PSA Tumor Marker

PSA stands for the so-called Prostate-Specific Antigen. This substance belongs among the most known tumor markers, i.e. substances, whose concentration in blood (or other body fluids) is elevated in certain malignancies. The primary use of PSA is in urology.

Principle

PSA is a protein that is produced by prostatic cells and it is secondarily released into the bloodstream. Like other tumor markers, the PSA can be examined from a sample of venous blood.

Indications

The primary use of PSA is  diagnosis of the prostate cancer. It is relatively accurate and helps us to distinguish, if the prostate is normal, enlarged (benign prostate enlargement), or if a prostate cancer is present. However, even extremely high level of PSA alone is not sufficient to diagnosis of prostate cancer and it must be followed by other examinations including physical exam, abdominal ultrasound and prostate biopsy.

 

In addition to the total PSA, we also distinguish the free PSA (fPSA). It is a component of PSA that is present in bloodstream freely without binding to any proteins. When the PSA is elevated, it is advisable to check the fPSA and its ratio to the total PSA. The lower is the result, the higher is the probability of prostate cancer.

Disadvantages

PSA is more accurate than other tumor markers, but nevertheless, it is not absolutely reliable. There are many non-malignant diseases and situations when the PSA is elevated. We can find PSA elevation in benign enlargement of the prostate, in prostatitis, and also in men who have recently underwent digital rectal examination or prostate biopsy.