PSA EXPLANATION IN PATIENTS WITH PROSTATE CANCER

What is PSA, and how do we measure it?

PSA stands for Prostate Specific Antigen and is a blood test that is used to screen for the presence and amount of prostate cancer. More accurately, the PSA is found in the blood's serum, which is the fluid that the red blood cells and white blood cells travel.

An antigen is a medical or biological term for a substance or protein that stimulates the body to make antibodies.

Prostate Specific Antigen is a protein found in the serum that is unique or specific for the prostate, both normal prostate and prostate cancer cells. In the case of prostate cancer, the PSA will reflect the presence of the tumor, wherever the cancer cells are present in the body. No other tissues or body parts can make Prostate Specific Antigen. Therefore, the PSA levels can be measured in an individual's serum and with this information we are able to follow prostate cancer.

What is the significance of the PSA if I have prostate cancer?

If a diagnosis of prostate cancer has been made by biopsy, then the PSA level can be used as a marker for the treatment of prostate cancer. If the prostate gland is removed (Radical Prostatectomy) we expect the PSA level to be unmeasurable (less than 0.1). If any PSA is measured after Radical Prostatectomy, then the presence of prostate cancer cells somewhere in the body has to suspected.

Prostate cancer cells that have spread to other areas also make Prostate Specific Antigen. Even if we cannot find the areas of spread with scans or other tests, the presence of PSA means that the cancer is present. If the treatment of the cancer was with any form of radiation, chemotherapy or hormone therapy, the PSA level will not necessarily become unmeasurable. The normal prostate cells may not be destroyed and may still leak normal amounts of PSA. However, the PSA level should be stable if the treatment is working. That means a rising PSA level suggests growth of the cancer.