Evolving Role for Cryoablation in Treating Small Renal Masses



Selected “healthy” patients with clinical T1 renal cell carcinoma may be safely treated with percutaneous cryoablation, according to a single-center study of experience at the Mayo Clinic.1


In healthier patients, our experience shows that cryoablation achieved good short-term oncologic control with an excellent safety profile. Longer follow-up data are needed to evaluate the durability of response.
— Harras B. Zaid, MD

“In healthier patients, our experience shows that cryoablation achieved good short-term oncologic control with an excellent safety profile,” said lead author Harras B. Zaid, MD, second-year fellow in urologic oncology at the Mayo Clinic, Rochester, Minnesota. “There is a potential role for repeat ablation following local recurrence. Longer follow-up data are needed to evaluate the durability of response. We conclude that cryoablation should be considered in healthier patients, particularly those with challenging surgical anatomy.”

NCCN, AUA Guidelines

Over the past decade, there has been a shift from radical nephrectomy to partial nephrectomy for the management of clinical stage T1 renal masses. Observation and thermal ablation are also options for select patients, though the adoption of these techniques has been slower to catch on, with the exception of specific centers such as the Mayo Clinic.

Guidelines from the National Comprehensive Cancer Network® (NCCN®) and the American Urological Association (AUA) highlight the use of thermal ablative techniques (ie, radiofrequency ablation or cryoablation) for nonsurgical candidates, Dr. Zaid told listeners at the 2017 Genitourinary Cancers Symposium in Orlando, Florida.

“Current evidence suggests that partial nephrectomy and percutaneous ablation have excellent outcomes for treatment of clinical T1 masses, with no difference in local recurrence-free rates. These data are for all comers, including patients with multiple comorbidities,” Dr. Zaid explained. “Use of cryoablation has been limited in healthy patients who are otherwise candidates for surgery.”

Study Details

Dr. Zaid reported data from a single-institution review of patients undergoing percutaneous cryoablation from 2001 to 2015 who were 65 years old or younger and had solitary kidney masses. He focused on the results in healthy patients only (43 of 705 treated with cryoablation). The median age of the healthy cohort was 57 years. Seven patients (16.3%) had a prior partial nephrectomy, and 5 patients (11.6%) had a solitary kidney.

Cryoablative Alternative for Small Renal Masses

  • Based on a single-institution experience, cryoablation seems to be as safe as partial nephrectomy (the gold standard) for the treatment of small renal masses in healthier patients.
  • Cryoablation has been reserved for elderly patients or those with difficult anatomy for surgery.
  • Longer follow-up is needed to determine recurrence rates in this younger healthier cohort, and larger studies should compare cryoablation vs partial nephrectomy in this population.

The vast majority of masses were clinical stage T1a (n = 40), and 3 masses were stage T1b. The median tumor size was 2 cm. A total of 27 masses (63.7%) were biopsy-proven renal cell carcinoma, and 6 masses (13.6%) were benign; histology was unknown in 10 (22.7%). Twenty-five percent had multiple prior surgeries.

“Over time, the technique has improved significantly at Mayo. First the patient sees a urologist and then a radiologist. The patient is admitted overnight post procedure to the urology service, and follow-up is with a urologist,” reported Dr. Zaid.

Cryoablation is performed with the patient under general anesthesia, with computed tomography guidance for placement of the probes. Imaging is performed in real time every 2 to 4 minutes during freezing to identify the ice ball. Patients are monitored closely for hematoma and other complications. Follow-up is conducted at 3 and 6 months and then, depending on the case, every 6 months or 1 year.

Key Findings

At a median radiologic follow-up of 22 months, only 3 patients developed a complication. One patient (1.3%) had local recurrence, and two patients (2.6%) developed metastases. The patient with local recurrence underwent repeat ablation, with no evidence of recurrence to date. The patients who developed metastases had prior nephrectomy with high-risk pathology. There were no deaths during the study.

Dr. Zaid acknowledged that this was a small cohort and a single-institution study of healthier patients and that longer follow-up is needed to establish the durability of control. ■

Disclosure: Dr. Zaid reported no potential conflicts of interest.

Reference

1. Zaid HB, Atwell TD, Schmit G, et al: Cryoablation of cT1 renal masses in the “healthy” patient: Early outcomes from Mayo Clinic. 2017 Genitourinary Cancers Symposium. Abstract 433. Presented February 18, 2017.


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