Also known as cryosurgery or cryoablation, this option involves freezing the prostate to kill the cancer. Freeze probes are inserted into the prostate gland through the perineum (the space between the scrotum and the anus). Guided by ultrasound imaging, the tip of the probe is precisely positioned near the cancerous tissue and argon gas at -80 C is delivered to the prostate, literally freezing to death the prostate gland cells and any prostate cancer. Over the years, a number of modifications have been made utilizing ultrasound, urethral warming and temperature feedback to avoid freezing damage to the nearby structures. The treatment usually requires an overnight stay and is done in a single setting. It is minimally invasive and in general, patients retain very good urinary function. With whole gland freezing, erectile dysfunction is common; however, in certain circumstances, if the patient has a single, isolated area of cancer, only part of the prostate can be treated (focal cryotherapy). This greatly decreases the chance of erectile dysfunction or any other side effects. Patients who have had radiation therapy and have had the cancer return in the prostate are good candidates for salvage cryotherapy. In this circumstance, it is important to perform staging studies to assure that the cancer is confined to the prostate. This option gives some men another opportunity to have the cancer treated, be cured and to get off or not be treated with hormonal therapy.