The PSA (Prostate-Specific Antigen) test is one of two primary screening tools for prostate cancer. This simple blood test measures the level of PSA, a protein produced in the prostate, present in a man's body. Men typically have an initial PSA screening at 50, or earlier if there's a family history of prostate cancer.

Physicians measure PSA in nanograms per milliliter. An elevated PSA doesn't diagnose cancer and doesn't mean a man has prostate cancer; it just suggests further evaluation. Other medical conditions can also raise PSA levels. A PSA test and additional diagnostic tools help detect small tumors, however, experts say it does not necessarily reduce a man's chance of dying of prostate cancer.

An increase in PSA is the strongest single predictor of prostate cancer risk, and a high PSA score followed by a lower PSA score is not uncommon, even in men who do have cancer. However, PSA progression does predict poor overall survival rates in men with mestacized prostate cancer (meaning it has spread beyond the prostate). The PSA test is actually a better predictor of prostate cancer risk in African-American men with family histories compared to European- American men.

There is controversy over the value of PSA screenings. This spring, researchers released the results of a large-scale study that began in 1992 to evaluate whether or not the PSA test benefited men. In the subsequent media coverage of the results, the news varied widely depending on who was doing the reporting.

In a video to other physicians posted in the April 2009 issue of Family Medicine, Robert Morrow, MD, cut through the media clutter and reported that the men in the study who were screened for prostate cancer died, while those who were not tested lived longer, and better. As he explains, screening does not diagnose cancer, but looks for disease that is not apparent. Physicians fear repercussions if they don't recommend a PSA test and a patient subsequently dies of prostate cancer. Furthermore, since an elevated PSA score alone does not indicate cancer, physicians then need to recommend additional testing (usually a biopsy) to make a diagnosis, followed by treatment if cancer is detected. Skeptics are not sure the benefits in fact outweigh the risks, citing potentially harmful side effects from biopsy and unnecessary treatments.

To date, the PSA test is still the best screening tool for prostate cancer. If your doctor recommends a PSA test, ask him or her to explain all the potential benefits and risks of the test.