THE phrase 'bone chilling' has taken on a new, literal sense.
Tumours in bones can now be cut out cleanly by first freezing them into rock-solid masses at a temperature of minus 100 deg C.
Less blood and bone is lost in this form of surgery called cryosurgery, achieved by training high-pressure jets of supercooled argon gas at the tumour before it is cut out.
This new treatment method at the National University Hospital (NUH) has been offering a new lease of life to bone cancer patients for whom conventional treatment is unsuitable or has failed.
These include patients whose cancers started elsewhere and spread to the bones, or those whose bone tumours have recurred.
The treatment also works for some patients whose tumours start in the bone. With such patients, the tumour is scraped out before a margin of the surrounding unaffected bone is frozen.
The freezing kills stray tumour cells that may be lurking there, and cuts down the risk of the tumour recurring from between 30 and 50 per cent to 8 per cent.
However, Assistant Professor Saminathan Suresh Nathan, a consultant at NUH's department of orthopaedic surgery, said that cryosurgery works only on certain tumours, depending on the kind of cells they are made of.
When it works, though, this treatment method gives 'a superior level of control - an edge we've never had before', he said.
The treatment can help about half the 13,000 people here who get bone tumours, benign or otherwise, he estimated.
Till now, patients with tumours only in the bones have typically undergone conventional surgery which involves scraping out the affected parts of the bone.
The recurrence rate is high, and if the tumour does return, the entire affected bone has to be removed.
Cryosurgery slashes the risk of recurrence, and unaffected bone can be saved, said Prof Nathan, who has operated on a dozen patients here this way since 2006.
Patients whose cancers began growing elsewhere and then spread to the bones are usually given radiation therapy, but this often does not stop the cancer from spreading.
Others may have tumours that bleed too much when cut, making conventional surgery too dangerous.
Without cryosurgery, these patients become crippled or bedridden, and eventually die.
Before the treatment using argon gas was developed, cryosurgery was performed by pouring liquid nitrogen through a funnel to freeze tumours before removing them.
This has hardly been done here because it is risky: The liquid nitrogen could spill and burn the patient's skin, causing wounds which may later become infected.
The nitrogen could also enter the bloodstream and expand into a bubble, which can block circulation and cause brain damage, heart failure or even death.
Under the new, safer technique, argon gas is pumped by a computer into the tumour under high pressure through metal probes.
None of the 12 patients who have undergone this procedure has seen tumours return, and they have become more mobile as well, said Prof Nathan.
The procedure costs about $2,400 to $4,220 at NUH.
This article was first published in The Straits Times on June 7, 2008.
