Prostate Cancer

Tests for prostate cancer

These tend to follow a sequence in men requesting screening for or suspected of having prostate cancer.

Clinical examination: Digital Rectal Examination (DRE) by your doctor can exclude an obvious cancer. If anything suspicious is found, or if more confirmation is required, then a PSA test may help.

Prostate Specific Antigen (PSA): this is a protein made by normal and cancerous prostate cells which naturally leaks into the blood where it can be measured. Sometimes a raised PSA level can identify early prostate cancer before symptoms develop because more PSA may leak from the cancerous cells. If abnormally raised, it may guide decisions about the next stage of diagnostic tests. The PSA test is not however specific for cancer. Usually, it suggests something less serious including prostate inflammation (prostatitis) or prostate enlargement (BPH). PSA cannot absolutely determine whether the prostate cancer is slow or fast growing unless it is performed serially

The significance of a raised PSA may depend on a number of factors including age, the presence of urine symptoms, a family history of cancer and the PSA level. Normal levels are age-dependent and there is a range of normal PSA readings at different ages. If you are 50 years, the upper normal limit is around 2.8 but this increases to 5.3 if you are 70.

Transrectal ultrasound (TRUS): may be useful; biopsies may be taken at the same time and sent to the laboratory for examination under the microscope. This is the key test to be certain of a cancer diagnosis as prostate cancer can only be diagnosed by microscopic examination of cells taken from a biopsy. This can be an uncomfortable and/or painful procedure. Sometimes local anaesthetic is offered. Biopsy itself carries a risk e.g. from infection (so antibiotics are usually suggested) and about 30% of men may bleed from the urine or after sex for awhile.

Once a diagnosis of prostate cancer is made, other tests can be performed to help determine how extensive the cancer is. These include special imaging (X-rays and scans) to determine the extent of cancer within the prostate and throughout the body.

Screening

There is no proven effective screening test for early prostate cancer. This only started to become possible with the advent of PSA, despite all its limitations. Screening aims to diagnose cancer at the earliest stage possible and before symptoms appear. Advocates propose screening on the basis that this makes treatment easier when cure is most likely. It remains to be proved however whether early diagnosis makes a difference to eventual survival. Also, the side-effects of diagnosis and treatment may be quite unpleasant. Some doctors strongly believe that early diagnosis makes a difference to outcome whereas others are much more circumspect. There are two trials worldwide currently in progress to attempt to answer the question about whether screening may be useful. These are the ERSPC trial (in Europe) and the PLCO trial (in the USA). Hopefully when all the results are available, it will be possible to answer these questions with authority.

In the UK, current thinking is that the risks of screening exceed the benefits. Routine PSA screening in the UK remains under discussion although it is widely used, especially in the USA and Europe. However every man over 50 has a right to a PSA test if they want to. In the USA, PSA tests from the age of 50 are offered regularly.

The reasons for this are complex. A normal PSA does not guarantee freedom from cancer. Similarly, a high result does not automatically mean cancer. With a PSA between 4 and 10, between 20-25% of men might be found to have a cancer (or conversely, 75-80% will not). Generally, higher PSA levels suggest a greater likelihood that cancer is present. It may be appropriate to consider biopsy (taking a sample of the prostate tissue) using TRUS to try and confirm or exclude the suspicion. Other causes of raised PSA include infection, benign prostate enlargement, exercise and sex. PSA used alone therefore has the potential to mislead. Some men with prostate cancer could be told that they were clear (giving false reassurance) whilst many more without cancer might progress unnecessarily to additional tests including TRUS and biopsy which are uncomfortable and can cause side-effects such as infection and bleeding. Also, there are several different types of PSA test; there is no standard best one. Results may differ by a much as 30% between laboratories and individual tests.

Screening programmes are of little value if there is no effective treatment. Prostate cancer is frequently not serious. Many have no symptoms. It can grow very slowly and few are likely to die from it. These men don't need treatment. Others may benefit from treatment but the problem is a lack of any accurate method to identify those prostate cancers which may eventually cause death from those that may safely be left alone.

There is still substantial debate about prostate cancer screening. How do the risks of missing cancers compare with the side effects from tests? Will a screening programme using currently available tests actually reduce deaths from prostate cancer?

A diagnosis of prostate cancer may not necessarily be life threatening. Radical, curative treatment may not be required. Most men with early prostate cancer that is detected after a PSA test will have the type of cancer which grows slowly and which would be expected not to cause problems during the natural lifespan of a man.

No one knows for sure whether PSA testing should be used routinely to screen for prostate cancer. Many doctors believe that we do not know enough about the good and bad effects of screening and that it is too early to introduce screening for all men in the UK.

Possible suggestions by your doctor

It can be very difficult to distinguish between those who may need to see a specialist and those with unimportant disease. With some symptoms, it may be sensible to wait and see if they improve, whilst others might suggest rapid referral to hospital. The Department of Health has produced guidelines for GP's to help them decide when patients need to be seen urgently in hospital.

Important facts:

Almost all men with prostate cancer (over 99%) are at least 50 years old and75% are over 70 years old
Prostate (waterwork) symptoms alone do not necessarily suggest cancer; these days, a raised PSA or abnormal DRE is the most common way in which prostate cancer might be detected
PSA levels depend on age
Men with a first degree relative (mother, father, son or daughter) who have prostate or breast cancer are at a higher risk of developing prostate cancer

The 2 week wait - when hospital referral may be urgent

Reasons for urgent (within 2 weeks) referral for possible prostate cancer are

A PSA that is high for your age
A raised PSA in the presence of bone pain or abnormal DRE