Targeted cryoablation of the prostate involves needle probes being placed into the prostate and using argon gas to "superfreeze" the prostate tissue. Argon rapidly cools the probe tip to -187°C (-304.6°F) and can be rapidly exchanged with helium at 67°C (152.6°F) for an active thawing phase. Cryotherapy kills cancer by extracellular and intracellular ice crystal formation, intracellular dehydration and pH changes, ischemic necrosis via vascular injury by thrombosis of blood vessels.
As cryoablation is frequently associated with erectile dysfunction, only patients with pre-existing erectile dysfunction are candidates for cryoablation of the prostate. Patients serum prostate-specific antigen level ≤10 ng/mL, Gleason score ≤7, clinical stage ≤T2a are expected to have the best outcomes. Higher risk disease cancer (PSA greater than 10, Gleason score greater than 7, T2b disease) may be treated by cryoablation of the prostate but most be used with caution secondary to the risk of loco-regional/distant cancer spread. Cryoablation has also been used for local disease control in patients with known metastatic/androgen independant disease for palliation of local symptoms, i.e. hematuria or urinary obstruction.
Cryosurgery has recently been established as a viable alternative for patients in whom radiotherapy has failed. Tumor cells resistant to radiotherapy, androgen withdrawal and chemotherapy may remain vulnerable to the physical trauma of freezing and thawing. Most cases have been performed in patients whose after external-beam radiotherapy, but success has been achieved in patients after brachytherapy.
Cryosurgery is performed on an outpatient basis or for 24-hour observation.