Tests for prostate cancer

Prostate specific antigen (PSA) blood tests

Prostate specific antigen (PSA) is a protein made by both normal prostate cells and cancerous prostate cells. PSA is found in the blood and can be measured with a blood test. The test results will show the level of PSA in your blood as nanograms of PSA per millilitre (ng/mL) of blood.

There isn’t one normal PSA level for everyone. If your PSA level is above 3 ng/mL (called the threshold), it may be a sign of prostate cancer. But younger people or people who have a family history of prostate cancer may have a lower threshold. PSA levels can vary from day to day. If your PSA is higher than expected, your GP should repeat the test within 1–3 months to help work out your risk of prostate cancer.

Your PSA level can be raised even when you don’t have cancer. Other common causes of raised 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 for their age range.

Free PSA or free-to-total test

Your doctor may also suggest that you have a free PSA test. This test measures the ratio of free PSA to total PSA in your blood. Free PSA is PSA that is not attached to other blood proteins. This test may be suggested if your PSA level is 4–10 ng/mL and your doctor is not sure whether you need further tests. A low free-to-total PSA ratio may be a sign of prostate cancer.

Digital rectal examination (DRE)

A urologist may do a DRE. Wearing gloves, they put gel on their finger and then insert it into your rectum (bottom) to feel the back of the prostate. Some people may have an mpMRI instead of a DRE.

You may have further tests if the doctor feels a hard area or an odd shape. These changes do not always mean you have prostate cancer. Having a normal DRE also does not rule out prostate cancer, as the finger can’t reach all of the prostate and may not feel a small cancer.

It’s not recommended that GPs to do DREs. However, some may choose to do a DRE, depending on your PSA results and urinary symptoms. But a urologist may do a DRE as part of examining your prostate.

If your PSA is 3–10 ng/mL your doctor may suggest a DRE. If the DRE is normal and you have no symptoms, they may just do a repeat PSA test. If you are at high risk, they will usually suggest a urine biomarker test and mpMRI.

MRI scan

An MRI (magnetic resonance imaging) scan uses a powerful magnet and radio waves to build up detailed pictures of the inside of the body. A specialised MRI called mpMRI (multiparametric magnetic resonance imaging) is used to look for prostate cancer. It combines the results of a number of MRI images to provide a more detailed image.

Your urologist will suggest an mpMRI if there are concerns about your PSA results, symptoms or risk factors – or sometimes after a DRE. An mpMRI may also be used to see if you need a biopsy or to guide the biopsy needle to a specific area of the prostate. It may also show if cancer has spread from the prostate to nearby areas.

Before the scan, let your medical team know if you have a pacemaker or any other metallic object in your body, as the magnet can interfere with some pacemakers. Newer pacemakers are often MRI-compatible.

Having an MRI

Sometimes a dye (called contrast) is injected into a vein before the scan to help make the pictures clearer. You then lie on an examination table that slides into the scanner – a large metal cylinder open at both ends.

The scan is painless, but the scanner makes loud noises and is narrow, which makes some people feel anxious or claustrophobic. If you think you could become distressed, mention this beforehand to your medical team. You may be given a mild sedative to help you relax. You will have ear plugs or headphones. The MRI scan may take around 30 minutes.

Biopsy

Depending on the results of an mpMRI scan, your urologist may sometimes suggest a biopsy to remove tissue samples from the prostate. They will explain the risks and benefits and give you time to decide if you want to have one. If the mpMRI scan shows your doctor enough information, they may suggest you do not need a biopsy.

There are 2 main ways to perform a prostate biopsy, both of which are normally done under general anaesthetic:

• transperineal (TPUS or TPB) biopsy – a small ultrasound probe is inserted into your rectum. An image of the prostate appears on a screen and helps guide a needle, which is inserted through the skin between the anus and the scrotum
• transrectal (TRUS) biopsy – the needle is inserted into the prostate via the rectum.

During either procedure, the doctor may take a number of samples from different areas of the prostate and also remove a sample from any suspicious areas seen on the mpMRI.

Side effects

Depending on the type of biopsy you have, after the procedure you may see a small amount of blood in your urine or bowel movements (poo) for a few days, and blood in your semen for a couple of months. After a TPUS biopsy, the risk of infection is extremely low. There is a greater risk of infection with a TRUS biopsy, but the risk is still low. Your doctor may suggest taking antibiotics before or after a biopsy if they think you may be at risk of infection.

The biopsy samples are sent to a laboratory, where a specialist doctor called a pathologist looks for cancer cells in the tissue. Waiting for the results can be stressful. For support, call Cancer Connect on 13 11 20.

Further tests

If the mpMRI or biopsy results show prostate cancer, other tests may be done to work out whether the cancer has spread.

PSMA PET–CT scan

A PET (positron emission tomography) scan combined with a CT scan is a specialised imaging test. A PET–CT scan may be used to help detect cancers, or to find cancer that has spread or come back. The scan usually looks for a substance produced by prostate cancer cells called prostate specific membrane antigen (PSMA). Before the scan you will be injected with a small amount of a radioactive solution that makes PSMA show up on the scan. A Medicare rebate is available for newly diagnosed patients with intermediate or high-risk prostate cancer.

Bone scan

This scan can show if prostate cancer has spread to your bones. A tiny amount of radioactive dye is injected into a vein. You wait for a few hours while the dye moves through your bloodstream to your bones. The dye collects in areas of abnormal bone growth. Your body will then be scanned with a machine that detects the dye. A larger amount of dye will usually show up in any areas of bone with cancer cells. The scan is painless and the radioactive dye passes out of your body in a few hours.

CT scan

A CT (computerised tomography) scan uses x-rays to create detailed pictures of the inside of the body. A CT scan of the abdomen (belly) 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 large, round doughnut-shaped scanner. The scan itself takes a few minutes and is painless, but the preparation takes 10–30 minutes.

Which scan will I have?

A large clinical trial conducted in Australia, the proPSMA trial, showed that for certain men with newly diagnosed prostate cancer, a PSMA PET–CT scan is more accurate than having traditional CT and bone scans. A Medicare rebate was introduced in 2022, meaning about 75% of all newly diagnosed prostate cancer patients in Australia will be offered a PSMA PET–CT instead of a CT and bone scan.