What
is the prostate and where is it?
The prostate is a small gland, about the size
of a walnut, which lies just below the bladder. The tube draining
the bladder, called the urethra, passes through the center of the
gland, to the penis.
Valve
mechanisms, also called sphincters, maintain continence and stop
urine leaking out of the bladder. They are located just above and
below the prostate gland. The one above, is incorporated into the
bladder tissues. The one below, the sphincter, tends to be more
important.
What does the prostate do?
The prostate gland is a part of the male
reproductive system. It develops at puberty and continues to enlarge
throughout life.
The
prostate acts rather like a junction box. It allows the tubes that
transport sperm from each testicle and the tubes that drain from
the seminal vesicles to meet and then empty their contents into
the urethra. The seminal vesicles consistent of two pouches that
provide nutrients for the sperm and lie immediately behind the prostate.
At
the point of orgasm , sperm, seminal vesicle fluid and prostatic
secretions enter the urethra and mix together, forming semen. This
is then ejaculated out through the penis by rhythmic muscular contractions.
What controls the prostate gland?
The growth of the prostate is controlled
by testoserone, the male sex hormone. Most testosterone is made
by the testicles, although a small amount is also made by the adrenal
glands, which lie on top of each kidney. The hormone goes into the
bloodstream and finds its way to the prostate. Here, it is changed
into dihydro-testosterone (DHT), a more active form that stimulates
growth of the gland. The prostate gradually enlarges with ageing,
resulting in symptoms such as reduced urine flow and a feeling of
incomplete emptying of the bladder having passed urine. This enlargement
is usually benign (non-cancerous).
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Why does Prostate Cancer occur?
The real answer to this question is not known.
Nevertheless, here are a number of factors that can increase the
chance of developing prostate cancer. Relatives of patients with
prostate cancer have an increased risk of developing the disease
themselves, especially if their father or brother were affected.
There also appears to be a link with people living in urban areas
exposed to pollution and those consuming large quantity of dietary
fat.
What are the symptoms of Prostate Cancer?
There
are often no symptoms associated with early stage prostate cancer.
As the disease progresses and the tumour enlarges, it may press
on the urethra, which runs through the gland and obstruct the flow
of urine during urination. In this situation, the patient may notice
a weak, interrupted stream of urine that requires much straining,
and on completion he may sill feel that the bladder is not empty.
However, these symptoms are not specific to prostate cancer and
are most commonly found in benign (non-cancerous) enlargements of
the gland.
Blood in the semen may be a sign of prostate cancer, although again
this is a common finding and not normally related to malignancy.
If the tumour is spread to the bones, it may cause pain. The spine
is the most common site for this to occur.
What treats prostate cancer patients ?
This is the job of a specialist doctor, an
Urologist. Usually following an examination by the patient's General
Physician refers the patient to the Urologist so that a full range
of tests can be carried out and an assessment of the tumour made.
How is prostate cancer diagnosed ?
The doctor will initially ask the patient
questions to check their general medical health and see If they
are experiencing any symptoms associated with prostate cancer. Having
made a general examination, the doctor will then need to perform
a rectal examination to the feel of gland. A gloved, lubricated
finger is inserted into the rectum to check the size and the shape
of the prostate gland.
Blood Test
The prostate can be evaluated by
testing for the level of a particular protein in the blood called
PSA (Prostate Specific Antigen). Prostate enlargement tends to cause
an increase in the level of PSA, with malignant tumours producing
a greater increase than benign enlargements. However, other conditions
can also cause PSA to rise, such as a urinary infection. Therefore,
although a slight elevation in the PSA may indicate prostate cancer.
But it is by no means definite.
Ultrasound Examination and Biopsy
The Prostate can be imaged with ultrasound,
a device often used to scan pregnant women. To visualize the prostate,
a well lubricated probe, similar in size to a finger, is inserted
into the rectum, and images of the prostate appear on a screen.
The technique also provides pictures of seminal vesicles and the
tissues surrounding the gland. The images produced help to identify
areas within the gland that may be malignant, but the only way to
prove there is cancer present is to take a biopsy. A small piece
of tissue obtained by a special needle.
