In Vitro Assessment of the Efficacy of Thermal Therapy in Human Renal Cell Carcinoma

Objectives: To define the temperature-time points that result in cell death in a human renal cell carcinoma cell (RCC) line in vitro. Methods: Cellular viability and clonogenic cell survival were determined for human A498 RCC cells after thermal treatment. Various temperature (45°C to 70°C) and time (1 to 30 minutes) combinations were used. Cell viability was assessed by vital dye uptake and clonogenic cell survival. Mathematical Arrhenius modeling was performed to construct a graphic display of A498 cell thermal sensitivity. Results: Temperature-time points at which 99% or greater cell death occurred according to the vital dye assay were 55°C for 30 minutes, 60°C for 10 minutes, and 65°C for 8 minutes. Clonogenic survival studies confirmed that cells treated at these temperature-time points failed to grow even after 10 days. Conclusions: These in vitro results show that short exposure to temperatures higher than 70°C is lethal in the A498 RCC cell line. Lower temperatures in the 60°C range require more prolonged heating to cause cell death. Knowledge of these temperatures will be useful to better plan and monitor complex radiofrequency ablations.