Brachytherapy Treatment Option
What is brachytherapy?
Brachy comes from the Greek root meaning short. Brachytherapy means that the
radiation travels a short distance into the tissues, whereas with an external
beam source the radiation must travel a long distance to reach its target
tissue. In essence with brachytherapy the source of radiation is implanted
directly into the tissue to be irradiated.
The oncologist can vary certain parameters:
The dose of the radiation by changing the number of seeds used or by charging
the seeds to a particular level of radiation.
The energy delivered to the tissues by changing the radioactive material.
The period of radiation by altering the radioactive isotope.
The field of radiation by the particular placement of seeds.
Different cancers respond to different
forms of radiation treatment. Oncologists have learnt through trial and error
what type of radiation is best for each particular cancer.
What types of brachytherapy
are available for prostate cancer?
There are basically two forms of
a) Low dose brachytherapy (LDR)
Low dose brachytherapy is the conventional
method whereby radioactive seeds are placed permanently into the prostate
gland. In prostate cancers the commonest seeds used are radioactive iodine or
palladium. These deliver a low dose of radiation over a period of several
months. After a certain time, determined by the isotope, they become inactive.
There has never been a report that these seeds can cause any harm over the long
term. The method by which the seeds are placed is critical and will be
discussed further on in the text.
b) High dose brachytherapy (HDR)
This treatment is not commonly used. It is
available only in certain academic institutions. In this form of treatment high
dose iridium rods are temporarily placed in the prostate gland for a few
minutes. The dose is repeated every six hours until four doses have been given.
This form of treatment is used in patients who for some technical reason cannot
have LDR therapy. Safety protocols are much more stringent because the
radiation is more dangerous. Also the treatment is far more involved
technically, requires expensive auxiliary equipment and additional trained
personnel. The treatment takes longer and additional external beam radiotherapy
has to be given as well.
How are the seeds placed?
In the early nineties a technique to
place seeds permanently in the prostate gland was developed. The patient would
have the prostate gland imaged carefully prior to the seed placement procedure.
The oncologist would then design a plan to place seeds in the prostate
according to its dimensions. The seeds would be ordered and the patient would
have his procedure about a week later. The patient went to theatre, was
anaesthetised and the seeds then inserted through the perineal area into the
prostate gland. However what was not well understood was the issue of prostate
mobility. Needles were inserted into the prostate gland without direct
visualisation of the gland. The needles were inserted according to the position
of the gland on the pre-plan scan. Inserting needles into a prostate gland can
change its shape and move it up to 20 mm in a headwise direction. The result
was that needles were now not positioned correctly and the seeds were therefore
placed in the wrong position. This led to damage to surrounding organs and cold
zones within the prostate gland. Side-effects where thus common including
serious side-effects. Cure rates were not excellent. Amazingly many centres
continue to use this technology.
The next major advance came with combining
the pre-planning stage with the actual seed implant. Again however the seed
placement was based on indirect visualisation of the prostate gland. The
position was inferred from x-ray imaging of the bladder base rather than direct
visualisation. A system designed by Stock and Stone of the USA improved the
method by introducing rectal imaging and visualising the needle insertion into
the prostate gland. Their system was commercialised but it falls short when it
comes to source insertion and again seeds are not placed accurately. Surgeons
who do salvage prostatectomies on patients treated with this technique report
that the seeds are very erratically placed. However hybrid techniques are
widely used and the world literature reports good results.
This is now the gold standard that units
offering brachytherapy should strive to master. Using this system, each seed is
visualised as it is placed and the position exactly matches the plan that the
surgeon set out to achieve. A system of checks and balances ensures that if a
seed is inadvertently placed incorrectly then the plan will adapt to reposition
other seeds so the radiation cover is uniform. The end result is a seed
placement as close as possible to the ideal treatment plan.
Who can have brachytherapy?
