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Prostate - some questions and answers
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Where is the prostate gland and
what are its functions?
The prostate is a small gland about 20 grammes in weight
and the size of a walnut, situated in the abdomen at the base
of the bladder and above the rectum (back passage). It partly
surrounds the urethra (the tube that carries urine from the
bladder to the outside) and the tubes that carry sperm from
the testes. Associated with the prostate are two other small
structures called seminal vesicles. Internally, the prostate
can be divided into an area around the urethra that produces
mucus, and an outer zone where the main prostatic glands are
situated, embedded in supporting tissue called the stroma.
The whole is surrounded by a sheet of smooth muscle and a
fibrous capsule. The muscle contracts during sexual arousal
and squeezes the prostatic fluids into the ejaculatory ducts
and urethra, where they pass through the prostate. These help
make the sperm swim, a process that is assisted by the secretions
of the seminal vesicles, which provide the sperm with extra
energy. Overall, this creates alkaline conditions and helps
to neutralise the natural acidity of the female vagina, thus
protecting the sperm.
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What diseases can affect the prostate
gland?
There are three main conditions that affect the prostate:
1. enlargement – medically called benign prostatic hyperplasia
or BPH (sometimes called benign prostatic hypertrophy, but
the meaning is the same). A very enlarged prostate will weigh
about 40-50 grammes.
2. prostate cancer, and
3. inflammation of the prostate (prostatitis), usually as
a result of urinary tract infections.
In this booklet, only the first two of these conditions will
be considered.
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How common is BPH?
Evidence of BPH in microscopic tissue samples suggests that
the condition is very common, reaching figures of about 50
per cent in men of 60 years of age and over 90 per cent by
the age of 80. However, these microscopic changes may not
result in clinical symptoms or in sufficient enlargement to
be felt (palpated) during examination by the rectal route
(digital rectal examination or DRE). In fact, by no means
all men with clinical symptoms of BPH have palpable lesions,
reaching only about 50 per cent even in men in their 80s.
The rate of enlargement slows down dramatically in the over
70s and treatment will not always be necessary, even if the
lesions can be clearly felt by the doctor.
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Is BPH inherited?
BPH appearing in younger men seems to run in families to
some extent. Their close relatives have up to a four-fold
higher risk of requiring an operation compared to other men.
Further, most men requiring this operation under the age of
60 have an inherited form of BPH, compared with 15 per cent
of those requiring it over the age of 65.
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Male anatomy showing the location and
structure of the prostate gland - click
for larger |
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Are there any risk factors for BPH?
The most important risk factor is age. Race and ethnic background
are much less significant in BPH compared to prostate cancer.
Some other medical conditions which affect male hormone levels
may also increase risk. For instance, men born without an
enzyme called 5-alpha reductase, which converts testosterone
into dihydrotestosterone (DHT), almost never get BPH, clearly
implicating DHT in the origins of BPH.
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Evidence of BPH using microscopic and macroscopic
criteria - click
for larger |
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What are the symptoms of an enlarged
prostate?
Because the prostate enlarges very slowly, the symptoms may
hardly be noticeable at first, but in time, there may be changes
in bodily habits. These may include some or all of the following:
- a delay before flow begins when trying to urinate (hesitancy)
- the speed of urine flow may be slow, may stop and start
and there may be dribbling at the end
- a desire to pass urine more often or with greater urgency
- a need to get up more than twice a night to go to the
toilet l a feeling that the bladder has not emptied completely
- in a few cases, there may be some incontinence.
- These symptoms, which arise because the urethra is squeezed
by the swelling tissue, can greatly reduce the quality of
life. They can also cause embarrassment, anxiety and worry
about possible cancer.
Many men are embarrassed by urinary symptoms and choose to
ignore them. This must be discouraged, because although much
of the enlarging tissue in BPH is glandular, the muscle in
the prostate also increases. Sometimes this can clamp the
urethra shut in times of stress or cold, greatly restricting
urine flow and potentially damaging the kidneys. Over a period
of time, the bladder may also thicken and become less flexible,
thus aggravating the symptoms. A complete blockage of urine
flow is a medical emergency and admission to hospital will
be required.
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What treatments are available for BPH?
