Incidence of Multiple Sporadic Renal Cell Carcinomas in Patients Referred for Renal Radiofrequency Ablation: Implications for Imaging Follow-Up

The objective of our study was to report the incidence of multiple sporadic primary renal cell carcinomas (RCCs) in patients referred for radiofrequency ablation (RFA).A retrospective search identified 162 patients (104 men and 58 women; mean age, 74 years) without a history of von Hippel-Lindau disease with a total of 175 tumors treated with RFA for biopsy-proven primary renal malignancies at our institution from 1998 to 2009. Three groups of patients with multiple RCCs were identified: patients with a history of nephrectomy for RCC who had been referred for RFA of a new renal tumor, patients who presented with multiple renal tumors at the time of referral for RFA, and patients who were shown to have developed a new renal tumor on follow-up imaging after RFA.Twenty-eight patients (17%) had multiple biopsy-proven RCCs. Eighteen patients (11%) had undergone prior nephrectomy for surgically proven RCC. The mean interval between prior nephrectomy and RFA referral was 122 months (range, 12-456 months). Seven patients (4%) without a history of nephrectomy presented with two biopsy-proven RCCs at RFA referral. Three patients (2%) who had not undergone nephrectomy and had a solitary RCC at the time of RFA had developed a new biopsy-proven RCC separate from the original treatment site on follow-up imaging after RFA. The mean time to diagnosis from the initial RFA treatment was 52 months (range, 25-89 months).Imaging surveillance of patients referred for renal RFA may be important not only to assess treatment success but also to detect new RCCs.