What is Cryotherapy?

Cryotherapy, also called cryosurgery, cryoablation or targeted cryoablation therapy, refers to the application of extreme cold to destroy diseased tissue, including cancer cells.

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What are some common uses of the procedure?

Since the 1960s, cryotherapy has been used to destroy skin tumours, precancerous skin moles, nodules, skin tags or unsightly freckles. It also has been used to destroy retinoblastomas, a childhood cancer of the retina. With the improvement of imaging techniques and the development of devices to better control extreme temperatures, physicians have begun to perform cryotherapy for prostate, liver, and cervical cancer, especially if surgery is not possible. Currently, research is being done to determine the effectiveness of cryotherapy for tumours of the bone, brain, kidney, lung and spine. Researchers are also evaluating its usefulness in freezing and shrinking benign breast lumps, called fibro adenomas.

Some medical professionals, particularly those who specialize in sports medicine, use the term cryotherapy to refer to the application of cold to muscles and joints that are sore or fatigued after physical exertion. However, this is not related to the radiologic-based technique described here.
 

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How should I prepare for the procedure?

No special preparation is needed to undergo cryotherapy, although some physicians recommend ibuprofen (400 mg) a half hour before the procedure to relieve minor discomfort. Establishment of an intravenous line provides access for additional sedation drugs. Any potential bleeding problems will usually have been identified in advance by blood tests. Some physicians administer a dose of antibiotics before cryotherapy as a way to guard against infection.
 

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What does the equipment look like?

Cryotherapy is carried out by using a cryoprobe, a thin wand-like device with a handle or trigger or a series of small needles, attached via tubing to a source of nitrogen or argon, which super-cools the probe tip. Most cryotherapy units use argon gas and are approved by the U.S. Food and Drug Administration (FDA) for general urologic and oncologic uses. The cryoprobe is placed in the proper position using imaging guidance, and as internal tissue is being frozen, the physician avoids damaging healthy tissue by viewing the movement of the probe on live ultrasound, computed tomography (CT), or magnetic resonance (MR) images transmitted to a monitor similar to a television screen.
 

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How does the procedure work?

Living tissue, healthy or diseased, cannot withstand extremely cold conditions and dies from:

• Ice within the cell. At approximately -40°C (-40°F) or less, intracellular lethal-ice crystals begin to form that will tear almost any cell apart.
• Bursting from swelling or shrinking. If ice forms only outside the cell, osmosis—the movement of a solution through the membrane of a cell—causes the cell to shrink as it gives up water to replace the water that has turned to ice. Then, as the area thaws, water rushes into the shrunken cell and causes it to burst. For this reason, cryotherapy usually consists of a series of steps in which tumours are repeatedly frozen and thawed.
• Loss of blood supply. Cells die when their blood supply is choked off by ice forming within small tumour vessels, causing clotting. Since the average blood-clotting time is approximately 10 minutes, the extreme cold is maintained for at least 10 minutes unless tumour temperatures indicate that lethal-ice temperatures have been reached.

Once the cells are destroyed, components of the immune system, primarily the white blood cells, clear out the dead tissue. There is some evidence to suggest that this procedure also stimulates the immune system to attack remaining cancer cells.
 

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How is the procedure performed?

For external masses, liquid nitrogen is applied directly with a cotton swab or spray device. For internal tumours, liquid nitrogen or argon gas is circulated through the cryoprobe, which comes into contact with the diseased tissue.

More advanced forms of cryotherapy, such as for treatment of liver cancer, involve the insertion of the probe through an incision or threaded through the skin. Then, by using an imaging device such as ultrasound or computed tomography (CT), the physician targets and freezes the tumour. For lung cancer, the probe is passed through a bronchoscope, an instrument used to examine the trachea and bronchi, and placed on the abnormal tissue, or several straw-thin cryoprobes are inserted through a tiny skin incision and guided by computed tomography (CT) to the lung tumour. Likewise, for prostate cancer, six to eight needle probes can be inserted through the perineum (between the rectum and pubic areas) and ultrasonically guided to freeze the cancer.

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What will I experience during the procedure?

Intraoperative cryotherapy procedures, such as for the liver or kidney, require general anaesthesia since the abdomen is opened through an incision or air is pumped into the abdomen for a laparoscopy, an examination using an illuminated tube. You would be unconscious for the entire procedure and monitored by an anaesthesiologist.

