Cryotherapy is a technique that uses an extremely cold liquid or instruments to freeze and destroy abnormal or cancerous skin cells that require removal. The technique has been in use since the turn of the century, but modern techniques have made it widely available to dermatologists and primary care doctors. Recent advances have also lead to more use of cryotherapy in treating internal cancer. The technique is also called cryosurgery.
Cryotherapy can be employed to destroy a variety of benign skin growths, such as warts, precancerous lesions (such as actinic keratoses), and malignant lesions (such as basal cell and squamous cell cancers). It has also found new use in treating internal cancers, such as cancers of the prostate gland and the breast. The goal of cryotherapy is to freeze and destroy targeted skin growths or cancers while preserving the surrounding tissue from injury.
Cryotherapy is not recommended for certain areas of the body because of the danger of destruction of normal
If it remains unclear whether a growth is benign or malignant, a sample of tissue should be removed for analysis (biopsy) by a pathologist before any attempts to destroy the lesion with cryotherapy. Care should be taken in people with diabetes or certain circulation problems when cryotherapy is considered for growths located on their lower legs, ankles, and feet. In these patients, healing can be poor and the risk of infection can be high.
There are three main techniques used to perform cryotherapy. In the simplest technique, usually reserved for warts and other benign skin growths, the physician will dip a cotton swab or other applicator into a cup containing a "cryogen, " such as liquid nitrogen, and apply it directly to the skin growth to freeze it. At a temperature of 320°F (-196°C), liquid nitrogen is the coldest cryogen available. The goal is to freeze the skin growth as quickly as possible, and then let it thaw slowly to cause maximum destruction of the skin cells. A second application may be necessary depending on the size of the growth.
In another cryotherapy technique, a device is used to direct a small spray of liquid nitrogen or other cryogen directly onto the skin growth. Freezing may last from 20-30 seconds, depending on the size of the lesion. A second freeze-thaw cycle may be required. In a third option, liquid nitrogen or another cryogen is circulated through a probe to cool it to low temperatures. The probe is then brought into direct contact with the lesion, either on the skin or in the case of internal cancers, inside the patient. The freeze time can take two to three times longer than with the spray technique.
Extensive preparation prior to cryotherapy is not required for external lesions. The area to be treated should be clean and dry, but sterile preparation is not necessary. Patients should know that they will experience some pain at the time of the freezing, but local anesthesia is usually not required. The physician may want to reduce the size of certain growths, such as warts, prior to the cryotherapy procedure, and may have patients apply salicylic acid preparations to the growth over several weeks. Sometimes, the physician will pare away some of the tissue using a device called a curette or a scalpel.
Preparation for treating cancers inside the body, such as prostate cancer, is slightly more complicated. The areas that are to be cooled are precisely mapped using ultrasound imaging or a specialized x-ray machine known as a computed axial tomography (CAT) scan. Temperature sensors are then placed inside and around the tumor to monitor the temperature. Lastly, cooling probes are then placed in and around the tumor.
Cryotherapy poses little risk and can be well tolerated by elderly and other patients who are not good candidates for other surgical procedures. As with other surgical procedures, there is some risk of scarring, infection, and damage
Some redness, swelling, blistering, and oozing of fluid are all common results of cryotherapy. Healing time can vary by the site treated and the cryotherapy technique used. When cryogen is applied directly to the growth, healing may occur in three weeks. Growths treated on the head and neck with the spray technique may take four to six weeks to heal; growths treated on other areas of the body may take considerably longer. Cryotherapy boasts high success rates in permanently removing skin growths; even for malignant lesions such as squamous cell and basal cell cancers, studies have shown a cure rate of up to 98%. For certain types of growths, such as some forms of warts, repeat treatments over several weeks are necessary to prevent the growth's return.
In the case of internal tumors, such as cancers of the prostate, cryotherapy has been shown to be at least as effective as other means, such as radiation therapy, with fewer side effects and faster recovery time.
Although cryotherapy is a relatively low risk procedure, some side effects may occur as a result of the treatment. They include:
- Infection. Though uncommon, infection is more likely on the lower legs where healing can take several months.
- Pigmentary changes. Both hypopigmentation (lightening of the skin) and hyperpigmentation (darkening of the skin) are possible after cryotherapy. Both generally last a few months, but can be longer lasting.
- Nerve damage. Though rare, damage to nerves is possible. Reports suggest this will disappear within several months.
Abeloff, Martin D., James O. Armitage, Allen S. Lichter, and John E. Niederhuber. Clinical Oncology. New York: Churchill Livingstone, 2000.
Baust, John, et al. "Minimally Invasive Cryosurgery-Techno-logical Advances." Cryobiology 34 (1997): 373-384.
Fintor, Lou. "Cancer Cryosurgery Potentially "Hot" For Patients, New Markets." Journal of the National Cancer Institute 92 (September 2000): 1464-1466.
American Academy of Dermatology. 930 N. Meacham Road, P.O. Box 4014, Schaumburg, IL 60168-4014. (847)330-0230. <http://www.aad.org>.
National Cancer Institute. <http://cis.nci.nih.gov>.
Edward R. Rosick, D.O., M.P.H.
Basal cell cancer
—A substance with a very low boiling point, such as liquid nitrogen, used in cryotherapy treatment.
—The most dangerous form of skin cancer. It should not be treated with cryotherapy but should be removed surgically instead.
Squamous cell cancer
—A form of skin cancer that usually originates in sun-damaged areas or preexisting lesions; at first local and superficial, it may later spread to other areas of the body.