If a biopsy is to be performed at the time of the ultrasound scan,
the patient will be forewarned. A small needle is inserted alongside
the ultrasound probe, which can be moved to the area of the gland
in question. The procedure is no more painful than giving blood,
but may occasionally cause a momentary shooting pain in the base
of the penis. The doctor will usually give the patient an antibiotic
to help prevent any infection occurring.
Between 2-6 biopsies are normally taken, which are then analysed
in the laboratory and a diagnosis obtained. After the procedure,
it is quite common for the patient to see some blood in his urine,
semen and stools, but this usually settles over a week or two.
Other Tests
Two other types of scanning machines are available.
A computer tomography (CT) scan or a magnetic resonance imaging
(MRI) scan are sometimes used to obtain pictures of the prostate
and the surrounding tissue. Both are painless. The CT scanner uses
X-Rays and MRI uses magnetic fields to produce their images.
Stages and Grade of Prostate Cancer
1. The earliest stage, where the cancer is so
small that it cannot be felt on rectal examination, but is discovered
in a prostate biopsy, or in a prostate tissue that has been surgically
removed to unblock the flow of urine (as is a transurethral resection
of the prostate - TURP).
2. The tumour can now be felt on rectal examination,
but is still confined to the prostate gland and has not spread.
3. The tumour has spread outside the gland and may have invaded the
seminal vesicles.
4. The tumour has spread to involve other
surrounding tissues such as rectum, bladder or muscles of the pelvis.
Bone Scan
Once a diagnosis of prostate cancer
has been made, if spread is suspected usually by the level of PSA,
a bone scan can be used to see if the tumour has invaded bone. For
this painless test, a tiny, harmless quantity of radioactive agent
is injected into a vein. This makes its way to any cancer deposits
within the skeleton and sticks to them. After a few hours, the patient
is scanned by a special camera, similar to an X-ray machine, which
detects these deposits, if present.
How is prostate cancer treated?
At present, there is no definite
evidence as to which is the best treatment for prostate cancer,
especially for early stage 1 or 2 tumours, and different urologists
may have differing views. One of the reasons for this is that many
patients with early stage disease will often live 10 years or more
if no treatment at all is used - therefore, more involved therapies
have a hard act to beat. However, in other patients, the disease
can be much more serious. Unfortunately, whilst it is possible to
give broad figures, it can be difficult to predict what course the
prostate cancer will take in any individual.
Also, the side effects of treatment, which can be severe, must be
balanced against the overall benefit of therapy. For example, there
is little point in undergoing major surgery to take out the prostate
if the tumour has spread to areas where it cannot be removed.
The treatment of prostate cancer is determined by the stage and,
to a lesser extent, the grade of the disease. There are a number
of treatment options for every stage, each with their own advantages
and disadvantages. Thus, the therapy needs to be tailored to suit
each individual patient. It is possible to cure patients with prostate
cancer at an early stage, but even if cure is not a possibility,
the disease can normally be kept in check for a number of years.
What are the treatment options in prostate
cancer?
The different treatment options
available to patients diagnosed with prostate cancer are described
below. It is important that any patient with such a diagnosis is
aware of the different treatments, and they should feel free to
discuss these with their Urologist. Whatever therapy is undertaken
the patient will need regular follow-up examinations, which may
involve a PSA blood test and scans or x-rays, for a number of years.
Careful Surveillance
If the cancer has been discovered accidentally,
during an operation to remove prostatic tissue blocking the urinary
stream, or by a PSA blood test and biopsy, and the patient has no
symptoms, "wait and see" policy may be chosen. This does not mean,
"do nothing", but the patient will be regularly monitored by the
doctor and if problems develop, appropriate action taken. These
actions will often involve the use of hormone therapy, and on such
a regime patients commonly live for many years. This choice is most
frequently made by those patients with low grade disease specially
if elderly.
Prostatic Surgery
A radial prostatectomy is an operation
to remove the entire prostate and seminal vesicles. This operation
can be performed through an incision in the lower abdomen or through
an incision made between the anus and scrotum.
These are complex and major operations that usually require a hospital
stay about one week. Such procedures should mot be confused with
conventional prostate tissue blocking the urinary flow is removed,
leaving part of the gland behind.