If the diagnosis turns out to be BPH, the doctor has several
options for treatment. To help choose, a ‘decision tree’ will
be used to select the best approach. The options are:
- a wait-and-see approach,
- prescription of medicines, and
- surgical methods that ease the pressure on the urethra.
The choice of method will depend on age, the type and severity
of the symptoms, and the size of the enlarged gland. If the
problem is fairly minor, the doctor may recommend a wait-and-see
approach with regular check-ups, sometimes called ‘watchful
waiting’. If the symptoms are causing more problems, then
medicines may be used. If they are more troublesome still
or potentially serious, an operation may be appropriate.
Traditional operations for BPH include transurethral resection
of the prostate (TURP) and transurethral incision of the prostate
(TUIP). TURP is the commonest operation. It is carried out
under a general anaesthetic and takes about an hour. It involves
passing an instrument up the urethra and cutting out the central
part of the prostate, leaving a ring of tissue behind. TUIP
may be better for men with a small prostate. The operation
is quicker (about 15-20 minutes) and involves making small
cuts in the neck of the bladder and prostate which allows
the enlarged tissue to spring back, thus relieving the pressure.
In both operations, a catheter will be inserted for a day
or two to help drain urine. There may be some initial discomfort
but this quickly subsides and most people go home in three
to four days. Side effects, though not frequent, may occasionally
be serious and include urinary retention and incontinence.
In some men (more often with TURP than TUIP), semen may pass
back into the bladder at ejaculation (retrograde ejaculation).
This is harmless, but it is permanent. If the prostate is
very enlarged, an operation called retropubic prostatectomy
may be performed. Here a horizontal cut is made in the lower
abdominal wall through which the prostate is removed.
Several new surgical methods have also been developed recently.
These include the use of spring-like devices that can hold
the compressed urethra open (stents) and the destruction of
the unwanted tissue by high temperature, lasers, or high-intensity
focused ultrasound. These will not be discussed further here,
but a simple account of each method can be found in Prostatic
Diseases and Their Treatment, by Roger S Kirby, and in slightly
more detail in Fast Facts: Benign Prostatic Hyperplasia’ by
Roger S Kirby and John D McConnell, both published by the
Health Press, Oxford.
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What are the main types of medicines
used in BPH?
Two main types of medicines are prescribed for BPH:
- alpha-blockers and
- 5-alpha reductase inhibitors.
Both types of compound can ease symptoms and thus avoid the
need in some cases for an operation, and 5-alpha reductase
inhibitors in particular can cause the enlarged prostate to
shrink. The alpha-blockers currently available include alfuzosin
(Sanofi-Synthélabo), doxazosin and prazosin (Pfizer), indoramin
(SmithKline Beecham), tamsulosin (Yamanouchi), and terazosin
(Abbott). Only one 5-alpha reductase inhibitor, finasteride
(Merck, Sharp & Dohme) is currently available in the UK.
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Does BPH turn into prostate cancer?
No, the two conditions are quite separate. In childhood,
the prostate gland is very small, but begins to grow at puberty.
In the active reproductive years, its size in most men remains
fairly constant, but growth begins again after the age of
about 40. It is not understood why this second round of enlargement
takes place, but most men over the age of 60 have some enlargement
of the prostate. In itself, this is harmless – hence the term
‘benign’. The changes that occur in cancer of the prostate
are quite different in nature and have the potential to spread
outside the prostate to other parts of the body.
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Evidence of BPH using microscopic and macroscopic
criteria - click
for larger |
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Are the symptoms of prostate cancer
different from those of BPH?
Many of the symptoms in BPH and prostate cancer are the same.
However, in cancer, cells within the prostate begin to multiply
out of control, gradually destroying the internal structure
of the gland. As the bulk of the cancer increases, it may
press on the urethra and interfere with urine flow in much
the same way as in BPH. Thus, in very different ways, both
BPH and prostate cancer cause prostate tissue to increase
in bulk and produce the same symptoms. It is possible to have
both BPH and prostate cancer at the same time. This is why
it is important to go to your doctor early if symptoms persist:
cancer detected early can be treated much more effectively.
In most men, cancer develops without any of the above symptoms.
In such individuals, the first clue that something is wrong
might be a positive PSA blood test, or symptoms caused by
the cancer spreading outside the prostate and affecting other
organs. For example, there may be pain in the spine, hips
or ribs – a sign that the disease has entered the bone – which
may prompt a visit to the doctor without ever suspecting there
may be a prostate problem.
