Understanding the PSA test

This section gives information about the PSA blood test which can help to detect prostate cancer. It aims to help you decide whether to have the test.

This information can help you if:

You have heard about the test and wonder if you should have it.
You have no symptoms but just want to check that you don't have prostate cancer.
You have symptoms that could be caused by prostate cancer.

Deciding about the PSA test

There is no right or wrong answer when it comes to having a PSA test. There are many unanswered questions about whether a PSA test is helpful in diagnosing prostate cancer, and there are also questions about whether treatment is necessary for early prostate cancer. Many prostate cancers grow very slowly, and for some men the side effects of treatment may be worse than the effects of the cancer itself, so it can be difficult to decide whether or not to have treatment.

People deal with this uncertainty in different ways. Some men want to have tests for early prostate cancer and treat it if it occurs. Other men do not want to know if they have an early prostate cancer because they think that, on balance, having that information would do them more harm than good. With the help of your doctor, and this information, you can make the right decision for you.

The prostate gland

The prostate gland is only found in men, and it sits just below the bladder, close to the rectum (back passage). It is about the size and shape of a walnut and running through the middle of it is the urethra (the tube which carries urine and sperm out through the penis).

A diagram showing the male sex organs

The prostate produces a thick, white fluid called semen, which mixes with the sperm made by the testes. It also produces a protein called prostate specific antigen (PSA), which liquefies the semen. The growth of the cells within the prostate gland and the way that the gland works is dependent on the male sex hormone, testosterone, which is produced in the testes.

You are unlikely to be aware of your prostate unless it causes you trouble. The most common prostate problem is prostate enlargement (called Benign Prostatic Hypertrophy, or BPH). This is common in men over the age of 50 and it can cause the following symptoms:

Difficulty in passing urine

Passing urine more often than usual, especially at night
Pain on passing urine
Rarely, blood in the urine or semen

Note: BPH is not cancer and is not the same as prostate cancer

Prostatitis (inflammation of the prostate gland) can also cause the above symptoms. Prostatitis can be caused by infection, which is treated with antibiotics. It can also be caused by physical injury to the prostate gland, or some autoimmune diseases (in which the body's immune system damages the body's own cells).

Note: Prostatitis is not prostate cancer.

Prostate cancer

1 in 14 men will be diagnosed with prostate cancer during their lifetime. It is the most common cancer in men. Around 30,000 men in the UK are diagnosed with prostate cancer each year.

Around 10,000 men die each year from prostate cancer, generally some years after they were diagnosed. It generally occurs in older men; 4 out of every 5 prostate cancers are diagnosed in men over the age of 65.

Unlike many other cancers, prostate cancers are often present for years without a man or his doctor knowing about it. This is because they are usually slow growing and often do not cause any symptoms at all during a man's lifetime. By the age of 80, about half of all men will have some cancer cells in their prostate; but only 1 in 30 men will actually die from it. On the other hand, some types of prostate cancer are faster growing and can spread to other parts of the body. If the cancer does spread it is most likely to be carried in the bloodstream to the bones, which can cause pain and eventual death.

Causes of prostate cancer

The causes of prostate cancer are not known, but some things do seem to affect your chances of developing the disease:

Age – prostate cancer is rare in men under 50 years of age, and your risk of developing it increases as you get older
Having relatives who have had prostate cancer. If one close relative (father, uncle, brother) has prostate cancer this roughly doubles your risk of developing it. Having two close relatives with prostate cancer increases your risk by about four times.
African-American and African-Caribbean men seem to be more at risk than other ethnic groups.
Exposure to cadmium and x-rays increases the risk of prostate cancer.

Several nutrients present in our diet which may offer protection from developing prostate cancer are being researched. These include lycopene from tomato-based foods, vitamin E, soya, vitamin D and selenium. Some research suggests that eating a diet without much animal fat, dairy produce and protein may reduce your risk.

Symptoms of prostate cancer

Cancers that are completely contained within the prostate gland are known as early prostate cancer.

Men with early prostate cancer may not have any symptoms at all. Prostate cancers usually only cause symptoms when they are large enough to press on the urinary tube (urethra) or disturb the bladder. For that reason the symptoms of prostate cancer, when they do appear, are very similar to the symptoms of simple enlargement of the prostate (BPH):

Pain or difficulty when passing urine
Passing urine more frequently than usual, and especially at night
Rarely, blood in the urine or sperm.

Note: Most men with these symptoms will not have prostate cancer.

Prostate cancers can be very slow growing and even if the cancer cells have spread into the tissues around the prostate (known as locally advanced prostate cancer), they may not cause any problems with passing urine. Sometimes a prostate cancer can spread to the bones. This is known as metastatic or secondary bone cancer and symptoms might include pain in the affected bone (most commonly the back, hips or pelvis).

