Prostate-specific antigen (PSA) is a protein made in the prostate that passes through the semen and into the bloodstream. A high PSA level may indicate the presence of prostate cancer, but it also can be caused by other conditions, such as an enlarged prostate (benign prostatic hyperplasia, or BPH), or a urinary tract infection.
A PSA test can be used to help decide whether a man should have a digital rectal exam or a biopsy of the prostate. The procedure involves having a sample of blood drawn, which is then sent to a lab for testing. A PSA test can be done in a doctor’s office or in a hospital lab. A PSA test takes about a week to get the results.
PSA is produced by both normal cells in the prostate and cancer cells. The levels of the protein increase with age, so it can be difficult to determine a “normal” range. Moreover, PSA can also be elevated due to other factors that do not affect the risk of cancer, such as ejaculating or having a medical procedure that involves the prostate, or by taking medications including dutasteride (Avodart) or finasteride (Propecia).
Some doctors use a PSA test called the PSA velocity, which measures how quickly the PSA level rises. But the American Cancer Society doesn’t recommend this test as a screening tool because research hasn’t shown that PSA velocity is more predictive of prostate cancer than is just a person’s age or the PSA level itself.
If a man’s PSA level is high, his doctor might suggest he have a digital rectal exam and a prostate biopsy. The biopsy is when a doctor removes a small amount of tissue from the prostate to examine it for signs of cancer or other abnormalities. The procedure is uncomfortable and can cause pain, but it is not dangerous.
The decision about whether a man should have a PSA test is based on his individual health and family history, and it must be made between him and his doctor. The National Comprehensive Cancer Network guidelines for early detection of prostate cancer recommend against routine PSA testing for men between 40 and 54, because the harms of unnecessary biopsies and treatment side effects outweigh the benefits of the test. These guidelines are also based on the finding that the majority of men with prostate cancer in the United States have low- or intermediate-risk tumors.
Men over the age of 70 should discuss with their doctor whether they should have a PSA test and how often it should be repeated. The chart below shows age recommendations and PSA levels for men at average risk, and men who have a higher risk should talk with their doctor to make a plan for screening. A PSA level above 3 ng/mL indicates that further evaluation and screening is necessary, but the exact level depends on the individual’s risk assessment.
