Prostate cancer: The role of PSA and MRI in screening

For over 25 years, prostate cancer screening has been based on a digital rectal exam (DRE) undertaken in association with a prostate-specific antigen (PSA) blood assay. In recent years, magnetic resonance imaging (MRI) has been increasingly used to confirm PSA test results and determine which patients will benefit from a prostate biopsy and any subsequent treatments.

PSA is a protein in the blood exclusively derived from the prostate. Depending on age, blood levels below 3 or 4 nanograms per millilitre (ng/mL) are considered safe. Levels between 4 and 10 ng/mL are seen in both cancer and benign prostate disorders, including benign prostatic hyperplasia (BPH) and acute prostatitis. Levels above 10 ng/mL are generally associated with cancer and can be used to estimate disease progression. It is also important to remember that PSA levels are completely normal in almost 15% of prostate cancers.[3]

Men at an intermediate risk of prostate cancer should consider an initial PSA test as of age 50. In the case of men who are at a higher risk (African or Caribbean ancestry, family risk), we are looking at 45 years of age.

Magnetic resonance imaging (MRI) of the prostate is a non-invasive exam. It involves creating a strong magnetic field around the prostate and then emitting radio waves to produce very high-precision images of the prostate and the surrounding tissues in 2 or 3 dimensions. MRI is often performed after injection of a contrast agent such as gadolinium.[4]

A diagnosis of prostate cancer is confirmed by microscopic analysis of the biopsy sample. In fact, many benign prostate disorders such as acute prostatitis and BPH are sometimes difficult to distinguish from cancer. Moreover, not all cancers are equally dangerous; some progress so slowly that that they are unlikely to cause health problems before death from another cause. A biopsy can identify the most dangerous types of cancer, localized infiltration or involvement and, in conjunction with other techniques, the presence of metastases.

PSA testing in asymptomatic men without specific risk factors is known to generate a high number of anxiety-inducing abnormal results that can lead to unnecessary and sometimes dangerous interventions. It is estimated that three-quarters of PSA test results ranging from 4 to 10 ng/mL are not attributable to cancer and are, instead, indicative of a benign prostate disorder that does not warrant a biopsy.[2] A study published in December 2022 in the prestigious New England Journal of Medicine showed that MRI prior to biopsy halved the number of unnecessary biopsies in 17,980 Swedes with PSA levels greater than 3 ng/mL at the expense of a slight reduction in the detection of intermediate-risk cancers.[5]

As with all cancers, the earlier prostate cancer is detected, the greater the chances of survival. Fortunately, we have at our disposal a number of methods, including the combined use of PSA testing and MRI, to detect the cancer early before it progresses. It is important to discuss the advantages and disadvantages of prostate cancer screening with your healthcare professional before an initial PSA test.

We offer services that can help your doctor screen for prostate cancer and determine the appropriate next steps.

• Magnetic Resonance Imaging (MRI)
• Prostate-specific antigen (PSA)

Book an appointment online or contact Biron Health Group customer service at 1 888-937-1579 for Imagix services or 1 833-590-2712 for Biron Medical Laboratory services.