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CHICAGO – Researchers here suggested that metastatic tumors that go to the lung can be successfully eradicated using cryotherapy -- literally turning the masses into ice balls that are then resorbed by the body.

With more than 21 months of follow-up, the overall recurrence rate of the metastases attacked in the study was 6.2% – with 1.9% within the cryozone and 4.3% outside the cryozone, reported Salah Abdelhadi, MD, a diagnostic radiologist at Wayne State University/Detroit Medical Center.

Central organ tumors tended to recur more frequently in the study -- about 8% of the 99 centrally located masses recurred, compared with 5% of the 159 peripherally located masses (P=nonsignificant), Abdelhadi said in an oral presentation at the annual scientific sessions of the Radiological Society of North America.

"Tumors larger than 3 cm had a recurrence rate of 13.6%, compared with 4.7% for the smaller lesions, P<0.05."

The complication rate was also considered low, Abdelhadi said. Overall, 3.7% of the patients treated with cryoablation had a complication -- 2.4% in the centrally located tumors and 4.6% in the peripheral ones; 9.6% of the larger tumors carried a complication risk, compared with 2% of the smaller tumors. He reported four grade 3 cases of pneumothorax, all occurring with tumors at the periphery. There was one grade 4 complication -- a pleural hemorrhage that occurred post-procedure in a 4 cm mass. That patient required drainage, treatment in the intensive care unit, and blood transfusion.

"The advantages of cryoablation of the lung masses include excellent visualization of the effect of the ice ball that freezes the lesion and the ability to avoid nerves and other structures such as the esophagus. The procedure is associated with little pain, and does not discriminate in tissue types and holds the potential for a cryoimmune response."

Abdelhadi explained that the cryoablation technique includes a triple-freeze protocol, opposed to double-freeze techniques: The tumor is frozen for 3 minutes, thawed for 6 minutes, frozen for 10 minutes, followed by a 13-minute thaw period, and finally frozen for 20 minutes.

In the study, there were 109 patients who underwent 191 procedures for a total of 258 masses, Abdelhadi said. Most of the metastases came from sarcomas: 103 cases -- 56 colorectal metastases and other metastases from numerous cancer types. A total of 66 patients had multiple procedures -- as many as six; in 48 procedures multiple tumors were frozen – up to seven different masses.

The average tumor size was 2 cm, and the average ablation zone was 4.3 cm; the mean follow-up has been 21.6 months, with 130 cases for longer than 12 months, and patients have been out as long as 8.3 years, Abdelhadi said. There were 44 tumors larger than 3 cm, and 214 were 3 cm or smaller.

The moderator of the session where the study was presented, Hyun Kim, MD, chief of interventional radiology at Yale School of Medicine in New Haven, Connecticut, told 木瓜直播: "We do transcatheter therapy for liver cancer all the time, but doing it for lung cancer is sort of novel. It is not something that is standard of care. But being aware of the lung vasculature, there is very little discomfort in doing this procedure. The lung is a very forgiving organ.

"At the present time there are a lot of niche applications for treatment of these masses. It is really center-specific, and some centers do use cryoablation as well as radiofrequency or microwave ablation procedures."

Kim said the findings of the Detroit group using cryoablation are about when he would expect: "At the end of the day we will probably have a choice of all these modalities including transcatheter and percutaneous. I think it really depends more on the comfort zone of the practicing doctor as to what method is selected to treat these patients."