Usually, men who have symptoms begin by seeing their GP. Your GP will examine you and ask you about your general health.

The first tests for diagnosing cancer of the prostate are a digital rectal examination (DRE) and a PSA blood test.

As the rectum (back passage) is close to the prostate gland, your doctor can feel for any abnormalities in the prostate by inserting a gloved finger into the rectum. This may be uncomfortable but should not be painful.

If cancer is present in the prostate gland it may feel hard and knobbly, whereas with benign prostatic hyperplasia (see symptoms) it is usually enlarged, firm and smooth. However, often the prostate may feel normal, even when cancer cells are present.

A sample of blood is taken to check for PSA (prostate-specific antigen). PSA is a protein produced by the prostate and a small amount is normally found in the blood.

Men with cancer of the prostate tend to have more PSA in their blood. However, this test is not always reliable, as PSA levels also get higher as men get older. The level of PSA can also be raised by:

• urine infections
• recent prostate biopsies
• having a urinary catheter (a tube to drain urine)
• prostate or bladder surgery
• prostatic massage.

In many men who have prostate cancer the PSA level is normal.

• In a man aged 50–59, a PSA of 3 nanograms per millilitre of blood or lower is considered normal.
• In men aged between 60–69, a PSA of 4 nanograms per millilitre of blood or lower is considered normal.
• In men of 70 and over, a PSA of about 5 nanograms is considered normal.

PSA levels higher than this could possibly be due to a prostate cancer and a biopsy may be recommended. Men with levels of five nanograms per millilitre or above are usually referred for further tests.

As a general rule, the higher the level of PSA the more likely it is to be cancer. Once the cancer has been treated the level of PSA will fall. Measuring PSA levels can, therefore, be a helpful way of assessing the progress of the cancer and the effectiveness of treatment.

If your PSA level is raised, or if your GP feels any abnormalities during the digital rectal examination, they will refer you to hospital for a discussion about further tests.

Although the following tests can be used to help diagnose cancer of the prostate you may not need to have all of them done. The advantages and disadvantages of each method should be explained to you before you agree to any of them. Your doctor will be able to tell you how and when you will get the results.

Trans-rectal ultrasound scan (TRUS)

Ultrasound scans use sound waves to build up a picture of part 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 and density of the prostate. A sample of cells (biopsy) can be taken at the same time for examination under the microscope by a pathologist (see below). The scan may be uncomfortable but it only takes a few minutes.

Biopsy

If the initial tests (rectal examination, PSA or ultrasound) show that there is a possibility of cancer, you may be offered a biopsy, in which several samples of tissue (usually around 10) are taken from the prostate to be looked at under a microscope.

The biopsy is normally done at the same time as the ultrasound. A needle is passed through the wall of the back passage (rectum) and into the prostate. This test is usually uncomfortable, and can sometimes be painful, but it does not need a general anaesthetic. You may be given a local anaesthetic to reduce the discomfort.

Antibiotics are given to reduce the risk of infection. In the 24 hours following this test it is important to drink plenty of fluids. For up to a few weeks you may notice bleeding when passing water, opening your bowels or in your semen after sex.

Unfortunately, even if there is cancer in the prostate it may not be found by biopsy. This will happen in approximately one in 10 or 20 men tested (5–10%). If a biopsy is negative it may need to be repeated (this may detect a cancer that was missed first time).

Sometimes the PSA may be measured again after a few months and the biopsy repeated if the PSA level starts to rise.