Approved by the National Institute for Clinical Excellence (NICE)  in 2005, Cryotherapy works by the insertion of a number of metal probes, which are put through the skin and into the affected part of the prostate.  The probes contain liquid nitrogen or argon, which can freeze and destroy the cancer.  This procedure can be done under local anaesthetic or with a general anaesthetic. 

As this is a relatively new treatment much is still unknown about long term side effects.