Tests for prostate cancer

There are four main ways to check the prostate for cancer:

A digital rectal examination This involves the doctor inserting a gloved finger into your rectum (back passage) to feel the prostate. This is good for finding advanced cancers, but overall it will detect less than half of prostate cancers. It may be uncomfortable, but it is quick and it should not be painful.
The PSA test This is a blood test. A small sample of blood is taken from your arm using a needle and syringe (see next page for more information).
Trans-rectal ultrasound scan (TRUS) Ultrasound scans use sound waves to build up a picture of the inside of the body. To scan the prostate gland a small probe is passed into the back passage and an image of the prostate appears on a screen. This type of scan is used to measure the size of the prostate. A sample of cells (biopsy) can be taken at the same time (see below). The scan may be uncomfortable but it only takes a few minutes.
A transrectal needle biopsy of the prostate A biopsy is usually done at the same time as an ultrasound. This involves putting a plastic probe into the rectum (back passage) and passing a needle through the wall of the rectum to take a sample from the prostate. The doctors will then use a microscope to look for any cancer cells in the sample. This is how doctors can tell for certain if you have prostate cancer, usually after a PSA test and rectal examination.

The PSA test and transrectal needle biopsy are described in more detail on the following pages.

The PSA test

The PSA test is a blood test. PSA (Prostate Specific Antigen) is a protein made by the prostate gland, which naturally leaks out into the bloodstream. The PSA test measures the level of PSA in your blood.

Sometimes a raised PSA level can be a sign of prostate cancer. More often though, it is caused by something less serious like an inflamed prostate (prostatitis), or an enlargement of the prostate that often comes with ageing (benign prostatic hypertrophy, or BPH). A single PSA test cannot show you whether a prostate cancer is present, or whether it is slow or fast growing. The level of PSA can also be raised by:

infections
recent prostate biopsies
having a urinary catheter in (a tube to drain urine)
prostate or bladder surgery
prolonged exercise, such as long-distance running or cycling
ejaculation

How reliable is it?

The PSA test is not a foolproof test for prostate cancer.
Two out of three men with a raised PSA will not have any cancer cells in their prostate biopsy.
Up to 1 in 5 men with prostate cancer will have a normal PSA result.

If your PSA level is high

There are no hard and fast rules, and even expert doctors do not always agree on the best course of action. What happens next depends on:

whether or not you have any symptoms
your personal risk of prostate cancer
how high the PSA level is.

The older you are, the higher your PSA level is likely to be (whether or not you have got prostate cancer). So what is 'normal' depends to some extent on your age. In a man of 50, a PSA of up to 2.8 nanograms* per millilitre of blood is considered normal. In a man of 70, a PSA of up to 5.3 nanogrammes per ml is considered normal.

As a rough guide, these are the three main options after a PSA test:

PSA normal
You are unlikely to have cancer. No further action is needed.
PSA slightly raised
You probably do not have cancer, but might need to have another PSA test in a few months.
PSA is definitely raised
You probably need to have a prostate biopsy to find out if cancer cells are present.

* a nanogram is a billionth of a gram

Transrectal needle biopsy

If the level of PSA in your blood is higher than normal, you will probably need to have a biopsy. This is because doctors can only tell for certain if you have prostate cancer by taking cells from the prostate and then looking at them under a microscope.

A biopsy involves using an ultrasound scanner to guide a plastic probe into the rectum. A needle is then passed through the wall of the rectum to take a sample of cells from the prostate gland. Men who have had this done tend to describe it as uncomfortable or painful, though you won't need a general anaesthetic.

The biopsy is not without its own risks. As there is a chance of infection, you will be given antibiotics after the procedure. For every 100 men having a biopsy, about 3 will have to have a second course of antibiotics, and 1 will need to be admitted to hospital for antibiotics to be given by drip (into a vein). About 30 men may have some bleeding in the urine or semen for up to three weeks afterwards. The risk of death from a biopsy is less than 1 in 10,000.

The biopsy itself is not totally accurate. If the biopsy does not show any cancer cells, that does not completely rule out cancer. Of every five men who have cancer of the prostate, the biopsy will miss the cancer in about one of them. So you might need to have further PSA tests and biopsies to monitor your prostate.

If you have early prostate cancer

Although the PSA test may pick up a cancer early, there is no certainty that treating early prostate cancers helps men live any longer. Most men with early prostate cancer will not die as a result of it; this is particularly true of men in their 70s or 80s, or with a slow-growing cancer. It is also worth bearing in mind that if you were to have surgery or radiotherapy (the two main treatments for early prostate cancer), there can be effects such as erection problems, leaking of urine (incontinence) or damage to the rectum (back passage).

