Cryoablation is for those who are unfit for surgery, and (above) MRI-guided cryotherapy

Mohan Mehta, 74, lies in his hospital bed, despondent and listless. He has a tumour in his kidney but he can’t be operated upon. Thanks to his advancing years and weakness following prolonged illness, he has been deemed unfit for surgery.

But there’s good news for Mehta. Mayo Clinic researchers have found a novel technique of freezing kidney tumours through a process called percutaneous cryoablation. The findings, showing short-term success in more than 90 per cent of select patients, were recently published in Radiology, the journal of the Radiological Society of North America (RSNA).

So what is it all about? “Cryoablation is a new method of treating select tumours by freezing them,” explains Thomas D. Atwell, instructor of radiology, Mayo Clinic School of Medicine in Rochester, Minnesota. “The patient is either sedated or given general anaesthesia. Cryoprobes (instruments to apply extreme cold to tissues) are then placed through small (4-5 mm) skin incisions and guided into the tumours using CT (computed tomography) or ultrasound imaging. Once the cryoprobes are in place, the tumours are frozen over 20-30 minutes. The cryoprobes are then withdrawn and band-aids placed on the skin. Patients are kept in the hospital overnight for observation.”

The technique is the result of a collaboration between Mayo’s urologists and radiologists. It is an easy procedure with minimal pain and a quick recovery time, adds Atwell, the study’s primary investigator.

The researchers reviewed the records of 23 men and 17 women with kidney cancer who were treated with this method at Mayo Clinic between March 12, 2003, and August 4, 2005. They found that this therapy scored over radio frequency ablation (RFA, the more popular method) which burns away the tumour.

This was mainly because of the larger tumour size, the proximity of the tumour to the ureter or bowel, or a central location on the kidney. The new method was successful in 38 of the 40 patients, with no repeat treatment required.

Cryoablation scores over RFA techniques on several counts. Claims Atwell, “First, the radiologist can monitor the ablation by visualising the ice-ball with a CT scan or an MRI. Second, cryoablation allows treatment of larger kidney tumours with simultaneous operation of multiple cryoprobes guided by ultrasound.” And the ablation margin (the edge of the frozen tissue) can be accurately monitored with CT to ensure that the total tumour mass is treated. This makes it a much safer method. However, RFA is still considered important, particularly in the treatment of smaller and peripherally located tumours, says Atwell.

The cost of the new technique is dependent on several factors but is much less than that in surgery. Says Atwell, “We have treated over 90 patients with cryoablation and have achieved 95 per cent success. However, our follow-up remains short and until we can prove the durability of the method, we recommend it only to those who are at risk of undergoing surgery.”

What about the feasibility of the technique in India? Says Murali Dhar Raibagi, a nephrologist at Apollo Gleneagles Hospital, Calcutta, “Currently, we do treat tumours using RFA. So importing the cryo technique won’t be difficult; it will only take time.”

However, not everyone is as optimistic. Says Dr Indrajit Chatterjee, formerly at D.S.P. Main Hospital, Durgapur, “It might be difficult to import the technology to India for several reasons such as lack of knowledge and experience trials.”

All said and done, cryoablation is a very recent technique. “It lacks long-term follow-up,” agrees Dr Atwell. “We thus can’t be confident of its role in definitive tumour management. And hence surgical removal of the tumour remains the gold standard.” Also, if the renal tumour is too close to another organ, the freezing temperatures could cause damage.

But then, for some patients, cryoablation seems to be their only chance of survival. Mohan Mehta would agree.