PSA, or prostate specific antigen — a marker for prostate cancer, which allows to identify the disease in its earliest stages. First Naga PSA was found in 1979 in the seminal fluid, and a 1987 study of PSA is widespread in the diagnosis and establish the stage of prostate cancer. And as for monitoring and evaluating the effectiveness of treatment.
PSA is a chemical substance produced by the prostate epithelium to liquefy semen. Some of this substance penetratesblood. Normally the amount of PSA in the blood is not more than 4 ng / ml, and by some reports up to 3 ng / ml. Increasing the concentration of PSA in the blood is damaged tissue prostate and increase its permeability. For example, increased PSA levels observed in benign prostatic hyperplasia (BPH), inflammation of the prostate (prostatitis), traumatic injuries and cancer prostate. To find out the cause of an elevated PSA level using special methods for its determination. An increase in PSA levels above 4 ng / ml. necessary to conduct a thorough examination of the patient for the diagnosis of prostate cancer at an early stage of its development, because the vast majority of cases of cancer account for the so-called "gray area" in which the value of PSA is between 4 ng / ml to 10 ng / ml. With the high level of PSA in the mandatory biopsy should be performed prostate.
Typically, the tissue biopsy is conducted transrectal prostate (through the rectum) with ultrasound using a special gun and disposable needles.
Serum PSA is in two forms, some proteins associated with and uncoupled from them, a free PSA. Talking about the diagnosis of PSA determination means both of its forms. Thus, cancer prostate, increases the amount of bound and decreases of free PSA. But for certain types of cancer level PSA may remain unchanged, because cancer cells have lost the ability to secrete this substance. When prostate cancer level free PSA in serum is significantly higher than for prostate cancer. It is on this principle features of PSA based differential diagnosis of prostate cancer and benign prostatic hyperplasia.
Today, in the world there is a program of early diagnosis of prostate cancer, which includes:
- DRE prostate;
- transrectal ultrasound of the prostate;
- determine the level of prostate-specific antigen (PSA).