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How common is prostate cancer?
In Western Europe, cancer of the prostate is rare in men
under 50. From 60 onwards though, the incidence (the number
of new cases per year per 100,000 men) rises steeply. At age
65, the incidence is around 100 per 100,000, rising to almost
500 per 100,000 by the age of 80. In the UK, prostate cancer
is the second most common cancer in men, and in 1995 there
were 18,848 new cases recorded; over 10,000 men die of this
disease each year.
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Does prostate cancer affect people from
all parts of the world?
Prostate cancer affects people from all nations, but there
are marked differences in its incidence. For example, one
of the highest rates is found in black-skinned Americans (80
per 100,000) compared to about 24 per 100,000 men in England
and Wales. However, in many Asian countries (India, Japan,
China), the incidence is very low. In China, there are fewer
than 4 new cases per 100,000 per year. Recent research has
found that the biochemistry of the prostate gland is different
in some respects in men from countries with a low incidence
compared to those with a high incidence, indicating a possible
genetic involvement.
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Are there any other risk factors for
prostate cancer?
A risk factor is anything that might increase a person’s
chance of developing a particular kind of cancer. In prostate
cancer, the greatest risk factor is age itself, because the
cancer is rare under the age of 50. Many other possible risk
factors have been examined, but in most cases, the results
are not clear. Diet may be a factor, and trials are in progress
to see if dietary supplements can help reduce the risk. A
shortage of the element selenium may be implicated. Selenium
is found naturally in bread, cereals and pasta, but the amount
present may be influenced by the soil levels where the crops
are grown. Lycopene, the red pigment in tomatoes, may also
help protect against prostate cancer and is the subject of
research. To clarify the role of diet further, the Imperial
Cancer Research Fund is currently analysing data from a large
European study called EPIC.
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Is prostate cancer inherited?
This is under active investigation at the Cancer Research
Campaign and elsewhere. In a small number of families where
several related men develop prostate cancer, it is clear that
faulty genes are at least partly responsible. Oddly, one has
been shown to be a gene associated with breast cancer susceptibility,
called BRCA2, which increases prostate cancer risk by five
times. The usual role of this gene is to repair damage to
DNA that occurs during life. Hence, if the gene is faulty,
damaged DNA is not repaired and cancer can then result. In
cases where there is no obvious family pattern, it is thought
that genes that suppress tumour growth (tumour suppressor
genes or TSGs) are involved. The role of these genes has already
been shown in breast cancer and a form of skin cancer called
malignant melanoma.
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What is the PSA blood test?
The letters PSA stand for Prostate Specific Antigen, a protein
produced by the prostate gland, whose normal function is to
liquefy semen. A ‘normal’ PSA level in the blood is any value
up to 4 nanogrammes per millilitre (ng/ml), though there is
a gradual drift upwards in men in older age groups. In both
BPH and prostate cancer, some PSA leaks into the blood stream,
so a positive PSA test cannot distinguish BPH from prostate
cancer. In general, the higher the level of PSA, the more
there is a likelihood of cancer: 60 per cent of men with a
PSA level higher than 10ng/ml have cancer. A PSA value greater
than 10 to 20ng/ml is often indicative of tumour spread beyond
the capsule of the prostate, while a value of 40ng/ml or more
often signifies that the disease has spread (metastasised).
A recent development has shown that by relating the amount
of PSA to the size of the prostate gland (Tissue PSA or T-PSA),
a more accurate and predictive result can be obtained. This
is useful in monitoring the effect of some kinds of treatment.
However, the connection has not been completely confirmed,
and you can have high levels of PSA and not have cancer, or
you can have low levels and have cancer. Several other prostate
gland markers are also being researched and might eventually
replace the PSA test.
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The increased risk of developing type 2
diabetes with increase in body mass index - click
for larger
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Why is there no national screening
programme for prostate cancer?
With the availability of the PSA test, there has been much
debate about a national screening programme for men in a similar
way to the breast and cervical smear screens introduced for
women. However, even among medical experts there is no general
agreement about the value of such a test, and in 1997 an NHS
report concluded that routine screening for prostate cancer
was inappropriate. Some of the arguments that are heard are:
- Many elderly men (overall about 1.5 to 2.5 per cent of
those between 50 and 70 years of age) will have evidence of
early prostate cancer if screened. But because the tumour
is slow-growing, most will be unlikely ever to develop clinical
symptoms.
