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Patients who chose to undergo cryotherapy
as their prostate
cancer treatment will be in the hospital for one
or two days. The planning of the minimally invasive
surgery is done as part of the procedure. The patient
is placed under general anesthesia. The entire procedure
will take two or three hours. The patient is placed
in the exaggerated dorsal lithotomy position. This position
means that his legs are placed in stirrups, lifted to
a 90 degree angle, and opened, and that his perineum
is placed just over the edge of the operating table.
The dorsal lithotomy position gives the doctor a clear
view of the minimally invasive site. The patient is
shaved and cleaned from the perineum to the or navel.
The surgeon will then insert a catheter to distend the
bladder.
The surgeon will use the transrectal
ultrasound to obtain a picture of the
prostate gland and surrounding organs. A transperineal
needle template that will guide the cryoneedles is attached
to a stabilizing device and gently fixed against the
skin of the perineum. The TRUS
will use aiming grid software to guide the needles as
well and the template’s holes correspond with
this image.
The needles are inserted into three
or four horizontal layers with two to five needles per
layer. The number of cryoneedles depends on the size
of the patient’s prostate gland and the extent
of his prostate cancer. In prostate cryotherapy, the
third generation needles have made it possible to treat
the prostatic
capsule and the seminal
vesicles. As many as five thermocouples
will be inserted into the midgland of the prostate,
the urinary
sphincter, and each neurovascular
bundle. The thermocouple in the urinary
sphincter is usually kept above 15 degrees Celsius.
The ones in the midgland and the neurovascular bundles
are there to ensure the temperature of the prostate
gland reaches negative 40 degrees Celsius. Because the
neurovascular bundles are destroyed by this temperature,
cryotherapy may have a higher incidence of impotence.
After the needles have been positioned,
the catheter is removed and the doctor examines the
urethra
with a cystoscopy
for any misplacement. The doctor will reposition needles
if necessary. After this inspection, a warming catheter
is inserted into the urethra. A warm saline solution
is circulated through the bladder, which is kept nearly
full to protect it from the tip of the warming device.
Throughout the minimally invasive surgery, the urethra
and bladder are kept at 43 degrees Celsius.
Argon
gas is circulated through the tips of the cryoneedles.
The freezing gas creates ice balls on the tips of the
needles. Ice crystals form inside of or around the cells
and the pH level changes. These actions are what make
cryotherapy a viable prostate cancer treatment. Freezing
also may activate an anti-tumor response of the body,
which occurs when the body recognizes the tumor as an
invading agent and attacks the disease itself. The freeze
cycle lasts about 10 minutes or until the temperature
reaches negative 40 degrees Celsius. There are two types
of thawing processes. One is passive: the doctor allows
the relative temperature of the body to return the prostate
gland to normal temperature. The other is active: the
doctor circulates helium gas through the cryoneedles.
The helium speeds up the thawing process. Some researchers
believe however that the passive thaw process is more
effective is destroying the tumor, though slower for
the doctor. Patients should not be afraid to speak frankly
with their doctors about which procedure they would
prefer.
The freeze-thaw cycle is repeated
once or twice, depending on the policy of the center.
After the procedure, the warming catheter is left in
place for at least another five minutes to reduce the
risk of urethral sloughing. When the warming catheter
is removed, a urinary catheter is inserted in its place.
The new catheter will be removed in 2 or 3 days. Patients
are usually discharged the same day of the procedure.
Doctors will prescribe antibiotics and an alpha-blocker
which will relax the neck of bladder and decrease the
severity of urinary side effects. Patients can also
take pain-medication to combat the soreness of the perineum.
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