Mayo Clinic researchers report that freezing kidney tumors through percutaneous cryoablation shows promise for patients who are not good candidates for surgery.
Their early findings showing short-term success in more than 90 percent of selected patients are published in this month's issue of Radiology.
The standard treatment for kidney tumors is surgery, providing a high likelihood of a long-term cure. For some patients, surgery is not an option, and Mayo's urologists and radiologists collaborated to find alternatives for these individuals. If these patients are frail due to age or illness or are not able to have surgery because of other factors, percutaneous cryoablation may be an option.
"This procedure appears to be a good option for some patients," says Thomas Atwell, M.D., Mayo Clinic radiologist and the study's primary investigator. "It makes their hospital stay and recovery time very short and surgical stress is minimal." He cautions that this procedure is not ideal for everyone, noting that it is an option for only a relatively small subset of patients.
Percutaneous ablation uses needles to penetrate the skin and deliver directly to the tumor either high-intensity, tissue-destroying heat through radiofrequency ablation, or freezing cold through cryoablation. Mayo Clinic's radiologists are among the most experienced in the world in performing ablation techniques, and have treated nearly 300 kidney tumors either with radiofrequency ablation or cryoablation. Radiofrequency ablation (RFA) burns away the tumor, while cryoablation freezes it.
Mayo Clinic doctors had previous experience with liver tumor cryoablation when they added kidney tumor cryoablation in 2003. Today's report contains the largest published results for percutaneous cryoablation patients. Mayo researchers report that not only can this technique be an alternative to surgery, but that in some cases, it has benefits over RFA.
Previous experience in percutaneous RFA led the researchers to recognize that it has two important limitations. Tumors larger than 3 centimeters are difficult to treat with RFA, with increased rates of technical failures and tumor recurrence. Also, the area being treated cannot be effectively monitored with computed tomography (CT) or ultrasound. The Mayo study findings show that cryoablation can be used for some larger tumors with simultaneous operation of multiple cryoprobes guided by ultrasound. The ablation margin (the edge of the frozen tissue) can be accurately monitored with CT, to ensure that the total tumor mass is treated.
The researchers reviewed the records of the 23 men and 17 women with kidney cancer treated with percutaneous cryoablation at Mayo Clinic between March 12, 2003, and Aug. 4, 2005. They found that this treatment was chosen over RFA for reasons such as larger tumor size, proximity of tumor to ureter or bowel, or a central location on the kidney. Cryoablation was successful in 38 of the 40 patients, with no repeat treatment necessary.