Brachytherapy is an alternative to
radical prostatectomy as the treatment of choice to cure patients with
localised prostate cancer. The latest twelve year published data show that
brachytherapy achieves excellent results comparable to surgery. Even radiation
oncologists will agree that external beam radiotherapy does not provide
equivalent results for long-term cure. Basically the same criteria as for
radical prostatectomy apply to the use of brachytherapy. There are some
technical differences which will be discussed. First and foremost the patient
must have localised disease. There is no point in treating a patient locally
when the horse has already bolted from the stable. The majority of patients
will not have any local symptoms and so a systemic form of treatment with
minimal or no side effects on urination should be rather given. Prostate glands
larger than 40 gm should ideally be shrunk prior to brachytherapy using a short
course of hormonal therapy over three months. With real time brachytherapy this
is no longer an essential requirement because the technique solves several
technical problems involving large glands. Patients with significant bladder
obstructive symptoms, clinical evidence of bladder obstruction or with large
prostate middle lobes should not have brachytherapy because of the high risk of
urinary retention. A TURP procedure can be done prior to brachytherapy to
relieve the obstruction if real time brachytherapy is going to be used. There
should be a period of eight weeks between treatments to allow the prostate
gland to heal. Also the TURP procedure should be minimal in extent otherwise
needle placement can become impossible. After a TURP a prostate must be
carefully examined to assess if brachytherapy is still possible and safe to
perform. Patients with disease more advanced than T2b have traditionally not
been considered good candidates for radical prostatectomy by careful surgeons.
However there is an evolving place for treating patients with t2c or even T3
disease with brachytherapy in combination with external beam therapy and
hormonal therapy. Age is still considered by many people to be important in the
type of treatment offered. Young people tend to have very aggressive disease
and it is strongly felt their glands should be removed. However now that twelve
year data reveal that radical prostatectomy and real time brachytherapy are
equivalent in outcomes this argument is no longer valid. It is safe for young
people with prostate cancer to have brachytherapy.
What are the Side-Effects?
Brachytherapy including real time
brachytherapy is not without side-effects. The majority of patients receiving
real time brachytherapy will experience minimal post treatment symptoms.
Side-effects that can be expected include:
a) Reduced urine flow due to swelling
of the gland in the first few months. All patients are put onto a medication to
counter this problem.
b) Increased urgency and frequency due to
radiation irritating the sensory nerves in that region.
c) Pelvic pain especially when seeds are
placed too laterally.
d) Urinary retention, fortunately not
common, is a nuisance to manage and can have a profound effect on the patient.
Many will improve once the prostate swelling resolves.
e) Loose frequent stools from rectal
f) Reduction in ejaculate volume with time
as the prostate gland fibroses.
g) Orgasmalgia: this is a medical
term denoting pain with orgasm; bloody semen (haematospermia); and reduced
intensity of orgasm occur fairly frequently. Orgasmalgia tends to subside after
the first year. Haematospermia resolves soon after the resumption of sexual
intercourse following brachytherapy. It may occur again later with radiation
changes occurring in prostatic blood vessels.
h) Accelerated loss of erectile function
compared with other ageing males who have not received radiotherapy. Figures of
between 52 to 76 % potency rates are reported at six years after treatment. It
would seem that patients who are going to get erectile dysfunction will already
be reporting this issue by twenty four months after the procedure. Older men
receiving the radiation tend to have a greater fall-off in erectile function.
The addition of hormonal therapy also increases the risk of erectile
dysfunction. Regular sexual stimulation after brachytherapy helps to prevent
i) Severe complications such as rectal
fistulas, urethral stricture, incontinence and penile irradiation are
associated with pre-planning techniques and over dose of radiation to the
How is Brachytherapy performed in our
The patient is anaesthetised and
placed in the lithotomy position and the rectum washed out. A catheter is
inserted into the bladder.
A sonar probe is placed inside the
rectum and the prostate gland is visualised.
The images are captured onto a computer and
a three dimensional model of the prostate gland constructed.
A template is mounted against the
perineal skin. Through this template needles will be inserted into the prostate
A plan is created to place seeds into the
prostate gland according to the size and shape of the gland.
Needles are inserted into the
prostate gland through the template.
The prostate being rubbery and mobile
alters shape and position. How much it changes varies from patient to
patient.The original plan is modified for the new shape and the seeds are then
The prostate is checked after seed
placement for any cold spots. If present they are implanted with additional
seeds. The procedure is then complete.
After waking up, the patient has a
CAT scan of the prostate gland and the catheter is removed. After passing urine
the patient is discharged.
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