Renal cryoablation: Two techniques for managing small tumors

January 1, 2006

Peripheral lesions are more amenable to ablation and are technically easier, but endophytic neoplasms can be performed with precise intraoperative imaging.

Another approach has been laparoscopic or percutaneous ablation of the renal mass. As opposed to traditional excision, ablative techniques rely on energy sources to destroy tumors in situ. Hence, ablation represents a new paradigm in the management of small renal neoplasia. After briefly reviewing currently available ablation technologies and proper patient selection for an ablative procedure, this article focuses on two techniques for performing renal cryoablation.

The concept of ablation is not new to the field of urology. Certainly, most urologists are familiar with prostate brachytherapy or cryotherapy, in which cancers are destroyed without radical excision. However, within the realm of renal neoplasia, ablation is a relatively new advance. Initial studies regarding cancer control are excellent (up to 98% at 3 years) with lower complication rates than partial nephrectomy (<10% for cryoablation vs. 20% to 30% for laparoscopic partial nephrectomy) (BJU Int 2005; 96:1224-9; J Urol 2005; 173:42-7; J Urol 2005; 173:1690-4).

A number of ablative technologies are available, including cryoablation, radiofrequency (RF) ablation, and high-intensity focused ultrasound (HIFU). HIFU is not approved in the United States, and is still in its infancy. RF ablation and cryoablation are widely available. Overall, cryoablation offers improved monitoring, potentially better kill zones, lower chance of collecting system leak, less pain for the patient, longer-term data in larger patient series, and greater familiarity with its use among urologists.

RF ablation is likely less expensive than cryoablation, and radiologists are more familiar with its use than are urologists. Based on its numerous advantages over RF ablation, cryoablation is the preferred modality for renal tumor ablation. Nevertheless, controversy exists because RF technology has improved since the initial studies, with increased power and novel energy delivery methods.

Patient selection

Proper patient selection for an ablative technique is important. Those who present with small renal lesions or lesions in a solitary kidney are ideal candidates. Peripheral lesions are more amenable to ablation and are technically easier, but endophytic neoplasms can be performed with precise intraoperative imaging. Posterior lesions are more amenable to a retroperitoneoscopic approach or a percutaneous approach. Lateral or anterior lesions are more amenable to a transperitoneal laparoscopic approach.

Open cryoablation can be used by surgeons who are not trained in laparoscopy, but this approach is not ideal from a morbidity perspective. Overall, lesions less than 3 cm in size are ideal for ablation, but larger lesions also can be treated with a larger number of probes. Traditionally, cryoablation has been reserved for elderly patients with comorbidities. However, with the publication of excellent longer-term data, it may be offered in younger patients as long as they are monitored with serial imaging. No reports of metastases can be attributed to ablated lesions in young patients.

Ultimately, similar to prostate cancer, all treatment options and risks should be discussed with the patient, and an individualized decision should be made. As a general rule, I prefer partial nephrectomy in patients who are medically able to accept its greater invasiveness and morbidity. However, from medical and legal perspectives, given the low complication rate of cryoablation and its minimally invasive nature, it probably should enter into all treatment discussions, even if partial nephrectomy is preferred.