Description
Prostate-specific antigen, or PSA, is a protein produced by normal, as well as malignant, cells of the prostate gland. The PSA test measures the level of PSA in a man’s blood. For this test, a blood sample is taken for analysis. The results are usually reported as nanograms of PSA per milliliter (ng/mL) of blood.The blood level of PSA is often elevated in men with prostate cancer. PSA test in conjunction with a digital rectal exam (DRE)is used to test asymptomatic men for prostate cancer. Men who report prostate symptoms often undergo PSA testing (along with a DRE) to help doctors determine the nature of the problem.
In addition to prostate cancer, a number of benign (not cancerous) conditions can cause a man’s PSA level to rise. The most frequent benign prostate conditions that cause an elevation in PSA level are prostatitis (inflammation of the prostate) and benign prostatic hyperplasia (BPH) (enlargement of the prostate). There is no evidence that prostatitis or BPH leads to prostate cancer, but it is possible for a man to have one or both of these conditions and to develop prostate cancer as well.
In men over 50 years with total PSA between 4.0 and 10.0 ng/mL, the percent (%) free PSA gives an estimate of the probability of cancer. In these circumstances the measurement of the % free PSA may aid in avoiding unnecessary biopsies.a free:total PSA ratio =0.10 indicates 49% to 65% risk of prostate cancer depending on age; a free:total PSA ratio 0.25 indicates a 9% to 16% risk of prostate cancer, depending on age.
Elevated levels of Prostate Specific Antigen (PSA) have been associated with benign and malignant prostatic disorders. In addition, PSA decreases to undetectable levels following complete resection of the tumor and may rise again with recurrent disease or persist with residual disease. Thus, PSA levels may be of assistance in the management of prostate cancer patients.
PSA, a protein produced by prostate gland cells, circulates through the body in two ways: either bound to other proteins or on its own. PSA traveling alone is called free PSA. The free-PSA test measures the percentage of unbound PSA; the PSA test measures the total of both free and bound PSA.
Prostate cancer can raise PSA levels, but so can other conditions. These include an enlarged prostate, prostatitis, and advancing age. In fact, studies have shown that about 75% of men with an elevated PSA do not have prostate cancer. To determine which men actually have cancer and which don’t, physicians traditionally perform a biopsy. Undergoing a biopsy isn’t as traumatic as surgery, but it does cause discomfort and can provoke anxiety.
Rather than subject everyone with an elevated PSA to a biopsy, some urologists measure free PSA in patients with a total PSA level between 4 ng/ml and 10 ng/ml. Studies have shown that men with a total PSA in this “gray area” and a free PSA greater than 25% are more likely to have a benign condition than to have cancer, making a biopsy unnecessary. Men with a total PSA in the same range and a free PSA below 10% need to have a biopsy. More likely than not, they have prostate cancer.In some cases, men with a “normal” PSA actually have cancer, but that low PSA doesn’t prompt a biopsy. A low PSA and a low percentage of free PSA, however, probably would. That’s why sometimes both tests are ordered at the same time.
