TOTAL PSA

Prostate cancer is the most frequent type of cancer found in
man and is the second cause of death due to cancer in
males. Until recently, digital rectal examination (DRE) was
frequently used as only diagnostic modality for the detection
of early stages of prostate cancer. In the recent years the
determination of serum PSA levels has become the most
accepted method to improve the diagnostic specificity of
DRE. Although PSA is a tissue specific protein and is not
solely tumor specific, it has become the most important
marker for prostate carcinoma, showing a better specificity
than other biochemical markers used in this context (PAP,
total alkaline phosphatase, carcinoembryonic antigen, etc.).
In 1979, Wang et al isolated a specific antigen for normal
prostate tissue and called this protein PSA. 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 metastatic prostate cancer and in
seminal plasma. If the structural integrity of the prostate is
disturbed and/or the gland size is increased, the amount of
PSA in the blood plasma may become elevated. An
elevation of PSA levels to values higher than 3-4 ng/ml has
been reported for patients with either benign prostatic
hypertrophy (BPH) or prostate carcinoma. At this threshold
follow-up examinations that allow to differentiate between
these two conditions are recommended.
The determination of PSA serum levels is not only important
for the screening of patients for prostate cancer, but also for
monitoring patients that have been treated for this disease.
Here regular PSA measurements are an important tool to
examine the potential and actual effectiveness of surgery or
other therapies. An increase of PSA in patients after radical
prostatectomy or radiotherapy may allow an earlier
discovery of residual or recurrent carcinoma.