Cryotherapy is often portrayed as radiofrequency ablation's little brother. But the thermal ablation technique is proving safer and more effective than previously thought, according to several papers presented at the RSNA meeting. Cryotherapy can also muscle in on malignancies affecting several organ systems, including the liver, lungs, and kidneys.
Dr. Hussein D. Aoun, a radiologist at Wayne State University Medical Center in Detroit, presented two studies assessing the ability to use cryotherapy to ablate liver and lung tumors. The first evaluated CT-guided treatment of 70 masses with 58 procedures in 47 patients.
Aoun and colleagues found cryotherapy provides a visually reliable and effective treatment alternative to its heat-based brethren. The team successfully treated lesions 3.4 cm in average size, including large masses near blood vessels, with a recurrence rate of 9.7% at two-year follow-up.
The technique is virtually painless and allows use of auxiliary devices unsuitable for RFA, such as balloons, to protect tumor-adjacent organs. It thus proves particularly amenable to patients with anesthesia-related risks and tumors near painful sites, such as the diaphragm or the chest wall, Aoun said.
The second study released data for CT-guided treatment of 56 primary and metastatic lung tumors with 51 procedures in 36 patients. Cryotherapy successfully ablated tumors 3.1 cm in average size, with a two-year recurrence rate of 16.1% for masses.
"Cryotherapy doesn't seem to be as sensitive to tumor size or vessel proximity, because we can actually sculpt the isotherm freezing directly into central structures of almost any area. We learned all this from years of work in the prostate. This is all well-defined science," said coauthor Dr. Peter J. Littrup, a professor of radiology, urology, and radiation oncology at Wayne State.
In another study, Dr. Thomas Atwell presented results on successful percutaneous cryoablation of 59 renal tumors in 58 patients treated from March 2003 to date. Atwell and colleagues placed cryoprobes under ultrasound guidance and monitored ablation results with CT. They achieved a 97% technical success with a mean tumor ablation size of 3.4 cm and only one major complication (hemorrhage). Biopsy confirmed renal cell carcinomas (53%), oncocytic neoplasms (11%), and oncocytomas (28%). Researchers currently have nine-months worth of follow-up for 42 ablated tumors that remain recurrence-free.
Percutaneous ultrasound/CT-guided or monitored cryoablation is a relatively safe method of treating renal tumors in selected patients. Short-term results show promise, but only long-term outcomes will confirm its effectiveness, Atwell said.
