Also Known As:  Acid Phosphatase, Prostatic, PAP

Prostatic acid phosphatase has been used as a tumor marker ever since the observation by Gutman in 1938 that elevated levels of this enzyme are found in patients with metastatic prostate cancer. PAP determination in conjunction with PSA measurements is useful in assessing the prognosis of prostate cancer. Measurement of two markers allows identification of prostate cancer patients who have an elevation of PAP but not of PSA, and thus help monitoring the course of disease and response to treatment. PAP is more specific than PSA and less false-positives are seen due to benign prostatic hyperplasia.