Renal functional outcomes after cryoablation of small renal masses

Renal function outcomes after renal cryosurgery have not been widely scrutinized. We report 2-year renal function outcomes from a single-center cohort of patients who were treated with cryoablation for small renal masses.

We performed a retrospective review of our laparoscopic and percutaneous renal cryoablation experience between January 2003 and April 2007. Global renal function was assessed using measured serum creatinine and estimated glomerular filtration rate (eGFR) (MDRD equation). Chronic kidney disease (CKD) was defined as a serum creatinine level >2.0 mg/dL or eGFR <60 mL/min/1.73 m(2).

Sixty-two patients were included in the analysis. Mean follow-up was 30 months (range 13-63 mos). Mean tumor size was 2.33 cm (range 1-4.6 cm). Comorbid conditions were prevalent: 77% hypertension, 35% hyperlipidemia, 31% diabetes mellitus, 39% tobacco use, and 32% heart disease (coronary artery disease/congestive heart failure). Based on eGFR calculations, preoperative CKD was noted in 17 of 62 (27%) patients. De novo CKD was noted in 5 of 45 (11%) patients. Patients in whom de novo CKD developed had lower pretreatment eGFR (71.0 vs 98.4 60 mL/min/1.73 m(2), P = 0.03) and larger tumor size (2.94 vs 2.19 cm, P = 0.04) compared with patients who were maintaining normal renal function. When CKD was defined as creatinine level >2.0 mg/dL, only one and six patients were identified with preoperative and de novo CKD, respectively.

In a cohort of renal cryosurgery patients who were characterized by highly prevalent medical comorbidities, renal function was generally well maintained, with a low rate of de novo CKD based on eGFR calculations. A serum creatinine level >2.0 mg/dL was a less sensitive measure of CKD.