Prostate cancer Specific Antigen PSA
Prostate cancer is the most frequent type of cancer found in the man and the second cause of death due to the cancer in man. Prostate cancer incidences increase dramatically in males with an age over 40 years, occurring in 50% of those over 70 years. Compared to other cancers, prostate cancer is more successfully treated if diagnosed early. Recently, another prostate enzyme has been identified and purified, which specific for prostate tissue, normal or malignant, and also found in periurethral glands. This enzyme is called prostate specific antigen (PSA). Looking at PSA from the biological side, it is a 33 kDa protein that is synthesized in the prostatic gland. It :functions as a serine protease and serves to liquefy the seminal fluid. As demonstrated by immunohistological studies, PSA is localized in the cytoplasm of prostate acinar cells, ductal epithelium and in the secretion on the ductal lumina, present in normal, benign hyperplastic and malignant prostate tissues as well as in metastatic prostate cancer and in seminal fluid. An elevation of the serum concentration is reported in patients with both benign prostatic hypertrophy prostate carcinoma, but rarely in healthy men and is absent in normal women. PSA is not present in any other normal tissue obtained from men, nor is it produced by cancers of the breast, lung, colon, rectum, stomach, pancreas and thyroid. The PSA level in serum or plasma of normal health men should be lower than 4 ng/ml, so the reference line is designed to be approximately the intensity of I 0 ng/ml. If the structural integrity of the prostate is disturbed and/or the gland size is increased, the amount f PSA in the blood serum/plasma may become elevated, reaching levels up to 200 ng/ml PSA. At a cut-off of 4 ng/ml PS.A, further medical analysis is recommended, although at a concentration range between 4-10 ng/ml PSA the elevated levels are commonly not caused by cancer but by other factors like benign prostatic hyperplasia or prostatitis. Plasma concentrations of >10 ng/ml PSA strongly indicate the presence ofprostatic carcinoma. Although a race- and/or age-dependent modification of the cut-off has been discussed in the literature, the amount of 4 ng/ml PSA is the generally accepted value at which follow-up examinations of the patient should be started.