence interval [CI]: 88%, 94%), 86% (95% CI: 82%, 90%), 78% (95% CI: 73%, 84%), and 76% (95% CI: 69%, 83%); DSS of 99.6% (95% CI: 99%, 100%), 99% (95% CI: 98%, 100%), 99% (95% CI: 98%, 100%), and 99% (95% CI: 98%, 100%); DFS of 94% (95% CI: 92%, 97%), 91% (95% CI: 88%, 96%), 88% (95% CI: 83%, 93%), and 88% (95% CI: 83%, 93%); and LPFS of 97% (95% CI: 94%, 99%), 95% (95% CI: 93%, 98%), 95% (95% CI: 93%, 98%), and 95% (95% CI: 93%, 98%). Survival did not significantly differ between CT and MRI guidance, with univariable Cox regression analysis hazard ratios of 0.97 (95% CI: 0.57, 1.67; = .92) for OS, 0.63 (95% CI: 0.26, 1.52; = .30) for DFS, and 0.83 (95% CI: 0.26, 2.74; = .77) for LPFS. Primary and secondary technique efficacy were 96% and 99%, respectively. Overall adverse event rate was 14% (43 of 307), including 11 grade 3 events and three grade 4 events according to the Common Terminology Criteria for Adverse Events. Conclusion Percutaneous CT- and MRI-guided cryoablation of cT1 renal cell carcinoma had similar excellent intermediate- and long-term outcomes. © RSNA, 2020 See also the editorial by Georgiades in this issue.

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