Cryotherapy is a technique that uses an extremely cold liquid or instrument to freeze and destroy abnormal 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. The technique is also known as cryocautery or cryosurgery.
Cryotherapy is used to destroy a variety of benign skin growths, such as warts, pre-cancerous lesions (actinic keratoses), and malignant lesions (basal cell and squamous cell cancers). It has been used at several medical centers for tumors of the prostate, liver, lung, breast, and brain as well as for cataracts, gynecological problems, and other diseases. The goal of cryotherapy is to freeze and destroy targeted skin growths while preserving the surrounding skin from injury.
In dermatology applications, there are three main techniques used in cryotherapy. In the simplest technique, usually reserved for warts and other benign skin growths, the physician dips a cotton swab or other applicator into a cup containing a "cryogen" such as liquid nitrogen and applies 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 approach, a device is used to direct a small spray of liquid nitrogen or other cryogen directly onto the skin growth. Freezing may last from five to 20 seconds, depending on the size of the lesion. A second freeze-thaw cycle may be required. Sometimes, the physician inserts a small needle connected to a thermometer into the lesion to make certain the lesion is cooled to a temperature low enough to guarantee maximum destruction. 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 skin lesion to freeze it. The freeze time can take two to three times longer than with the spray technique.
When used for cancer treatment, cryotherapy is usually performed as follows: for external tumors, liquid nitrogen is applied directly to the cancer cells with a cotton swab or spraying device; for internal tumors, liquid nitrogen is circulated through an instrument called a cryoprobe that is placed in contact with the tumor. To guide the cryoprobe and to monitor the freezing of the cells, the treating physician uses ultrasound to guide his work and spare nearby healthy tissue.
No extensive preparation is required prior to cryotherapy. 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. In dermatology applications, 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. In the case of cervical cryotherapy , the procedure is not performed during, or from two to three days before, the menstrual period.
In dermatology applications, redness, swelling, and the formation of a blister at the site of cryotherapy are all expected results of the treatment. A gauze dressing is applied, and patients should wash the site three or four times daily while fluid continues to ooze from the wound, usually for five to 14 days. A dry crust will form that falls off by itself. Wounds on the head and neck may take four to six weeks to heal, but those on the body, arms, and legs can take longer. Some patients experience pain at the site following the treatment. This can usually be eased with acetaminophen (Tylenol), though in some cases a stronger pain reliever may be required.
In dermatology applications, 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 to underlying skin and tissue. These risks are generally minimal in the hands of experienced physicians.
Care should be taken, however, in subjecting people with diabetes or certain circulation problems to cryotherapy for growths located on their lower legs, ankles, and feet. In these patients, healing can be poor and the risk of infection can be higher than for other patients.
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, particularly in areas where they lie closer to the surface of the skin, such as the fingers, the wrist, and the area behind the ear. Reports suggest this will disappear within several months.
In cancer treatment, cryosurgery does have side effects, although they may be less severe than those associated with conventional surgery or radiation therapy. Cryosurgery of the liver may cause damage to the bile ducts or major blood vessels, which can lead to heavy bleeding or infection. Cryosurgery for prostate cancer may affect the urinary system. It also may cause incontinence (lack of control over urine flow) and impotence (loss of sexual function), although these side effects are often temporary. Cryosurgery for cervical tumors has not been shown to affect fertility, but this possibility is under study. More studies must be conducted to determine the long-term effects of cryosurgery as a cancer treatment approach.
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, while 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.
Alternatives to cryotherapy depend on the specific medical condition being treated. A general alternative is the use of conventional surgical procedures.
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Lynch, Peter J., and W. Mitchell Sams Jr. Principles and Practice of Dermatology, 2nd ed. New York: Churchill Livingstone, 1996.
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American Academy of Dermatology. 930 N. Meacham Road, P.O. Box 4014, Schaumburg, IL 60168-4014. (847) 330-0230. Fax: (847) 330-0050. http://www.aad.org .
American Society for Dermatologic Surgery. 930 N. Meacham Road, PO Box 4014, Schaumburg, IL 60168-4014. (847) 330-9830. http://www.asds-net.org .
"Cryotherapy." Family Practice Notebook. http://www.fpnotebook.com/DER233.htm. .
Richard H. Camer
Monique Laberge, PhD
WHO PERFORMS THE PROCEDURE AND WHERE IS IT PERFORMED?
Cryotherapy is performed by the treating physician, who may be a gynecologist (cervical cryotherapy) or a dermatologist (wart removal) or an oncologist ( tumor removal ). The procedure is usually carried out on an outpatient basis, but may require a hospital setting depending on the condition requiring the cryotherapy.
QUESTIONS TO ASK THE DOCTOR
- What happens on the day of surgery?
- What type of anesthesia will be used?
- What will I feel during cryotherapy?
- What happens after cryotherapy?
- What are the risks associated with cryotherapy?
- How is cryotherapy done?
- Will there be a scar?