PSA TEST: "CAP" College of American Pathologists

PSA Testing In The Early Detection, Diagnosis and Monitoring   of Prostate Cancer

Ported March 19, 2010 Policy Synopsis Application of Prostate-specific antigen (PSA) as a screening test is controversial because its sensitivity and specificity for cancer are poor, and because in some cases of slow growing prostate cancer early detection and treatment may have little benefit. It is, however, reasonable to offer PSA screening to most men aged 50 and older, and at an earlier age for African-American men and men with one or more first degree relatives with prostate cancer. PSA testing is useful in diagnosing patients who present with prostatic symptoms and in the investigation of a nodule detected by digital rectal examination. It is also useful as a monitoring tool for detecting recurrence or recognizing metastasis in a patient with prostate cancer. For monitoring and serial screening purposes, the same PSA assay method should be used for each measurement. Policy Prostate-specific antigen (PSA) is a protein found in serum that is derived almost entirely from prostatic glandular tissue. PSA measurement is used as a monitoring test to detect local recurrence or metastasis in patients with established prostate cancer (adenocarcinoma). PSA is also used to investigate patients who present with prostatic symptoms and signs and also for asymptomatic patients being screened for prostatic cancer. Screening The American Cancer Society, the American Urological Association, and the National Comprehensive Cancer Network have issued detailed advice regarding use of PSA for screening. The CAP is in general agreement with their information but does not endorse any specific screening policy. Application of PSA as a screening test is controversial for two reasons: 1) PSA levels are increased in prostate cancer, prostatitis and benign enlargement of the prostate; therefore sensitivity and specificity for cancer are poor. Some aggressive tumors elevate PSA only slightly, particularly in young African-American men. Cancer detection may be improved to some extent by using age-adjusted cutoffs, PSA “density”, PSA ”velocity”, and fraction of free or complexed PSA. * 2) Some prostate cancers are so indolent that early detection and treatment may have little benefit and potential for significant morbidity. At present, these cancers cannot be clearly distinguished from cancers that are more aggressive. It is reasonable to offer PSA screening to men of age about 50 or older, and at an earlier age for African-American men and men with one or more first degree relatives with prostate cancer. For a man in poor health with serious medical illness and/or a man who is unlikely to live for more than 10 years, there may be no benefit to the early detection of prostate cancer. PSA testing may actually do more harm than good since prostate cancer investigation and treatment can seriously affect one's quality of life. Men who are being offered PSA screening should be informed about the limitations of PSA testing and the consequences of an abnormal result. PSA testing should be performed by accredited laboratories applying rigorous quality control, because small analytic changes can cause inappropriate patient care decisions. Different PSA assay methods can yield different results. Accordingly, for monitoring and serial screening purposes, it is important to use the same PSA assay method for each measurement, and preferably in the same laboratory. Efforts to improve the agreement of commercial PSA tests should continue. Diagnosis PSA is a useful test in patients presenting with prostatic symptoms and in the investigation of a nodule detected by digital rectal examination. Elevated PSA measurements or rising PSA values in a patient with suspected prostate cancer may be followed up with a prostate biopsy. Evaluation of prostate tissue by a qualified pathologist is required for the diagnosis of prostate cancer. Monitoring PSA is a clearly useful test for detecting recurrence or recognizing metastasis in a patient with prostate cancer. The test should be performed periodically in patients who have received any type of treatment for prostate cancer including those on watchful waiting protocols. It is important that the laboratory measurements be made with assays, which have adequate sensitivity, to monitor patients who have had their prostate glands surgically removed and that clinicians preferably utilize the same laboratory for serial measurements. The time interval over which the concentration of PSA doubles in these men is an important indicator of progression of prostate cancer. * Definitions: PSA “density” is determined by dividing the PSA level by the volume of the prostate gland as determined by transrectal ultrasound - the higher the PSA density, the greater the likelihood of cancer. PSA “velocity” is the increase in PSA level occurring over a period of time. The measurement of PSA velocity should be made on three specimens taken over at least an 18-month period. A PSA velocity over 0.75 ng/mL per year is considered high. Free PSA indicates how much PSA circulates alone or unbound in the blood where as complexed PSA indicates how much PSA is bound together with other blood proteins. For PSA results between 4 and 10, a low percent free PSA means that a prostate cancer is more likely to be present. Revision History Adopted March 2004 Revised February 2010