Acute histologic changes in human renal tumors after cryoablation

Background and Purpose: Cryoablation is a treatment option for some patient s with small, exophytic lesions of the kidney. Several investigators have e valuated the effects of cryoablation in normal renal tissue of animals, The purpose of this study was to investigate the tissue changes following cryo ablation in human renal tumors. Patients and Methods: We prospectively evaluated patients with solid renal lesions (1.5-1.8 cm) confirmed by CT, MRI, or both. Metastatic work-up for all patients was negative. All lesions were biopsied prior to freezing. Two patients with bilateral renal tumors underwent argon-gas-based CRYOcare Sy stem (Endocare, Irvine, CA) treatment via an open approach. A 3-mm cryoprob e was placed directly into each tumor, A single 15-minute freeze preceded a n active thaw (helium gas) for each lesion. Iceball dimensions were monitor ed by intraoperative ultrasonography, After successful cryoablation, partia l nephrectomy was performed to remove the lesion, and the renal tissue unde rwent histologic evaluation. Results: The cryoprobes achieved a temperature of -135 degrees C, No bleedi ng was noted, and there were no intraoperative or postoperative complicatio ns with a mean follow-up of 3 months. Histologically, freezing of renal tis sue resulted in coagulative necrosis and hemorrhage beyond the boundaries o f the lesions. There was a zone of demarcation between the viable and nonvi able tissue. Conclusions: In our series, cryoablation was effective in destroying tumor tissue in vivo in human kidneys, Freezing was sufficient to achieve a negat ive surgical margin. Cryoablation of renal tumor is an alternative to the c urrently available nephron-sparing surgical techniques. The long-term effec t of tumor tissue destruction by cryosurgery requires further investigation .