- In such men, detection will often cause unnecessary worry
for many years and may lead to treatment which is in itself
harmful and unwarranted.
- There is a high cost element in treating cancers which
may never pose a health risk to the individual.
- The PSA test has not yet been shown to be an absolutely
reliable marker of prostate cancer.
- The value of screening for prostate cancer in reducing
deaths has not been absolutely established.
Because of these factors, the Government has been unwilling
to introduce a national screening programme for prostate cancer,
though in some other countries such as the USA, the PSA test
is much more widely used. However, much encouragement can
be taken from the recent announcement by the Government that,
in co-operation with cancer charities, it is assessing the
feasibility of a large trial of the PSA test to include 150,000-200,000
men. This will assess the ability of the test to identify
prostate cancer and will run for 10 years.
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Can a doctor distinguish between BPH
and prostate cancer?
Neither a rectal examination nor a PSA test can separate
these two conditions with certainty. However, a significantly
enlarged prostate, especially if it feels uneven (called craggy),
or a high PSA value will alert the doctor to the need for
further tests by a specialist. These may include an ultrasound
scan. During this scan, small tissue samples called biopsies
will probably be taken for examination. If any abnormal cells
are found, their appearance will help distinguish between
BPH and cancer and determine the stage of any cancer that
might be present.
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Are other tests likely if cancer is
suspected?
Yes. You may be given an X-ray and a bone scan to check whether
there has been any tumour spread – though this is unlikely
until late in the disease. For the bone scan, you will be
given an injection containing a radioactive element such as
99mTechnetium. This collects in the bone in areas of active
blood flow where the tumour may be lodged. The scan will be
performed after several hours and will reveal ‘hot spots’
in the skeleton. If spread has occurred, you may also be given
a magnetic resonance imaging (MRI) scan or a computed tomography
(CT) scan to clarify further the size and extent of your tumour
or if one is present at all. All of these are painless procedures,
though the machines are noisy and some people find them claustrophobic.
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What is meant by ‘staging’ in prostate
cancer?
Prostate cancer begins as a very small cluster of abnormal
cells which multiply, often over many years, to a large size,
with the potential to invade healthy tissue and disrupt normal
bodily functions. To help describe how developed a cancer
is, doctors have devised a system called ‘staging’. In prostate
cancer, the stages are numbered T1 to T4, based on the following
criteria:
- Stage T1: Tumour is very small and has not spread outside
the prostate. There are usually no symptoms and the tumour
cannot be felt by rectal examination. T1 tumours are normally
detected by chance during a routine medical, by a positive
PSA test, or during a routine operation for BPH.
- Stage T2: Tumour still located within the prostate, but
has enlarged enough to be felt by rectal examination or
seen in ultrasound or other types of scan. A few people
at Stage 2 may have some spread (metastases) outside the
gland.
- Stage T3: A tumour which has spread to tissues immediately
outside the prostate. Over a half of patients at this stage
will have metastases.
- Stage T4: A tumour which has spread to other structures
in the lower abdomen such as the lymph glands, bladder,
and rectum.
- Later Stage Disease: This signifies a more advanced condition
in which the cancer has spread to distant organs such as
the bone, liver, lungs, etc.
By giving the tumour a stage, the doctor will be in a better
position to select the most suitable treatment for each individual.
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Annual incidence of new cases of prostate
cancer in different parts of the world - click
for larger
Bone metastases in advanced prostate cancer.
diagram of sites often affected- click
for larger
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What treatments are available for prostate
cancer?
The choice of treatment for prostate cancer will be influenced
by a wide range of factors. An important consideration is
the individual’s age and general state of health. A second
is the appearance of the tumour cells when examined under
a microscope. From this, it is possible to estimate how active
the tumour is and how likely it is to spread to other parts
of the body. A third factor is the stage of the tumour at
diagnosis.
