Summary

• PSA, or prostate specific antigen, is made by the prostate.
• Small amounts leak into the bloodstream.
• If you have prostate cancer, it is likely that more PSA will get into the bloodstream than normal.
• Measuring PSA can help in diagnosing and monitoring prostate cancer.
• However, many other non-cancerous conditions as well as activity and medications can cause PSA levels to rise.
• This means PSA results cannot be used by themselves to diagnose prostate cancer.

What is PSA?

PSA is a protein made by the prostate cells. Its job is to liquefy semen. Small amounts leak into the bloodstream where it can be measured. In most prostate cancer, more PSA gets into the blood than normal. However, other non-cancerous conditions, activity and medications can also cause PSA levels to rise.

PSA is measured to screen for prostate cancer, and to monitor the response to treatment in people who have prostate cancer. Rises in PSA levels can be caused by many factors and are not always due to prostate cancer. The PSA test cannot specifically test for cancer and can only show changes happening in the prostate. By itself it cannot diagnose prostate cancer.

Two forms of PSA

PSA exists in two forms in the blood:

1. free (not bound)
2. complexed (cPSA, bound to other blood proteins).

The most common test is the total PSA which measures the sum of both. When a doctor orders a PSA test, they are referring to a total PSA test.

Free PSA is sometimes ordered when total PSA levels are only slightly raised. This is to try to differentiate between prostate cancer and non-cancerous conditions.

Why get tested?

Raised levels of PSA are associated with prostate cancer, but they are also seen with prostatitis (inflammation of the prostate) and benign prostatic hyperplasia (BPH) (a big or enlarged prostate). Levels tend to increase in all men as they age.

The Urological Society of Australia and New Zealand Position Statement on PSA Testing from September 2022 (which is under review) recommended:

• PSA testing can be offered to men at an elevated risk of having prostate cancer. These include men more than 45 years of age with a family history of prostate cancer, men of high-risk ethnicities (including Indigenous men) more than 45 years of age and men carrying BRCA2 mutations more than 40 years of age.
• PSA testing in men who are likely to live less than another 7 years is not recommended.

BPH – benign prostatic hyperplasia

Two-thirds of men who see their doctor with high PSA levels have non-cancerous conditions. BPH is a non-cancerous swelling of the prostate that mostly occurs in older men. Because the prostate gland tends to get bigger with age, it can squeeze the urethra and cause problems in passing urine.

Prostatitis

This is inflammation of the prostate usually caused by an infection, most often when bacteria spill into the prostate from the urinary tract. It can be acute – it comes on suddenly for a short time - or chronic which means it is on-going. People with prostatitis often have other symptoms such as discomfort and tenderness. Prostatitis is treated with antibiotics.

Many things can cause temporary rises in PSA levels. This includes anything that disturbs the prostate such as riding a bike or motorbike, vigorous exercise, having a rectal examination, an orgasm within the past 24 hours or prostate surgery. Some medications are known to raise levels.

Since prostate cancer shares similar symptoms with many other conditions, your doctor may order other tests, such as a urine culture. If a total PSA level is raised, they may order a repeat test a few weeks later to see whether the PSA levels have returned to normal.

Should you get tested?

Prostate cancer is the most commonly diagnosed cancer in men and the second most common cause of death from cancer in Australian men, with indigenous men having a higher rate of prostate cancer mortality. The Australian Government Position Statement on PSA testing recommends offering testing from the age of 50 years to men who have been informed of the risks and benefits of PSA testing for prostate cancer.

There is a lot of conflicting advice about PSA testing. However, long term data on PSA screening for prostate cancer has shown that there is a survival advantage from PSA testing. So before getting a PSA test, talk to your doctor about the benefits and risks of having this test. Then you can decide if you wish to go ahead or not.

