How prostate cancer is diagnosed
Men who have symptoms will usually begin by seeing their GP. They 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.
Digital rectal examination (DRE)
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The rectum (back passage) is close to the prostate gland, so 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 (BPH - see symptoms) it's 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, the PSA test is not always reliable and some men who have prostate cancer will have a normal PSA. The PSA level can also be raised by:
The PSA level will also get higher as men get older.
In men aged 50-59, a PSA of 3 nanograms per millilitre (ng/ml) of blood or lower is considered normal.
In men aged 60-69, a PSA of 4 ng/ml or lower is considered normal.
In men of 70 and over, a PSA of about 5 ng/ml is considered normal.
PSA levels higher than this could be due to a prostate cancer and a biopsy may be recommended. Men with levels of 5 ng/ml 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.In most men with advanced prostate cancer the PSA level will be raised. Once the cancer has been treated, the level of PSA will fall. Measuring PSA levels can, therefore, be a helpful way of assessing the cancer and the effectiveness of treatment.
The following tests can be used to help diagnose cancer of the prostate, but you may not need to have all of them. 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.
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 often uncomfortable, and can sometimes be painful. You may be given a local anaesthetic to reduce the discomfort, and 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. This is quite normal.
Unfortunately, even if there is cancer in the prostate it may not be found by biopsy. This will happen in approximately 1 in 10-20 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.
We have information about further tests for prostate cancer.
How advanced prostate cancer is diagnosed
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If you have previously been diagnosed with early or locally advanced prostate cancer you may be attending the hospital or your GP for regular check-ups and blood tests. If you develop new symptoms, you will have tests to see if the cancer has spread. These will usually include a PSA test and a bone scan.
Other tests will depend on your symptoms. Some men are found to have prostate cancer after being investigated for bone pain. If you have bone pain but no other
symptoms, your GP may first arrange for you to have an x-ray or scan of the painful area. This may be an x-ray, isotope bone scan, CT scan or MRI scan.
If these suggest a secondary cancer in the bones, further tests will be done to find where the cancer started.