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What is the PSA test?

November 15, 2021

Your complete guide to the PSA test – What it is, its history, the controversies/limitations around it and what the future holds for prostate cancer testing. 

One in six Australian men will be diagnosed with prostate cancer by the age of 85. In a normal year, 750,000 Australian men have the PSA (Prostate-Specific Antigen) test completed, as the initial means of testing for the disease. At a time when discussion around current prostate cancer screening guidelines is ramping up for several reasons, the PSA test take centre stage. 

To offer some context to these discussions, we wanted to provide you with a complete guide to the PSA test, which will include: 

What is Prostate-Specific Antigen?

Prostate-specific antigen, or PSA as it's more commonly known, is a protein produced by normal and malignant cells of the prostate gland, located at the base of a man's bladder. The protein is released into semen, but it is also known to enter the bloodstream. 

What is the PSA test?

The PSA test is used to measure PSA levels in a man's blood, which can help detect the presence of or monitor prostate cancer. A PSA test is just a simple blood test used to measure the nanograms of PSA per millilitre (ng/ml) of blood. 

High levels of PSA can be an indicator of prostate cancer, but they can also be caused by other conditions. Therefore, a PSA test can point clinicians in the right direction for further testing, but it is not a conclusive test capable of diagnosing prostate cancer. 

There are a number of derivates of the PSA that can also be used in aiding the diagnosis such PSA and Free-to-Total Ratio test and the Prostate Health Index. These are more advanced tests and are all used as part of Maxwell Plus’ diagnostic process

What is the history of the PSA test?

First used in Australia during the late 1980s, the PSA test has become a staple for monitoring clinically identified prostate cancer. 

Since 1996, PSA testing has been the primary method of testing for prostate cancer. However, PSA is not solely related to cancer, and therefore, is not used to diagnose cancer, rather to determine whether it could be there. 

While 750,000 men get the test, this is still less than 20% of the at-risk cohort, significantly less than bowel and breast cancer which have their own government sponsored screening program.

What are the controversies/limitations of the PSA test?

The PSA test has long been attached to controversy. Primarily because although the higher the PSA, the higher the chance of prostate cancer, there can be many other reasons for a man's PSA level to be high. 

Other factors such as the relative prostate size for the individual and recent sexual activity can also affect PSA levels. Meaning, the results from man to man have long been synonymous with false positives and instances of over-treatment of prostate cancer. 

Since 1996, several studies have been undertaken in which large groups of men were followed over decades to ascertain the effectiveness of PSA testing. Studies in Europe, the US and similarly here in Australia found that although the rate of death by prostate cancer reduces, a high risk of overdiagnosis closely follows. 

These trials ultimately culminated with the US Preventative Services Taskforce (USPSTF) stating in 2012:

"USPSTF recommends against prostate-specific antigen (PSA)-based screening for prostate cancer." USPTF May, 2012

Thankfully, since 2012, USPSTF has rewound its recommendation due to criticism, adopting the same stance as other agencies, including the Prostate Cancer Foundation of Australia (PCFA). Which is that, instead of forgoing a PSA test entirely, men should speak with their GP and discuss the potential benefits and harms of screening. 

And this is where it gets a little confusing. Where we currently sit, the PCFA recommends GPs offer

"evidence based decisional support to men considering whether or not to have a PSA test."

While the Royal Australian College of General Practitioners (RACGP) recommends GPs have no obligation to offer prostate cancer screening to asymptomatic men.

So, as it currently stands, GPs have no concrete mandate for what their role and advice should be. As a result, men are still dying from prostate cancer, and men and the medical community are confused as to what should happen for PSA testing.

This confusing stance and advances in technology has now brought us to today where men are still dying and PCFA, Maxwell Plus and experts a calling for a reinvestigation of guidelines.

Australia needs a government-sponsored prostate cancer screening program. One that takes into account new technology like AI and the information available courtesy of 10 or so more years of research, and progress to a more accurate and thorough mandate. 

What is the future of prostate cancer testing?

The future is already here. Clinicians have access to more advanced blood tests, which help determine the cause of a high PSA more accurately. These tests include the PSA with Free-to-Total Ratio, the Prostate Health Index (PHI), the PCA3 urine test, and the 4kScore, among others. 

All these tests help to develop a more accurate picture of prostate cancer risk. And when you combine them with new technologies for calculating risk, such as the AI Maxwell Plus has developed, doctors have highly comprehensive analysis at their disposal. 

In conjunction with the high availability of MRIs, this AI development can be the blueprint for a national screening program. These technologies enable us to develop stronger understanding, more detailed and comprehensive documentation, and new realms for research, enabling the medical community to quantify a man's risk more accurately than ever before.