| Cryotherapy
What is Cryotherapy? Back to Top
Cryotherapy, also called
cryosurgery, cryoablation or targeted cryoablation therapy, refers to
the application of extreme cold to destroy diseased tissue, including
cancer cells.
What are some common uses of the procedure? Back to Top
Since
the 1960s, cryotherapy has been used to destroy skin tumors,
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 tumors of the bone, brain, kidney, lung and spine. Researchers are
also evaluating its usefulness in freezing and shrinking benign breast
lumps, called fibroadenomas.
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.
How should I prepare for the procedure? Back to Top
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.
What does the equipment look like? Back to Top
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 ultrasound,
computed tomography (CT) or magnetic resonance (MR) images transmitted
to a monitor similar to a television screen.
How does the procedure work? Back to Top
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 apart
almost any cell.
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
tumors are repeatedly frozen and thawed.
Loss of blood supply.
Cells die when their blood supply is choked off by ice forming within
small tumor vessels, causing clotting. Since the average blood-clotting
time is approximately 10 minutes, the extreme cold is maintained for at
least 10 minutes unless tumor 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.
How is the procedure performed? Back to Top
For external
masses, liquid nitrogen is applied directly with a cotton swab or spray
device. For internal tumors, 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 tumor. 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 tumor. Likewise, for prostate cancer, six to eight
needle probes can be inserted through the perineum (the tissue between
the rectum and the scrotum/penis) and ultrasonically guided to freeze
the cancer.
What will I experience during the procedure? Back to Top
Intraoperative
cryotherapy procedures, such as for the liver or kidney, require
general anesthesia since the abdomen is opened through an incision or
air is pumped into the abdomen for a laparoscopy, an examination that
uses an illuminated tube. You would be unconscious for the entire
procedure and monitored by an anesthesiologist.
Percutaneous (through the skin) cryotherapy can be done with the
patient fully conscious by using only local anesthesia. Xylocaine or a
similar medication is injected throughout the tissues overlying the
tumor 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 a similar medication. Other than
the administration of the local anesthesia, 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.
Who interprets the results and how do I get them? Back to Top
Generally,
patients undergo cryotherapy 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 (done 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
interventional radiologists at some medical centers may also perform
this procedure.
The person treating you will determine the results of the procedure
and will speak to you and/or 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.
What are the benefits vs. risks? Back to Top
Benefits
- For intraoperative cryotherapy of kidney or liver tumors,
recovery time is usually much less than for major surgical removal of
the tumor.
- 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. Unlike heat-based treatments such as
radiofrequency, cryotherapy causes minimal pain after the procedure and
overnight stays for pain control are usually 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 fibroadenomas,
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:
- 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 in the bowel, which may release
bowel contents into the abdomen and can lead to infection.
- Treatment of lung tumors can cause the lung to collapse and fluid to accumulate around the lung.
Care
must be taken anywhere nerves are near the tumor. 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 anesthesia, 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.
What are the limitations of Cryotherapy? Back to Top
Cryotherapy
is an alternative cancer treatment when surgical removal of a tumor 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 tumors 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. Although there is
general U.S. Food and Drug Administration (FDA) approval, the
experience with cryotherapy is still early and most physicians reserve
it for patients who are not good candidates for other cancer treatments. Back to Top
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