Prostate cancer is unfortunately one of the most common cancers in men. Fortunately, modern medicine now has powerful tools to detect, monitor, and better treat it. Two terms often come up: PSA (prostate-specific antigen) and PSMA (prostate-specific membrane antigen).

Although their names may sound similar, these two markers have very different—and complementary—roles. This article will help you understand:

• The role of PSA and what an abnormal level may indicate
• The role of PSMA and how it helps visualize cancer cells
• The differences between PSA and PSMA

Medical review by uro-oncologist Dr. Nawar Hanna, December 2025

PSA: a warning marker in the blood

As a screening tool

PSA, or prostate-specific antigen, is a protein naturally produced by the prostate. Its primary role is to help fluidify semen, but small amounts are also present in the blood.

When the prostate is affected by inflammation, benign enlargement (such as benign prostatic hyperplasia), or cancer, PSA levels in the blood can rise.

This is why a simple blood test measuring PSA is often the first test a doctor recommends to monitor prostate health. However, it is important to remember that:

• A high PSA level does not necessarily mean cancer
• Cancer can exist even with a normal PSA level

In other words, PSA acts as a warning signal but is not a diagnosis on its own. It must be interpreted alongside other exams, such as a digital rectal exam, MRI, or biopsy, depending on the doctor’s recommendations.

As a monitoring tool during and after treatment

During treatment, PSA levels are measured periodically to assess how well the cancer is responding.

After treatment—whether surgery, radiation, or hormone therapy—PSA levels should decrease and stabilize. Later, repeated increases in PSA may indicate a recurrence, potentially requiring additional treatment.

PSMA: both a target and a treatment

A highly specific cancer target

PSMA (prostate-specific membrane antigen) is a protein found on the surface of prostate cells. Its usefulness lies in the fact that prostate cancer cells produce much more of it, especially in aggressive or advanced forms of the disease.

Thanks to this property, doctors can now locate cancer cells with high precision using advanced imaging: PSMA PET scans.

How it works

A radioactive tracer is injected into the body and binds to cells that express PSMA. The images obtained show exactly where tumors are located, even very small metastases that a CT scan or MRI might miss.

This exam is particularly useful:

• In cases of recurrence after treatment
• When PSA is elevated but other tests are normal
• To assess the extent of cancer before choosing a treatment

PSMA in treatment: targeted radiotherapy

PSMA is not only used for detection—it can also help treat cancer. Certain drugs, such as those containing Lutetium-177, specifically bind to PSMA-expressing cells. These treatments deliver a small dose of radiation directly to the tumor without damaging surrounding healthy tissue.

This approach, called targeted radioligand therapy, is very promising and offers real hope, especially for advanced cancers that no longer respond to traditional treatments.

PSA vs PSMA: key differences

Conclusion

PSA and PSMA are not competitors and cannot be used interchangeably. They play distinct roles at different stages of care. PSA is often the starting point to detect and monitor possible abnormalities. PSMA acts as a precise guide, helping visualize and treat cancer cells more accurately.

If you are concerned about advanced or metastatic prostate cancer, or if you simply want to better understand your options, speak with your doctor. They can guide you toward the most appropriate tests or treatments for your situation.

At PROCURE, we believe that better understanding leads to better living with the disease. Our professionals are here to support you and answer your questions, seven days a week. Contact us at 1-855-899-2873 or visit our website procure.ca