Percutaneous (through the skin) cryotherapy can be done with the patient fully conscious by using only local anaesthesia. Xylocaine or a similar medication is injected throughout the tissues overlying the tumour where the probes go through. You may feel a brief pinch and burning sensation during the injection, much like when a dentist administers procaine (Novocaine) or another similar medication. Other than the administration of the local anaesthesia, the most common discomfort is having to be still for up to two hours. Intravenous sedation can be given to help patients relax while on the table for computed tomography (CT) or magnetic resonance (MR) imaging. Patients with joint discomforts may require intravenously administered sedation to hold still.
 

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Who interprets the results and how do I get them?

Generally, patients undergo cryotherapy either because a referring physician has recommended it or a cancer specialist, after analyzing the patient's condition and all available medical history, has decided it is the best way to treat the cancer.

• The performance of intraoperative cryotherapy that performed during surgery, requires the combined skills of a cancer surgeon and an interventional radiologist.
• The performance of percutaneous cryotherapy requires only an interventional radiologist since the procedure is done in the radiology department, rather than the operating room. Cryotherapy devices, which are 2-3 mm (about one-tenth of an inch) in diameter, are inserted through skin incisions. This is done by using ultrasound, computed tomography (CT), or magnetic resonance (MR) imaging to determine the position of the devices.
• Prostate cryotherapy is usually performed by a urologist, but experienced radiologists at some medical centers may also perform this procedure.

Your cancer specialist will determine the results of the procedure and send the results to your referring physician. It may take a few more weeks for the cancer specialist to determine the extent of treatment success. Once known, this information will also be sent to your referring physician, who will give the information to you.

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What are the benefits vs. risks?

Benefits

• For intraoperative cryotherapy of kidney or liver tumours, recovery time is usually much less than for major surgical removal of the tumour. Patients are usually discharged from the hospital in less than half the time needed to recover from major surgery.
• For percutaneous cryotherapy, the patient may stay overnight or be released several hours after the procedure. In contrast to heat-based treatments, such as radiofrequency, cryotherapy causes minimal pain after the procedure, and overnight stays for pain control are not needed. Therefore, cryotherapy has great potential to evolve into an outpatient procedure.
• Percutaneous cryotherapy is less traumatic than open surgery since only a small incision is needed to pass the probe through the skin, which limits damage to healthy tissue. Consequently, percutaneous cryotherapy is less costly and results in fewer side effects than open surgery. A patient usually can resume activities of daily living 24 hours after the procedure, if not sooner. However, caution about heavy lifting may extend for several days after abdominal treatment.
• For treatment of fibro adenomas, cryotherapy causes minimal scar tissue and no apparent calcifications. Consequently, screening mammography can continue to be carried out without the potential for calcifications being misidentified as breast disease.

Risks

Some minimal risks pertain to specific cryotherapy procedures, however:

• Treatment of the liver can damage bile ducts or cause heavy bleeding. If the freeze is near the diaphragm, fluid can accumulate in the space around the lungs.
• Treatment of the kidney can damage the urine-collecting systems or cause heavy bleeding.
• Any treatment of the abdomen needs to be carried out carefully around the bowel since damage may cause a hole, which may release stool into the abdomen and can lead to infection.
• Treatment of lung tumours can cause the lung to collapse and fluid to accumulate around the lung.
• Care must be taken anywhere nerves are near the tumour. Completely frozen nerves can cause motor weakness or numbness in the area supplied by the nerves.

Cryotherapy may be more complicated for prostate cancer, and:

• Usually requires a short hospital stay.
• May cause permanent impotence since nerves controlling sexual potency are commonly involved in the freezing process. However, nerves can regenerate, resolving the problem in some patients.
• While the patient is under anaesthesia, a bladder tube is positioned to drain urine until the swelling of the bladder neck - as a result of the procedure - resolves.
• May cause urethral sloughing; that is, blocking of the urine stream with dead tissue. Sloughing is reduced by keeping the urethra warm with sterile water circulating continuously through a catheter placed in the urethra during the procedure.

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What are the limitations of Cryotherapy?

Cryotherapy is an alternative cancer treatment when surgical removal of a tumour may be difficult or, for some patients, impossible. But its long-term effectiveness is still being examined. Currently, little published data deal with the results of percutaneous cryotherapy, but seven-year follow-up for prostate cancer suggests cancer-control rates are similar to surgery or radiation therapy.

• Cryotherapy is considered a localized therapy. It can only treat disease at a single site. It cannot treat cancer that has spread to other parts of the body.
• Because physicians treat the tumours they see on radiologic images, microscopic cancer can be missed.
• Although its use in the bone, kidneys, liver and lung is promising, cryotherapy may be considered experimental; consequently, many medical insurance companies will not pay for the procedure. Despite general U.S. Food and Drug Administration (FDA) approval, early experience with cryotherapy makes most physicians reserve it for patients who are not good candidates for other cancer treatments.

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