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How is prostate cancer diagnosed?

There is no single, simple test to detect prostate cancer. Two commonly used tests are the PSA blood test by your GP and the digital rectal examination by a urologist. These tests, used separately or together, only show changes in the prostate. They do not diagnose prostate cancer. If either test shows an abnormality, you will be referred to a urologist for further evaluation.

Health professionals use Australian clinical guidelines to help decide when to use PSA testing and other early tests for prostate cancer.

Prostate specific antigen (PSA) is a protein made by both normal prostate cells and cancerous prostate cells. PSA levels are measured using a blood test, and the results are given as nanograms of PSA per millilitre (ng/mL) of blood. The PSA test does not specifically test for cancer.

If the PSA result is higher than the typical range for your age (e.g. above 3 ng/mL for people aged 50–59) or is rising quickly, this may indicate the possibility of prostate cancer. However, the amount of PSA in the blood can be raised even when you do not have cancer. Other factors that can increase PSA levels include benign prostate hyperplasia, recent sexual activity, an infection in the prostate, or a recent digital rectal examination. Some people with prostate cancer have normal PSA levels.

Because your PSA levels can vary from day to day, your doctor will usually repeat the test to help work out your risk of prostate cancer.

There are some other blood tests your doctor may suggest:

Free PSA or free-to-total test – This measures the PSA molecules in your blood that are not attached to other blood proteins (free PSA). This test may be suggested if your PSA score is above 3 ng/mL and your doctor is not sure whether you need a biopsy. The free PSA test measures the ratio of free PSA to total PSA. A low level of free PSA compared to total PSA may be a sign of prostate cancer.

Prostate health index (PHI) – This measures three different forms of the PSA protein. PHI is not widely used in Australia and is not covered by Medicare.

To do a digital rectal examination (DRE), the doctor slides a finger into your bottom to feel the back of the prostate. They’ll wear gloves and put gel on their finger to make the examination more comfortable. If the specialist feels a hardened area or an odd shape, further tests may be done.

These changes do not always mean you have prostate cancer. On the other hand, a normal DRE does not rule out prostate cancer, as the examination is unlikely to pick up a small cancer or one the finger can’t reach.

A DRE is no longer recommended as a routine test for people who do not have symptoms of prostate cancer, but it may be used to check for any changes in the prostate before doing a biopsy.

An MRI (magnetic resonance imaging) scan uses a powerful magnet and radio waves to build up detailed pictures of the inside of the body. Your doctor may suggest this scan to help work out if a biopsy is needed. An MRI can be used to show whether the cancer has spread from the prostate to nearby areas. It can also help guide the biopsy needle.

A specialised type of MRI called mpMRI (multi-parametric magnetic resonance imaging) is used for people suspected of having prostate cancer. This combines the results of three MRI images to provide a more detailed image.

Before an MRI scan, a dye may be injected into a vein to make the pictures clearer. You will lie on an examination table that slides into the scanner, a large metal cylinder open at both ends. The scan is painless but can be noisy and may take 30–40 minutes. Some people feel claustrophobic in the cylinder. Talk to your doctor or nurse before the scan if you feel anxious in confined spaces. Also let them know if you have a pacemaker or any other metallic object in your body. The magnet can interfere with some pacemakers, but newer pacemakers are MRI-compatible.

The dye used in an MRI scan can cause allergies. If you have had a reaction to dyes during a previous scan, tell your medical team beforehand. You should also let them know if you have diabetes or kidney disease.

Medicare provides a rebate for MRI scans, but there may be a gap fee. Ask your doctor what you may need to pay.

You may have a biopsy after an MRI scan. Your specialist should explain the risks and benefits of having a prostate biopsy and give you time to decide if you want to have a biopsy.

During a biopsy, small amounts of tissue are taken from the prostate using a special needle. The samples are sent to a laboratory, where a specialist doctor called a pathologist looks for cancer cells in the tissue.

There are two main types of prostate biopsy. In a transperineal (TPUS) biopsy, the needle is inserted through the skin between the anus and the scrotum. In a transrectal (TRUS) biopsy the needle is inserted through the rectum. A transperineal biopsy is most commonly used.

A transperineal biopsy is normally done under general anaesthetic. The specialist passes a small ultrasound probe into your back passage (rectum). An image of the prostate appears on the screen, which helps guide the needle into place.

A biopsy can be uncomfortable. After the procedure, there may be a small amount of blood in your urine or bowel motions for a few days, and you may see blood in your semen for a couple of months. It usually takes 1–2 weeks for the biopsy results to come back.

If the biopsy results show prostate cancer, other tests may be done to work out whether the cancer has spread. You may also have regular tests to check PSA levels, prostate cancer activity and general health.

Bone scan – This scan can show whether the prostate cancer has spread to your bones. A tiny amount of radioactive substance will be injected into a vein. You will need to wait for 1–2 hours while the substance moves through your bloodstream to your bones. Your whole body will then be scanned with a machine that detects radioactivity. A larger amount of radioactivity will show up in any areas of bone with cancer cells. The scan is painless and the radioactive substance passes from your body in a few hours.

CT scan – A CT (computerised tomography) scan uses x-ray beams to create detailed pictures of the inside of the body. A CT scan of the abdomen can show whether cancer has spread to lymph nodes in that area. A dye is injected into a vein to help make the scan pictures clearer. You will lie still on a table that moves slowly through the CT scanner, which is large and round like a doughnut. The scan itself takes a few minutes and is painless, but the preparation takes 10–30 minutes.

The dye used in a CT scan can cause allergies. If you have had a reaction to dyes during a previous scan, tell your medical team beforehand. You should also let them know if you have diabetes or kidney disease.

PET scan – A PET (positron emission tomography) scan may help detect cancer that has spread or come back. A PET scan involves injecting a small amount of a radioactive solution. Cancer cells take up more of this solution and show up brighter on the scan. For prostate cancer, the scan usually uses gallium to show prostate specific membrane antigen (PSMA). The cost of this scan is not currently covered by Medicare.

This information is reviewed by

This information was last reviewed in March 2020 by the following expert content reviewers: Dr Amy Hayden, Radiation Oncologist, Westmead and Blacktown Hospitals, and Chair, Faculty of Radiation Genito-Urinary Group (FROGG), The Royal Australian and New Zealand College of Radiologists, NSW; Prof Shomik Sengupta, Professor of Surgery and Deputy Head, Eastern Health Clinical School, Monash University, and Visiting Urologist and Uro-Oncology Lead, Urology Department, Eastern Health, VIC; A/Prof Arun Azad, Medical Oncologist, Urological and Prostate Cancers, Peter MacCallum Cancer Centre, VIC; Ken Bezant, Consumer; Dr Marcus Dreosti, Radiation Oncologist, GenesisCare, and Clinical Strategy Lead, Oncology Australia, SA; A/Prof Nat Lenzo, Nuclear Physician, Specialist in Internal Medicine, Group Clinical Director, GenesisCare Theranostics and The University of Western Australia, WA; Jessica Medd, Senior Clinical Psychologist, Department of Urology, Concord Repatriation General Hospital, and HeadwayHealth Clinical and Consulting Psychology Services, NSW; Caitriona Nienaber, 13 11 20 Consultant, Cancer Council Western Australia; Graham Rees, Consumer; Kerry Santoro, Prostate Cancer Specialist Nurse, Southern Adelaide Local Health Network, SA; A/Prof David Smith, Senior Research Fellow, Cancer Research Division, Cancer Council NSW; Matthew Starr, Consumer.