Genetic testing for prostate cancer

Prostate cancer is highly heritable. It is estimated that up to 60 per cent of prostate cancer risk is caused by inherited factors. This is due to many genetic alterations, called variants, that are common in the general population. The more of these common variants a person has, the greater the risk of prostate cancer. As well as this, some less common genetic variants can confer an even greater risk of prostate cancer. About 1–2 per cent of prostate cancers are due to disease-causing variants in the BRCA1 and BRCA2 genes. Genetic testing for prostate cancer gene variants is available in genetic pathology laboratories across Australia for men with a family history of the disease. Environmental factors also contribute to this risk.

Having the test

Sample

Blood

Preparation

You may be advised to avoid ejaculation and vigorous physical activity affecting the prostate, such as bicycle riding, during the two days before the blood test. The sample should also be collected before the digital rectal exam and before (or several weeks after) a prostate biopsy.

Your results

Reading your test report

Your results will be presented along with those of your other tests on the same form. You will see separate columns or lines for each of these tests.

For men with an initial PSA level of more than 3 µg/L, your doctor will consider the need for further testing that may including an MRI scan and prostate biopsy.

A sudden increase in total PSA levels suggest prostatitis.

Some cancer cells do not produce much PSA, so it is possible to have a normal result yet have cancer. Recent studies have shown that there is still a small risk of prostate cancer, even if blood PSA levels are normal for age.

PSA levels can vary, so your doctor may decide to repeat the test to compare your results over time.

The only definite way to confirm whether prostate cancer is present or not is by prostate biopsies (taking small samples of tissue).

PSA ratio

The PSA ratio, or free-to-total PSA ratio, is used when total PSA levels are between 4.0 and 10.0 ug/L to distinguish between benign conditions and prostate cancer. The test measures the amount of free PSA versus total PSA in your blood. Free PSA is not bound to proteins. A lower ratio (below 10-15 per cent) suggests a higher chance of prostate cancer, while a higher ratio indicates benign conditions like benign prostatic hyperplasia (BPH).

Reference Intervals

Your pathology laboratory will report your results compared to reference intervals (sometimes called a normal range).

• Reference intervals are the range of results expected in healthy people. However, your doctor will advise you on follow up based on your PSA level.
• When compared against them your results may be flagged high if they sit outside this range.
• Many reference intervals vary between labs so only those that are standardised or harmonised across most laboratories are given on this website.

If your results are flagged as high or low this does not necessarily mean that anything is wrong. It depends on your personal situation. Your results need to be interpreted by your doctor.

Follow-up tests

Prostate biopsy: If you have a result higher than the PSA recommended cut-off level, your doctor may arrange for you to have a biopsy. This is a surgical procedure that takes small pieces of tissue from different parts of the prostate. The samples are sent to the lab where they are processed and looked at under a microscope. A pathologist specialising in tissue investigates the prostate cells for cancer and sends a report to your doctor. They provide information on whether you have cancer, the type of cancer and whether or not it is aggressive.

Scans: If cancer is detected, you may need to have imaging tests such as MRI, CT or bone scans to see if the disease is contained to the prostate or if it has spread, and to help with management and treatment decisions.

More to know

You may come across the following terms:

• PSA Density – the relationship of the PSA level to the size of the prostate measured by ultrasound examination.
• PSA Velocity – how quickly PSA levels change over time.
• PSA Doubling Time – the time it takes for the PSA value to double. This may be useful in following treatment and determining the type of treatment.

Questions to ask your doctor

The choice of tests your doctor makes will be based on your medical history and symptoms. It is important that you tell them everything you think might help.

You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.

Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods, medications or supplements. These may affect your results. Ask:

• Why does this test need to be done?
• Do I need to prepare (such as fast or avoid medications) for the sample collection?
• Will an abnormal result mean I need further tests?
• How could it change the course of my care?
• What will happen next, after the test?

More information

Pathology and diagnostic imaging reports can be added to your My Health Record. You and your healthcare provider can now access your results whenever and wherever needed.

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