PSA Blood Test

PSA

Prostate-specific antigen (PSA) is a protein produced by the cells of the prostate gland in males. The main function of PSA is to liquefy the semen that carries sperm during ejaculation. A small amount of PSA is normally present in the blood of men, but elevated levels can be an indicator of various prostate-related conditions. The most well-known use of PSA is as a screening test for prostate cancer. However, it’s important to note that elevated PSA levels do not necessarily indicate prostate cancer. Other non-cancerous conditions, such as prostatitis (inflammation of the prostate) or benign prostatic hyperplasia (enlargement of the prostate), can also cause increased PSA levels.

Weighing the risks and benefits

The PSA test is a screening test for prostate cancer. Screening tests aim to find cancer in people before they have symptoms. Screening can help find cancers at an earlier stage, when they are possibly easier to treat. If prostate cancer is found early as a result of screening, it could seem like PSA testing would always be a good idea. However, it is important to understand the risks and benefits of testing to decide if it is right for you. The choice to do a PSA test is an individual decision that should be made after understanding the risks and benefits of testing.

Benefits of PSA testing:

• Can detect prostate cancer before you have any symptoms
• Can detect a fast growing cancer at an early stage, before it spreads to other parts of the body and becomes difficult to treat

Doctors are still studying whether PSA testing lowers the risk of death from prostate cancer. Current study results on the benefits of screening are conflicting, which is why the choice to do a PSA test should be a personal one.

Results from a large European study of prostate cancer screening found that men who had prostate-specific antigen (PSA) testing had a 20 percent lower chance of dying from prostate cancer after 13 years, compared with men who did not have prostate cancer screening (Hugosson et al., 2019). However, the study also showed that 781 men would need to prevent one death from prostate cancer (Schröder et al., 2014). This means that testing the general population involves many men getting tested, and a very small number benefitting.

Risks of PSA testing:

Inaccurate test results

There is a chance of a false positive test result with all screening tests. This means that your PSA level is elevated but no cancer is present. A false-positive test result may create anxiety for you and your family, or lead to additional invasive medical procedures with their own side effects, such as a prostate biopsy. As multiple factors can cause PSA levels to rise, false positive PSA test results are common; approximately 25% of people who have a prostate biopsy due to an elevated PSA level are found to have prostate cancer after biopsy (Lopez-Corona et al., 2007).

A false negative test result means that the PSA level is found to be normal when prostate cancer is present. Approximately 15% of individiuals with prostate cancer do not have elevated PSA levels (Prostate Cancer UK, 2021). A false negative test result may provide false reassurance that no cancer is present. If you are experiencing prostate-related symptoms despite a normal PSA level, always contact your GP. 

Overdiagnosis and overtreatment

Overdiagnosis means diagnosing a condition that would never pose a threat to your health or life. Overdiagnosis can lead to treatments that are not necessary and have their own side effects, known as overtreatment. This can result in an individual sustaining harms with no benefits from screening for a disease. Research estimates 23% 43% of prostate cancers that are diagnosed with PSA testing may never need to be treated and will not affect a man’s life expectancy (Sandhu & Andriole, 2012). This means that many men die “with” prostate cancer, rather than “from” prostate cancer. However, most men who are diagnosed with prostate cancer understandably want to pursue treatment. Unnecessary testing and treatment can cause side effects such as incontinence, pain, and erectile dysfunction.

An elevated PSA level alone does not cause symptoms. However, if you are experiencing symptoms that indicate problems with the prostate, you may consider doing a PSA test. Potential symptoms include:

• Difficulty urinating
• Urinary incontinence
• Slow urine stream
• Frequent urination

What do the test results mean?

This test measures the PSA level in your blood. The results of this test cannot specifically tell you if you have prostate cancer.

There is no specific normal or abnormal PSA level in the blood.

• Generally, a PSA level of less than 4.0 ng/mL is considered normal. For dry blood spot testing methods, a normal PSA level is less than 4.4 ng/mL.
• A PSA level between 4.4 and 10.0 ng/mL is considered to be the “borderline range” in which the risk of prostate cancer is higher.
• A PSA level higher than 10.0 ng/mL indicates a greater than 50% chance of prostate cancer.

Please note: While a PSA test can be used to help detect prostate cancer, it is not perfect. Some cases of prostate cancer do not cause high PSA. It is also possible to have high PSA and not have prostate cancer. If you are experiencing symptoms consistent with prostate cancer, always contact your GP for further examination regardless of PSA level.

Factors such as age, prostate enlargement/inflammation, cycling, and recent ejaculation can also increase PSA levels. Furthermore, certain drugs can lower PSA levels. Recent research has suggested the following lower PSA limits for each age group:

40 – 49 years :  2.50 µg/l

50 – 59 years :  3.50 µg/l

60 – 69 years :  4.50 µg/l

70 – 79 years :  6.50 µg/l

In combination with your PSA test result, ask your GP about the possibility of a prostate exam to confirm there are no abnormalities.

What should I do if my test result shows elevated PSA?

If your blood PSA is higher than normal, it doesn’t always mean you have prostate cancer. Many men with elevated PSA do not have cancer. Please take your test result to your doctor for further investigation. Further testing may include:

• Waiting a while and taking a second PSA test to see if levels have changed
• Getting another type of PSA test (such as free PSA) to check if a prostate biopsy is needed
• Physical prostate exam
• Prostate biopsy