The advantage of surgery is that it is one off procedure and provided
the cancer is confined to the prostate, will hopefully cure the
disease. It avoids side effects of radiotherapy and is thought by
some to be the most effective form of treatment for early prostatic
cancer.
However, these are risks associated with radical prostatectomy.
It is a major operation, and involves a number of week's convalescence
to make a full recovery. Unfortunately, the prostate lies very close
to both the sphincters that control urinary continence and the nerves
that produce penile erection. In the past, removal of the gland
often caused damage to these structures, resulting in postoperative
urinary incontinence and impotence. Newer surgical techniques have
reduced the occurrence of impotence, and severe incontinence is
now uncommon. Furthermore, there are a number of new therapies to
treat such side effects, should they occur.
Radiotherapy
Radiotherapy involves high energy easy at
tumour, which aims to destroy the cancerous cells and leave the
healthy ones intact. It is a painless procedure, like having an
X-ray, although there can be troublesome aide effects associated
with the treatment. It may be used in two situations:
1. to treat early cancers confined to
the gland or the surrounding tissues and
2. to treat tumours that have spread to the bone and which are causing
pain. Radical radiotherapy for a tumour localized to the prostate
may be given in two ways. Conventionally, the rays are directed
by a machine through the body into the prostate, as with an x-ray.
The treatment is given on an out patient basis for five days a week
for 4 - 6 weeks. However, when Radiotherapy is being used to treat
the bones, only a few treatments are necessary.
Radiotherapy can also be given using radioactive seeds that are
approximately half the size of a grain of rice. These seeds, typically
80-100 in number, are inserted through needles which are passed
through the skin behind the scrotum and in front of the anus, then
into the prostate. The procedure is performed under an anesthetic.
It has the advantage of being either a day case or overnight stay
procedure, with patients rapidly returning to normal activities.
The side effects of radiotherapy are normally limited to patients
having radical treatment. But conventional radiotherapy is more
lengthy than surgery and often causes tiredness, nausea, diarrhea,
frequent and painful urination as well as bleeding both in the stools
and urine, and local skin reactions.
The advantage of radical radiotherapy is that it can cure early
prostate cancer without the need of a major surgery. It seldom causes
loss of urinary control, and impotence is less common than with
surgery.
Chemotherapy
Chemotherapy is usually in tablet
form, involves powerful drugs to attack the cancer cells and try
to prevent them growing. It is a second line of defense for patient
with advanced stage prostate cancer that is no longer controlled
by hormonal therapy.
Hormone Therapy
When the cancer has spread beyond
the prostate, going to either the lymph nodes or bones, hormonal
therapy is effective at shrinking the tumour, and reducing the side
effects of the disease. It does not provide a cure, but may keep
the cancer in check for a number of years.
The prostate gland and prostate cancer are under the influence of
testosterone, the male sex hormone, which drives the tumour to grow
and spread. By blocking the body's production of testosterone or
blocking its action, the growth of the tumour may be greatly reduced.
There are number of techniques to administer such hormonal therapy.
But whatever technique is chosen, certain side effects are common,
such as hot flushes, a loss of sexual desire, impotence and occasionally
breast tenderness or rarely enlargement.
Surgery
The parts of the testicles that produce testosterone
may be surgically removed by a small operation, called "Orchidectomy"
that can be performed as a day case procedure. This has the advantage
of being a one off treatment that does not rely on the patients
remembering their medication and tends to cause less breast problems.
However, the operation is irreversible and men develop a high pitched
voice after such a procedure.
Injection Therapy
An
injection known as an "LHRH Analogue" is given once a month or every
three months and this has a similar effect to removing testicles,
but is reversible and does not involve surgery. Immediately after
this therapy medication is prescribed to avoid the side effects.
Antiandrogen Tablets
This therapy involves taking daily
tablets to block the action of testosterone. The drugs have dual
action - (1) they reduce the production of testosterone by the testicles,
(2) avoid side effects like hot flushes, breast tenderness and impotence.
However, Antiandrogen tablets can cause nausea and diarrhea. |