Prostate-specific antigen (PSA) is a protein produced by cells of the prostate gland that can be detected in blood. Blood PSA levels typically rise in men who have prostate cancer. Since the 1990s, the PSA test has been used, along with the digital rectal exam (DRE), to regularly screen men over age 50 for prostate cancer.
The trouble is, noncancerous prostate conditions such as prostatitis (prostate inflammation) and benign prostatic hyperplasia (BPH) can also cause a rise in PSA level. Urinary tract infections, prostate surgery, bladder tests, certain medications (such as NSAIDs, statins, and diuretics), and recent ejaculation can also affect PSA test results. The difficulty in distinguishing prostate cancer from these benign conditions can contribute to false positive results, which can lead men to have unnecessary biopsies (the removal of prostate tissue to test for cancer). Some evidence has shown that only 25 percent of men who have undergone a prostate biopsy because of a high PSA level actually have prostate cancer.
Even when a PSA test correctly identifies prostate cancer, it?s hard to know whether that cancer will be life-threatening. Many prostate cancers are slow growing and don?t need treatment. A high PSA level may result in men being treated for cancers they don?t have or that wouldn?t have spread, exposing them to treatment side effects and unnecessary anxiety.
Doctors have also had difficulty agreeing on what constitutes a ?normal? PSA level. In the past, a PSA of 4 nanograms per milliliter of blood (ng/ml) was considered normal. However, more recent students have shown that some men with PSAs below 4 have prostate cancer, while some men with PSA levels over 4 do not have cancer.
As a result, many medical organizations have pulled back on their recommendation that men get routine PSA screening. Most groups agree that screening should be individualized based on a man?s age, risk factors, and overall health.