In cryosurgery, liquid nitrogen is used to destroy abnormal tissue. It is commonly used to treat tumors or precancerous lesions on the skin. The boiling point of nitrogen is 77°K (-320°F or -196°C). This extremely low temperature freezes cells on contact, destroying them. The amount of liquid nitrogen applied controls the depth of tissue destroyed. Liquid argon may also be used as a cooling agent.
Cryosurgery may also be performed internally through an incision. A special cryoprobe is cooled with liquid nitrogen and applied to specific locations. Imaging techniques such as ultrasound or CT are used to direct the surgery.
The extreme cold of cryosurgery will also cause damage to surrounding tissues. When used to treat cancer, the goal is to destroy all of the cancer cells while minimizing damage to healthy cells. Localized tissue damage can be problematic when it damages nearby vessels or nerves. Despite these risks, cryosurgery is considered lower risk than surgery or radiation for certain cancers.