- The doctor will weigh up all these factors and then discuss
the most suitable treatment options with the patient and
his family. These will include:
- ‘watchful waiting’ – monitoring the disease through regular
check-ups, but delaying treatment until the disease shows
signs of progressing or symptoms become too troublesome
- radical prostatectomy – an operation to remove the prostate
gland and the immediately surrounding associated organs,
such as the seminal vesicles
- external beam radiotherapy or external beam conformal
radiotherapy
- radiotherapy using radioactive ‘seeds’ of Iodine125 which
are permanently inserted into the prostate (brachytherapy)
- an operation to reduce male hormone production by removal
of one or both testicles (partial or complete orchidectomy)
- the use of medicines to suppress the production and action
of male sex hormones (testosterone and DHT)
- some combination of the above, or
- for more advanced cases, medicines to slow down the growth
of tumour cells or to control pain.
Age and health are especially important, because a frail
elderly man will find it harder to recover from a major operation
or radiation therapy than a younger, active individual. Also,
the side effects of the chosen treatment, such as incontinence
and impotence, will also need to be weighed carefully against
any possible benefits.
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Left: Simplified diagram of T1, T2, T3 and
T4 stages of prostate cancer - click
for larger |
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What are the main types of medicines
used in prostate cancer?
Several different types of medicine may be used for the treatment
of prostate cancer, depending on its stage. Medicines currently
available include:
- Compounds related to a brain hormone called LHRH which
indirectly stimulates testosterone production by the testes
(sometimes called GnRH, which is the same thing). These
medicines mimic LHRH and are referred to as LHRH agonists.
They include buserelin (Shire), goserelin (AstraZeneca),
leuprorelin (Wyeth), and triptorelin (Ipsen).
- Antiandrogens that block the activity of testosterone
and other male steroid hormones circulating in the blood.
These include the non-steroidal compounds bicalutamide (AstraZeneca)
and flutamide (Schering Plough), and a steroidal antiandrogen
called cyproterone acetate (Schering Health Care).
- Medicines that help control the side effects of the first
two groups, and
- Medicines for people whose cancer has become resistant
to hormone treatment and has started to grow again. These
include estramustine phosphate (Pharmacia) and several other
powerful medicines (some still experimental) which may be
used alone or in combination.
How these medicines work and a little more information about
them is given later in this booklet.
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The type of decision tree the doctor will
use to decide the best treatment for prostate cancer - click
for larger
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What kind of general information and
support is available for people with prostate problems?
To be told you have cancer of any kind is a traumatic and
frightening experience, and prostate cancer is no exception.
Many people will experience a period of shock while the news
sinks in and will often assume that the worst will happen.
These reactions are natural, but it is important that clear
explanations are given at this time, and that there is some
means for getting answers to the many questions that will
arise. It can also be very helpful if family and friends are
supportive. The answers can be provided by the doctor or specialist,
but such people are often very busy and may not be available
when wanted. Fortunately, there are several booklets available
which will answer many of the most immediate questions:
- Understanding Cancer of the Prostate, available from CancerBACUP.
- Understanding Prostate Disorders, by Professor David Kirk,
published by the British Medical Association in the Family
Doctor series [ISBN 1-898205-14-0]. It is available from
bookshops and stores such as Boots the Chemist.
- The Treatment of Prostate Cancer: Questions and Answers,
published by the Covent Garden Cancer Research Trust and
the Royal College of Surgeons.
- Prostate Cancer: everything you need to know, available
from The Prostate Cancer Charity.
- Prostatic Diseases and their Treatments, by Roger S Kirby,
published by the Health Press Ltd, Elizabeth House, Queen
Street, Abingdon, Oxford, OX14 3JR, [ISBN 1-899541-63-2].
This has especially useful diagrams and descriptions of
the many non-medicines techniques used in BPH and prostate
cancer treatment.
- Fast Facts: BPH by Roger S Kirby and John D McConnell,
and Fast Facts: Prostate Cancer by Roger S Kirby, Michael
K Brawer, and Louis J Denis. They are slightly more detailed
books aimed at doctors, but they are both very understandable.
They are available from the Health Press.
There are also several patient groups and charities that
can provide booklets, leaflets, newsletters or other information.
The names and addresses of some of these can be found at the
end of this booklet. Several of these groups run a telephone
helpline.
Most important of all is to be assured that cases of BPH
nearly all respond to treatment, and that the majority of
prostate cancers do not prove fatal. Most men with these conditions
can look forward to many years of fruitful and enjoyable life.
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