PSA (Prostate-Specific Antigen) is a simple blood test that serves as an important marker of the prostate and prostate cancer. It's discovery in the 1980s has been the major reason that generally speaking prostate cancer is caught much earlier than in previous years. In fact, it's also the major reason that patients with newly diagnosed prostate cancer typically have no symptoms (other than an elevated PSA). Prior to the discovery of PSAs, prostate cancer was detected only at more advance stages - when the patient had symptoms or the cancer could be felt on digital rectal examination (DRE). The mortality (death) rates from prostate cancer in the current decade is lower than that in the last decade largely because of the increased use and awareness of PSA.
When should PSA testing begin?Both the American Urological Association and the National Comprehensive Cancer Network (NCCN) are now recommending prostate cancer screening and PSA testing begin at age 40.
Many patients ask "What is a normal PSA result? When should I be concerned?"
More recently, it has been suggested that 2.5 ng/mL and above be considered "abnormal." The American Urological Association has recently noted that there is no PSA level at which the risk of prostate cancer is zero. Multiple things need to be considered before going to the next step (a prostate biopsy), including PSA value, PSA velocity, results of the digital rectal exam (DRE), family history, etc. Your urologist should discuss your PSA results with you individually.
In March 2009, 2 studies were published in the New England Journal of Medicine regarding PSA. You may have heard about these studies in the news. The smaller of the two studies, involving about 70, 000 suggested no survival benefit to prostate cancer screening at 7 years. Unfortunately, critical review of this trial has uncovered many flaws. To begin with, 7 years is not an adequate length of time to show a survival benefit to screening since the goal of treatment for this disease is to prevent prostate cancer related morbidity and mortality beyond 10-12 years. Secondly, the patients were not in 2 clear groups. That is, to design a trial evaluating PSA screening, one must have two groups of patients - a screened group, and an unscreened group. Unfortunately, many patients in the "unscreened" group did actually have PSA testing done which may have selected out many cancers from this group. Such "contamination" of the control group is a major flaw of this study. Lastly, a single "cut point" for abnormal PSA was used and we now know that there is really no PSA value below which there is no risk of cancer.
However, the other study published, of a much larger 162,000 men, found a 20% reduction in death in the group that underwent PSA screening. As expected, it took more than 10 years to show such a difference. However, if you consider patients that underwent prostate biopsy, the reduction in mortality with PSA testing is EVEN GREATER - about 27%. A recent update on this study, published by Roobol et. al. in European Urology, suggested when some of the flaw of this study were adjusted for, PSA screening was associated with up to a 33% reduction in prostate cancer death at 9 years.
The large European trial does provide evidence that PSA testing IS saving lives. The benefit of PSA testing will probably be most to health men less than 70 years of age, who are predicted to live more than 10 years. However, there is controversy regarding PSA testing, and it is important that men be aware of this before getting a PSA test and when interpreting the results.