CT-Guided Percutaneous Cryoablation in Renal Cell Carcinoma: Factors Affecting Local Tumor Control

Purpose: To retrospectively evaluate factors affecting local tumor control in cryoablation of renal cell carcinomas (RCCs). Materials and Methods: This study examined 61 patients (43 men, 18 women) with a mean age of 69.1 years +/- 10.8 (range 38-87 y) who underwent computed tomography (CT) guided percutaneous cryoablation for a single RCC and were followed for 6 months or longer. Maximum tumor diameter was 0.8-4.8 cm (mean +/- standard deviation, 2.4 +/- 0.9 cm). Factors affecting local tumor control were evaluated. Deep tumor location was defined as the center side of the body perpendicular to the kidney midline. Results: Median follow-up was 12.7 months. Residual unablated tumors and local tumor progression were observed after initial cryoablation in 4 patients each (13%, 8 of 61). All uncontrolled tumors were located in the deep side of the kidney (100%, 8 of 8), and were covered by an ice-ball margin of 5 mm or less. Deep tumor location (P = .005) and ice-ball margin (P = .002) were detected as significant factors affecting local tumor control on univariate analysis, and ice-ball margin remained significant in a stepwise logistic regression model (P = .006; odds ratio, 0.57; 95% confidence interval, 0.38-0.83). Complete tumor control rates were 42.9% (3 of 7), 92.6% (50 of 54), and 100% (20 of 20) with ice-ball margins of less than 3 mm, 3 mm or larger, and 6 mm or larger, respectively. Conclusions: Deep tumor location and ice-ball margins less than 6 mm were associated with incomplete local control following CT-guided percutaneous cryoablation for RCC.