Treatment options

There are five main options if you have early prostate cancer:

1. Active surveillance (active monitoring)
2. Radical Prostatectomy
3. External beam radiotherapy
4. Brachytherapy
5. Hormonal therapy

1. Active surveillance (active monitoring)

Most early-stage prostate cancers may be very slow growing and may never cause any symptoms. For this reason, some patients and specialists decide to wait and see whether the cancer is getting bigger (progressing) before starting any treatment. The 'active surveillance’ approach involves regular check-ups with PSA tests, rectal examination of the prostate and possibly repeat biopsies.

Benefits: Many men who choose active surveillance will avoid the complications of surgery, radiotherapy, or hormonal therapy.

Risks: Some men find it difficult just to wait and see if their cancer progresses before starting any therapy. Some men will need surgery, radiotherapy or hormonal therapy if their cancer shows signs of developing.

2. Radical Prostatectomy

A major surgical operation to remove the whole prostate gland.

Benefits: Removing the entire prostate may stop an early cancer from spreading and may result in a cure. Radical prostatectomy appears to prolong life for men with more fast growing cancer, but for men with small, slowly growing cancers the benefits are debatable, and probably only apply to younger men. In 2 out of 5 men, the cancer cells are not fully removed, and therefore the operation may not result in a cure.
Risks: For every 1000 men: 5 will die from problems caused by surgery, up to 200 will develop leaking of urine, and about 800 will have problems getting an erection.

3. External beam radiotherapy

High-energy rays are used to destroy cancer cells.

Benefits: Radiotherapy may lead to a cure in early prostate cancer, but as with prostatectomy, the benefits in small, slowly growing cancers are uncertain. A complete course takes up to seven weeks. Giving hormone therapy before and during the radiotherapy may improve the results.

Risks: For every 1000 men who have external beam radiotherapy: up to 300 will develop occasional bleeding from the rectum (back passage); about 100 may have bleeding, a change in bowel habit and some discomfort; and up to 700 will develop erection problems (though this depends on age). Rarely, some men may have leakage of urine or incontinence of urine.

4. Brachytherapy

A new type of radiotherapy, which uses radioactive seeds inserted into the prostate.

Benefits: Same as for external beam therapy. A simpler procedure than external beam radiotherapy, as it usually only involves one planning session and one treatment session (under general anaesthetic) during a stay in hospital of one or two days.

Risks: Side effects to the bladder, such as inflammation (cystitis) may be more severe than external beam radiotherapy, but bowel problems (diarrhoea) and impotence are expected to be less common. Scar tissue may cause gradual narrowing of the urethra which may need to be treated.

5. Hormonal therapy

Lowers the levels of testosterone in the body, by removing the testes or using tablets or injections. Hormonal therapy may be used on its own or given with radiotherapy treatment.

Benefits: Can slow or stop the growth of cancer cells for many years. Does not involve surgery or radiation so there is little risk of bowel or bladder problems.

Risks: It will not get rid of all the cancer cells if it is the only treatment given and can cause a range of side effects that include breast swelling and hot flushes, impotence and lowered sex drive.

Advantages and disadvantages of having the PSA test

First, ask yourself if you are at particular risk of prostate cancer.

Your risk increases:

The older you are (but in older men, prostate cancer is less likely to cause problems).
If you have close relatives who have had prostate cancer (such as a father, uncle or brother).
If you are of African-Caribbean or African-American descent.

Possible advantages

It could reassure you if the test is normal.
It can find cancers before any symptoms develop.
Treatment in the early stages could help you live longer and avoid the complications of cancer (although there is no good research evidence that this is so).

Possible disadvantages

It could read normal when there is cancer in the prostate, and falsely reassure you that all is well.
It could lead to anxiety, even though you have no cancer.
It could lead to a biopsy, even though you have no cancer.
If you have cancer it cannot tell you if it is likely to cause problems in the future.
Treatment of early prostate cancers might not help you live longer.
Treatments for early prostate cancer have risks and may cause side effects that can affect your quality of life.

Questions to help you decide whether to have the PSA test

To help you make your decision, try answering these three questions:

What would you choose to do if your PSA level is found to be high?
What would you do if the tests find that you have an early prostate cancer?
What difference will it make for you to know?

If you can answer these three questions, focusing on what is really important to you, you will have your own best PSA decision.

Deciding whether or not to have a PSA test can be very difficult and we hope that this information has helped you. However, if you have further questions you can contact your GP who will be able to answer them. You can also contact the specialist nurses at Cancerbackup who can discuss this with you. They can also send you more detailed information on the treatments mentioned in this section.

References

The information in this section is based on the Cancerbackup booklet, Understanding the PSA test, which was produced in accordance with the following sources and guidelines:

The NHS Prostate Cancer Management Programme. NHS 2002.
The NHS cancer screening website, prostate cancer section: www.cancerscreening.nhs.uk/prostate/index.html. June 2005.

Understanding the PSA blood test