Interventional cryoablation stops cancer cold

Two papers presented at the Society of Interventional Radiology’s 33rd Annual Scientific Meeting show that cryoablation—the minimally invasive interventional radiology treatment to freeze primary kidney tumours without surgery—is 95 percent effective when the tumours are four centimetres or smaller and nearly 90 percent effective for tumours up to seven centimetres, when the disease is confined to the kidney at one-year follow-up.

 The one-year benchmark is established and well-accepted within the medical community to gauge the success rate of a treatment option because most kidney tumours would be visible at one year with a CAT scan or MRI.

“This interventional radiology treatment can effectively kill localized kidney tumours on an outpatient basis for most patients while offering a fast recovery time and an excellent safety profile,” said Christos Georgiades, M.D., Ph.D., interventional radiologist at Johns Hopkins Hospital in Baltimore, Md.

When the disease is confined to the kidney, the intent of treatment is curative. Using imaging to pinpoint the tumour, the interventional radiologist inserts a thin probe through the skin and guides it into the tumour below. The probe freezes and kills the tumour during the procedure.

The study at Johns Hopkins Hospital showed nearly 95 percent efficacy for localized tumours up to four centimetres and nearly 90 percent efficacy for tumours up to seven centimetres, with the lesions showing as dead tissue (scar) with no recurrences at one-year follow-up imaging. The ongoing study currently includes approximately 70 lesions in 60 patients with primary renal cell carcinoma.

Of the three patients who failed treatment (5 percent), one had a 10-centimetre tumour that physicians did not expect to cure, but there is only one centimetre of residual tumour that they plan to re-treat when the patient returns. The other two failures were in patients with larger tumours (7–10 centimetres), and physicians plan to treat those two patients again. One has only a half centimetre residual tumour 18 months later. Thus, the secondary efficacy (after retreatment) is expected to be close to 100 percent.

“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. The interventional radiology treatment is less invasive and easier on the patient,” noted Georgiades.

In addition to the patients who have the smaller tumours of four centimeters or less, this treatment offers a potentially curative option for patients with localized tumours who are not eligible for surgery. Many patients have other diseases that make surgery very high risk, cannot undergo the anaesthesia and do not have any other option. Also, people with borderline kidney function, only one kidney or multiple recurring tumours had no options until now, he explained.

“I want to get a message out, mostly to my colleagues, because they will encounter many patients who have these treatable cancers but they cannot have treatment or surgery because of other diseases. Until a few years ago, we in the medical community simply followed these patients; we didn’t treat the cancer for fear we may make things worse if we try to treat risky patients. But for many patients that’s no longer the case,” said Georgiades.

This interventional radiology treatment spares the majority of the healthy kidney tissue and can be repeated if needed. The treatment is very safe, and most patients are sent home the same day as the procedure. The rest go home the next day. The most common complication is a bruise (haematoma) around the kidney that goes away by itself.

The study from Barbara Ann Karmanos Cancer Institute in Detroit, Mich., involved 65 people and 81 masses, of which 61 were primary renal cell carcinoma (RCC), 6 oncocytoma, 1 angiomyolipoma, 8 renal benign or inflammatory lesions and 1 metastatic lesion. The average tumour size in this study was 2.8 centimetres. At 1.3 years average follow-up time (0.2–5 years), the majority of tumours continue to image as dead tissue. In contrast to heat, the cryoablation zone continues to shrink after cryotherapy, reducing up to 90 percent in volume by 12 months without scarring or strictures. Only 6 percent (5 of 81 tumours) had a local tumour recurrence, and these were limited to patients with multiple tumours in the kidney or an early probe failure. It is crucial to use enough cryoprobes to get sufficiently cold temperatures to kill all tumours and extend the visible ice approximately one centimetre beyond all tumour margins, similar to a surgical margin. Complications are avoided by liberal use of saline to push away the adjacent bowel, allowing tumours in nearly any location of the kidney to be treated.

“This interventional treatment is not a widely known procedure yet, even to other physicians, and patients are going to have to pursue it on their own,” added Georgiades.

(Source: 33rd Annual Scientific Meeting of the Society of Interventional Radiology, March 2008.: Society of Interventional Radiology: March 2008)