Freezing effective for kidney tumors

ROCHESTER, Minn., March 29 (UPI) -- The freezing method cryoablation killed more than 90 percent of malignant kidney tumors, in a U.S. study at Mayo Clinic.

Although there have been only two to four years of follow-up, no patient who underwent a successful procedure has needed further therapy, the researchers said.

The trial involved 40 people with kidney cancer diagnosed between 2003 and 2005.

The researchers said that cryoablation works better than radiofrequency ablation for kidney cancer because it can treat tumors larger than 3 cm; also, the edge of the frozen tissue can be accurately monitored with CT scans to ensure that the total tumor mass is treated. Neither can be done in radiofrequency procedures.

Cryoablation uses hollow needles filled with argon gas to freeze the tissues in which they are embedded to minus 100 degrees Centigrade. The tissue is thawed by replacing the argon with helium, and after at least two cycles of freezing and thawing the needles are withdrawn. Patients are hospitalized overnight.

A report on the study was published in the March issue of Radiology.