The use of cold temperatures in medicine has been around for thousands of years, dating back to the ancient Egyptians. Although initially used to alleviate pain and inflammation, the use of “cold” has been extended to cancer therapy (specifically used to cause severe tissue damage). Cryotherapy refers to the therapeutic use of cold against pain and inflammation, while cryosurgery is defined as the “controlled use of substances that produce freezing temperatures cold enough to damage tissue severely.” Cryogens are the substances used to create the freezing temperatures that cause tissue damage. Examples of cryogens include liquid nitrogen and liquid nitrogen substitutes.

The freezing of tissue begins at 0ºC with the crystallization of water in the spaces between cells. Freezing tissue can be achieved either through a slow or rapid freeze, with thawing of tissue following suit. Cryosurgery utilizes both the rate of freeze as well as the rate of thaw. The optimal combination to treat malignant tumors being rapid freeze, slow thaw, followed by consecutive freeze–thaw cycles.

Cryogens may be applied by use of a probe, or by pouring the liquid directly on the targeted area. Devices such as cryocones should be used to ensure the cryogen stays within the treatment area.

Cryosurgery is ideal for small tumors of the skin, oral cavity, and anus. Advantages include lack of hemorrhage, lack of systemic effects from freezing, and ease of repetition. Disadvantages include sloughing of skin, scar formation, as well as weakened bone, and rapid degranulation of mast cell tumors.