Screening for 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. Large trials are being carried out to research whether prostate screening could be helpful. You can read about screening tests on the diagnosing prostate cancer research page.

If you are worried 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 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.

There is currently no national screening programme in the UK for prostate cancer. PSA testing is not recommended for routine screening because it is not a very accurate test. Some men with prostate cancer do not have a raised PSA level. And 2 out of 3 men with a raised PSA level do not have prostate cancer. So, 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.

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). 

A lot of research has been carried out into prostate cancer screening in recent years. A review of 6 large prostate cancer screening trials reported in 2010. It found that screening increased the number of men diagnosed with early stage prostate cancer. But screening did not reduce deaths from prostate cancer or help men to live longer. A 20 year Swedish study reported in 2011 and also found that prostate cancer screening in the general population has very limited benefit. 

The European Randomised Study of Screening for Prostate Cancer (ERSPC) was set up in 1991 and is ongoing. It involves 182,000 European men aged 50 to 74, who were divided into two groups. One group was offered PSA screening on average once every 4 years, while the other group did not have screening. The latest findings were published in The New England Journal of Medicine in 2012. The study found that fewer men died from prostate cancer when they had screening. But the study still does not tell us whether this benefit outweighs the side effects of treatment, such as impotence and incontinence. The screening also used a lot of resources. The researchers said that to prevent one death from prostate cancer over the 11 years, 1,055 men had to be invited for screening, with 37 cancers being detected.

A similar study in the US is called the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial. For prostate cancer it involved 76,000 men aged 55 to 74. Half of the men in the study were offered a PSA test every year for six years. After 10 years the researchers found that more men in the screening group were diagnosed with prostate cancer than in the other group. But the number of men in each group who died was very similar.

So currently it is not clear whether it is helpful to regularly screen men for prostate cancer. Researchers are trying to find tests that are better than the PSA test in the hope that this will make screening more worthwhile. You can read about these tests on the research into diagnosing prostate cancer page.

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 higher than in the general population. 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 UK 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 aims to look at 1,700 men who have inherited faulty BRCA1 or BRCA2 genes. 

Early results of the IMPACT trial were released in September 2010 for the first 300 men. The men had yearly PSA testing. The results show that regular PSA screening may be helpful for men at higher risk of prostate cancer. It found that men with faulty BRCA genes who developed prostate cancer tended to have faster growing cancers than men without the faulty genes. 

These are early results and it will be some time before we know the final results of this trial. The researchers 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 your GP may suggest that you have regular PSA tests and a rectal examination. They may refer you to a genetics clinic if they think that may be helpful. Generally, doctors usually suggest screening from around the age of 40 to 45 if you have a strong family history that raises your risk of cancer.