Cryoablation for the Treatment of Small Renal Tumors
Peter Langenstroer, MD, MS, Associate Professor of Urology
The management of small renal masses is a dynamic and evolving process. Twenty years ago, the mainstay management for small renal masses was radical nephrectomy. This resulted in over-treatment of many patients. It has become evident that radical nephrectomy is a significant risk factor for the development of chronic renal disease. More recently, chronic renal insufficiency has been associated with increased risk of cardiovascular events, hospitalizations and mortality. Patients undergoing renal preservation, e.g., nephron sparing surgery, have better overall quality of life than patients undergoing radical nephrectomy. Thus, nephron sparing surgery has become the contemporary standard of care for the management of small renal masses. Cryoablation of renal tumors was introduced as an ablative modality to manage renal masses in the late 1990s. In February 2000, physicians at Froedtert & The Medical College of Wisconsin treated the first patients with laparoscopic renal cryoablation. Since then, we have performed more than 250 such ablations using laparoscopic or percutaneous methods. The advantage of this minimally invasive ablative technique is that it allows real time monitoring of the ablative process. The result is thermal destruction of the renal mass. Patients experience decreased hospitalization, decreased post-operative pain, less morbidity and early return to baseline functioning. The traditional open partial nephrectomy typically involves a four to five day hospitalization; in contrast,with laparoscopic cryoablation, hospitalization is typically one to two days.
To further minimize morbidity, we performed our first percutaneous cryoablation in January 2007. The percutaneous approach is an outpatient procedure that allows return to normal activities within one to two days. Follow up for cryoablative procedures requires imaging with computed tomography (CT) scans or magnetic resonance imaging (MRI) to monitor the effectiveness of the ablation. The initial scan is performed at three months and acts as a baseline for future scans. Parenchymal enhancement in the base of the ablative site is considered a recurrence. Outcomes for this procedure have been excellent. To date, the recurrence rate remains less than 5 percent. Loss of renal function is negligible and the radiographic treatment success rate is equivalent to that of contemporary partial nephrectomy series. Froedtert & The Medical College of Wisconsin have one of the largest cryoablation series in the country with some of the longest follow up. Based on our experience, we believe this technique has proven itself a viable option for the management of patients with small renal masses.