Screening for prostate cancer

• A quick guide to what's on this page
• The aim of cancer screening
• The PSA blood test
• Screening for prostate cancer
• The benefits and disadvantages of screening for prostate cancer
• Screening for men at higher risk of prostate cancer

Screening for cancer is an important part of cancer care. The aim of screening is to diagnose disease

• At an early stage
• Before symptoms start
• When it is easier to treat
• When it is more likely to be curable

Before screening can be carried out, there must be an accurate test to use. At the moment, there is no single, effective screening test to accurately diagnose most early prostate cancers in men who don't have symptoms.

The use of the PSA blood test as part of a screening programme is still under discussion in the UK and large international trials are being carried out to research whether prostate screening could be helpful.

If you are concerned that you may have prostate cancer, you can go and talk to your GP about the risks and benefits of having a PSA (prostate specific antigen) test.

The PSA test shows the amount in the blood of a protein produced by prostate cells. If the level of PSA is higher than normal it could be due to a prostate cancer but there are other causes of raised PSA, such as infection, a non cancerous enlarged prostate and even exercise and sex. So if you have a raised PSA level you will need to have more medical tests to find the cause.

If you have your PSA checked, your doctor will do a rectal examination as well as the blood test. Rectal examination is also called DRE (digital rectal examination). The doctor puts a gloved finger into your back passage to feel your prostate. This helps the doctor to decide whether your PSA reading is likely to indicate a cancer or not. If you have an abnormal PSA and your doctor thinks your prostate feels unusual, it is more likely to be a cancer than if you have an abnormal PSA but your prostate feels normal.

Generally speaking, the higher the PSA level, the more likely it is that there is a cancer in the prostate. But in early prostate cancer, PSA levels are usually relatively low. It is not possible to pick out a particular PSA reading and say “people above this level have cancer and those below do not”. The level of PSA varies from man to man. It naturally gets higher as men get older.

If you have a normal PSA test result, the current thinking amongst experts is that you do not need to have another test for at least 2 years. If you have a result that your doctor considers borderline, you should have a repeat test in 1 to 3 months to see if the level is going up or is stable. There are guidelines for GPs about what to do in these circumstances.

PSA testing is used in the USA to screen men for prostate cancer. The American Cancer Society support screening with a PSA blood test and rectal examination for men over 50 and at the age of 45 for men thought to be at high risk of prostate cancer (African American men and men with a family history of prostate cancer). The National Comprehensive Cancer Network supports screening for men from the age of 40.

But in the UK, there is no national screening programme for prostate cancer because trials have not yet shown clear evidence that screening will reduce deaths from this disease. Also, many men diagnosed with prostate cancer have very slowly growing cancers that will never cause any symptoms or problems in their lifetime. If the cancer is diagnosed and treated, the treatment can cause side effects for some men that may greatly reduce their quality of life. Possible side effects include erection problems (impotence) and inability to completely control urine (incontinence). So at the moment there is no clear benefit in diagnosing prostate cancer early and it may actually cause harm for some men.

In the UK and other European countries, PSA testing is not recommended for screening because

• Some men with prostate cancer do not have a raised PSA level
• 2 out of 3 men with a raised PSA do not have prostate cancer
• There is uncertainty about the best way to treat early prostate cancer
• The treatments can cause unpleasant side effects

If PSA was used as a screening test, some men who did have prostate cancer would be told that they didn’t. Two thirds of men with a raised PSA level would go on to have other tests such as a needle biopsy and rectal ultrasound when they did not actually have a cancer. These tests can be uncomfortable and many men find them embarrassing. They also have risks. Some men who have a needle biopsy will have infection or persistent bleeding afterwards.

If prostate cancer screening was introduced, some men would have their cancer detected early and may live longer than if they did not have screening. But this is likely to help very small numbers of men because prostate cancer is not usually a quickly growing disease.

Most men with early prostate cancer don't have symptoms. The cancer can grow very slowly in many men and they are unlikely to die from it. These men don't really need treatment. The treatment has side effects and could cause more problems than the cancer.

Some men have faster growing cancers and do need treatment. But, unfortunately, doctors cannot always tell with any accuracy which prostate cancers are likely to grow quickly and need treatment and which can safely be left alone.

So if prostate cancer screening was introduced

• Some men with cancer would be missed
• Other men without cancer would be given tests they did not need
• Some men with very slow growing cancers would be given treatment they did not need

There is still a lot of discussion worldwide about prostate cancer screening. It is not clear whether the risks outweigh the benefits It is also not clear whether a screening programme using the current tests will reduce deaths from prostate cancer.

A trial called ProtecT has been looking into treatment for prostate cancer for some years. It aims to find the best way of dealing with early prostate cancer. Now, Cancer Research UK and the Department of Health are funding an extension to this trial. The extension will compare the outcomes for men who weren't screened for prostate cancer with those who had PSA testing within the ProtecT trial. This trial has closed and it will be a few years before we know the results.

Two large international trials are looking into prostate cancer screening. In Europe the large ERSPC trial has stopped recruiting patients. In the USA the PLCO trial has closed and men taking part are now being followed up. Early results were released in March 2009.

The PCLO study compared 2 groups of men. One group had screening every year with the PSA test and rectal examination. The other group did not have screening as part of the study. The researchers found that screening did not reduce the number of deaths from prostate cancer after 11 years of follow up. The number of deaths was small in both groups. But the results are not clear, because some men in the trial group who were not supposed to have screening had PSA tests from their own doctors.

The ERSPC study is being carried out in 7 European countries. It is comparing men who had screening for prostate cancer with a PSA test every 4 years to men who had no screening. The early results presented in 2009 seemed to show that PSA tests can detect very early prostate cancer and may reduce the number of deaths from the disease by 20%. But the men in the study need to be followed up for longer to be sure. So they will carry on being followed up over the next few years to see whether screening reduces the number who die due to prostate cancer. In January 2010 the trial reported that for every eight men screened four yearly, one received a false positive result and would then need unnecessary tests such as prostate biopsy. The study also found that men who received a false positive result were twice as likely to refuse screening in the future.

The combined final results of the PCLO and ERSPC trials are due later in 2010.

If you would like to look for prostate cancer trials in the UK, go to our clinical trials database and choose 'prostate' from the drop down menu of cancer types.

There is some evidence to show that prostate cancer can run in families. This means that if a relative has been diagnosed with prostate cancer your risk is doubled. The risk is higher if it is

• Your brother who was diagnosed
• The relative was younger than 60
• You have several relatives diagnosed with prostate cancer

Currently doctors don’t know the best way to follow people up who are at high risk of developing prostate cancer. A trial called IMPACT aims to find this out. It is looking at men who have inherited a gene change that increases their risk of developing prostate cancer. It will be some time before we know the results of this trial. The researchers will need to follow up the men for at least 5 years. You can find out more about prostate cancer trials on our clinical trials database.

So for now if you have a family history of prostate cancer, you may want to discuss screening with your GP. They will look at your family history and the ages of the men who have prostate cancer in your family. If you have a strong family history they may suggest that you have regular PSA tests and a rectal examination. Your GP may refer you to a genetics clinic if they think that may be helpful. Generally speaking if you have a strong family history, doctors usually suggest screening from around the age of 40 to 45.