WASHINGTON D.C.—CT-guided percutaneous cryoablation of renal tumors appears to be a viable option for the treatment of selected small renal cell tumors, according to new data presented at the 2008 Society of Interventional Radiology 33rd Annual Scientific Meeting.
Using this technique, researchers have found it produces good short-term follow-up results with no major complications.
“This interventional radiology treatment can effectively kill localized kidney tumors on an outpatient basis for most patients while offering a fast recovery time and an excellent safety profile,” said lead investigator Christos Georgiades, MD, PhD, assistant professor of radiology and surgery at Johns Hopkins Hospital in Baltimore.
He presented data at this meeting from an ongoing study that includes the treatment of approximately 70 lesions in 60 patients with primary renal cell carcinoma. So far, the success rate has been remarkable, Dr. Georgiades said, with nearly 95% efficacy for localized tumors up to 4 cm and nearly 90% efficacy for tumors up to 7 cm. Of the three patients who failed treatment (5%), one had a 10 cm tumor that physicians did not expect to cure, but only 1 cm of residual tumor remains and they plan to re-treat the patient. The other two failures also were in patients with larger tumors (7-10 cm), and physicians plan to retreat those patients. One patient has only 0.5 cm residual tumor 18 months after the initial procedure. Dr. Georgiades said the secondary efficacy (after treatment) is expected to be close to 100%.
“The current gold standard treatment is laparoscopic partial nephrectomy surgery, but given the high success of interventional cryoablation that may change. We expect that the two treatments will be shown to be equivalent in a comparative study that is ongoing now at Johns Hopkins,” Dr. Georgiades said.
With this approach, a thin probe is inserted through the skin and guided into the tumor where the probe freezes and kills the tumor. It can be repeated if necessary and it spares the majority of the healthy kidney tissue. The majority of patients are sent home the same day as the procedure and the most common complication is a hematoma around the kidney that goes away by itself.
“We are in a new era,” Dr. Georgiades told Renal & Urology News. “What we hope is going to happen is that the care will become multi-disciplinary and the patients will be working closely with nephrologists, urologists and interventional radiologists. It will be collaborative and be part of comprehensive care.”
Although longer follow-up is required to gauge the efficacy of the procedure, said outcomes at one year are an established benchmark for gauging the success rate of a treatment for kidney tumors.
In a separate study, researchers at Eastern Virginia Medical School retrospectively evaluated the success, efficacy and safety of percutaneous CT-guided cryoablation of solid renal tumors at their institution. A total of 27 patients underwent 30 cryoablation procedures during a three-year period. The subjects included 14 men and 13 women with a mean age of 67 years (range, 58-80 years). Immediately prior to cryoablation, biopsy of the renal lesion was performed under CT guidance.
Up to four cryoprobes (mean 1.4) were positioned using CT imaging; lesions were ablated by using real-time CT imaging for intraprocedural monitoring of the ice ball formation. The team defined technical success as complete coverage of the tumor with the ice ball, with at least a 1 cm margin and elimination of areas of abnormal tumoral enhancement at imaging immediately following completion of the procedure. The researchers defined effectiveness as absence of suspicious enhancement on post-contrast imaging. They evaluated effectiveness during routine follow-up CT or MR at a mean time of 11 months (range, 0-30 months).
A total of 27 tumors were successfully ablated, with 24 of them requiring only one treatment session. The mean tumor size was 2.3 cm (range: 1.2 – 4.6 cm). Technical success was achieved in all 27 cases.
“We have had very good results and there were no serious complication in any of the patients,” said study investigator Mark Gibson, MD, a resident at Eastern Virginia Medical School in Norfolk. “Patient selection is very important. These are patients that urologists don’t want to operate on because they may be older, they may be poorer surgical candidates, and their tumors are usually small.”
He said there were three cases of recurrent tumor on routine follow-up imaging with a mean recurrence of 10 months (range, 6-12 months). All three recurrences were successfully retreated with repeat percutaneous cryoablation with no additional recurrences with a mean follow-up of nine months (range, 1-15 months). In addition, he noted that no major complications occurred.