A prostate-specific antigen (PSA) test reveals how much of a particular protein produced by the prostate gland is circulating in the blood. A high level of this protein circulating in the blood may be caused by a benign or cancerous prostate condition. Although there is some controversy as to when and how often a man should have his blood tested for PSA levels, the common recommendation is a yearly test beginning at age 45 to 50, depending on family medical history and other risk factors.
Significance
While some experts say that PSA testing is misleading and useless in terms of predicting prostate cancer outcome, a study by the Cancer Institute of New Jersey (CINJ) published in the September 2009 issue of the Journal of the American Medical Association found that that survival rates from prostate cancer have improved since the early 1990s, specifically because more PSA testing is being done, resulting in more earlier diagnoses.
Levels
A normal PSA blood level in a healthy man is under 4 nanograms per milliliter (ng/mL). Generally, if PSA levels are between 4 and 10, a man's chance of having prostate cancer is about 25 percent, or 1 in 4, according to the American Cancer Society. A PSA over 10 means a 50 percent, or 1 in 2, chance of cancer. Some men with lower PSAs may have prostate cancer, howeve, and some with higher PSAs may not.
Risk Factors
Age, race and family history are all established risk factors for rising PSA. As men age, PSA levels generally rise even if there are no changes in the prostate. African-American men appear to be at higher risk of developing prostate cancer than Caucasian men. The reason for this is unclear, however, and may have more to do with late detection than ethnic differences. Any man with a family history of prostate cancer is at higher risk than a man with no medical history.
Benign Causes
PSA levels can rise for many reasons, including benign prostatic hyperplasia, or enlarged prostate. Many men develop this condition as they get older. Prostatitis, or an inflammation of the prostate gland due to infection, will cause PSA blood levels to go up. Ejaculation can also cause PSA to rise temporarily, so sexual activity within several hours of having a PSA test is discouraged.
Considerations
After a prostate cancer diagnosis, PSA levels are used to monitor the cancer and decide whether to start treatment and which treatment to use. A high PSA level at this point may indicate that the cancer has spread or that a chosen treatment is not working. The best indicator of the presence or recurrence of cancer is not the actual number but the speed at which PSA levels rise. This is known as doubling time, or the time it takes for the PSA number to double.
