Health Library

PSA Test

Doctors have been using a PSA blood test to screen men for prostate cancer for many years.  Although Akumin does not actually perform this particular test, it is an important element of the overall screening process and is usually the first step prior to additional screening exams such as prostate MRI and prostate ultrasound that are performed at Akumin clinics.

Overview 

PSA stands for prostate-specific antigen. This marker is measured via a blood test and primarily helps screen for prostate cancer.

PSA is a protein produced by the tissues in the prostate, which is a gland present just below the bladder in men. The protein is produced by both benign and malignant tissues, making it difficult to diagnose cancer with just this marker accurately.

PSA can be found in various body fluids. The highest percentage is found in semen which is produced in the prostate. Small quantities of the protein may also be found circulating in the blood.

The test detects typically high levels of PSA in the circulation. But you must note that prostate cancer is not the only medical condition that can raise PSA levels. Inflammation and subsequent enlargement of the gland can also produce similar results, making an accurate diagnosis a difficult feat.

Why it’s done

Prostate cancer is a common malignant condition affecting males worldwide and is also responsible for multiple cancer-related deaths. As is the rule, early detection could be your golden ticket to a full recovery with any malignancy.

While prostate cancers may elevate PSA levels, other non-cancerous conditions may also lead to a similar increase. Therefore, the PSA test aims to notify patients of some abnormality in the prostate but does not provide a precise diagnosis of the condition.

Due to its lack of sensitivity and specificity for diagnosing a disease, the PSA test is often used as a screening test for early detection of prostate cancer. It is usually combined with the digital rectal exam, another standard screening modality.

Your doctor aims to reach your prostate via the rectum in a digital rectal examination. Therefore, he or she will insert a lubricated, gloved finger into the rectum, apply pressure on the prostate and check for any abnormal masses or hardness.

The biggest drawback of both these tests is that they do not provide sufficient information for your doctor to diagnose prostate cancer. If they find an abnormality in these test results, they may request you to undergo a prostate biopsy.

The procedure is generally performed under anesthesia; wherein tissue samples are removed and sent for microscopic and laboratory examination. A prostate biopsy is perhaps the most sensitive test for detecting prostate cancer.

Other reasons for PSA tests

If a male has already been diagnosed with prostate cancer, the PSA test may still be used for the following –

  1. To determine the prognosis of the disease
  2. To assess the effectiveness of the treatment
  3. To check for relapse of the malignancy

Benefits of the test

One of the PSA tests benefits is that they can detect prostate cancer at an early stage, which can drastically improve the prognosis and outcome of the disease. It contributes to lower mortality caused due to prostate cancer.

However, one major issue with this cancer is that it is a slowly progressive disease and may produce symptoms only after it has progressed to a much higher stage. Some prostate cancers may not produce symptoms at all. Since the PSA test is not a routine examination, it may not always contribute to early diagnosis.

Limitation of the test

Some of the disadvantages and limitations of the PSA test include –

  • PSA-raising factors – Malignancy is not the only condition that raises PSA levels. Enlargement of the prostate in diseases such as benign prostatic hyperplasia (BPH) and infections such as prostatitis may also elevate PSA levels. Moreover, PSA levels also increase physiologically with age.
  • PSA-lowering factors – Certain pharmacological drugs used in treating BPH or urinary tract infections, urinary incontinence, and chemotherapy can lower PSA levels.
  • Inaccurate results – PSA levels are not the most sensitive markers for prostate cancer. Not all males with elevated PSA levels have prostate cancer, and not all males with prostate cancer have elevated PSA levels.
  • Overdiagnosis – There are several instances where prostate cancer detected by PSA test may not produce any symptoms throughout the lifetime of the patient. Providing treatment for cancer that is unlikely to affect health is known as overdiagnosis and must be avoided.

Potential risks 

Each investigation comes with its own set of risks. The potential risks of the PSA test depend upon the choices you make based on their results. For instance, if you decide to undergo further testing or begin treatment for prostate cancer, the risks could be as follows –

  • Biopsy – To confirm the diagnosis of prostate malignancy, a biopsy is essential. But it comes with its own set of risks, such as pain, bleeding, and post-biopsy infection.
  • Psychological effects – One of the most significant drawbacks of the PSA test is its false-positive results, where the high PSA levels are not caused due to malignancy. The uncertainty in diagnosis causes distress to the patients. Moreover, if you have prostate cancer, but it is a very slow-growing tumor, just acknowledging its presence may cause significant anxiety.

It is always best to discuss the advantages, disadvantages, and potential risks of the test with your doctor or healthcare provider to make an informed decision.

What you can expect

The PSA test is a simple blood investigation where the nurse or phlebotomist will use a needle to withdraw venous blood from your arm.

Results 

PSA levels are reported in nanograms of PSA per milliliter of blood (ng/ml). No specific cut-off value is currently used to determine abnormality in the PSA levels.

Variations of the PSA test

Since prostate biopsy can be quite painful, risky, and expensive, your doctor may use other ways to interpret your PSA levels report before requesting a biopsy. These variations of the test help improve the accuracy of the test results.

The variations of the PSA test include –

  • PSA velocity – PSA velocity traces the changes in PSA levels over time, which helps determine whether the tumor or disease has a quick and aggressive progression or is slow-growing. However, several studies have questioned the precision of PSA velocity for detecting prostate cancer compared to a biopsy.
  • Percentage of free PSA – PSA exists in the two forms in the bloodstream – an attached form and a free form. High PSA levels and low free PSA levels are typical findings in prostate cancer.
  • PSA density – PSA per volume of tissue is known as PSA density. Prostate cancers have more PSA density than benign conditions. To determine the PSA density, you generally require an MRI or transrectal ultrasound.

Talk to your doctor

Ongoing communication with your doctor is crucial before deciding to get a PSA test. You must carefully understand the benefits and risks of the test before making your decision. Also, confirm with your doctor about when you can discuss the results, what you can expect if the results are positive, and repeat the test in case of negative values.

Openly discussing such issues beforehand makes it easier for you to understand your results and make future decisions about your health.

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