Prostate-specific antigen (PSA) is produced by the prostate gland. Elevated blood levels of PSA may indicate a problem in the prostate, such as prostate cancer or an enlarged prostate. Current recommendations state that male patients should make an informed decision about PSA screening if they are age 50 years or older, or earlier for those at high risk for cancer. There is some debate in the medical community about the effectiveness or wisdom of using this test as a cancer screening test, because there are multiple factors that can increase PSA levels. Patients may be subjected to unnecessary biopsies because of high PSA levels. As with any screening test, research is being done to try to prove that the test is capable of detecting the disease and that this earlier detection can improve the quality of life and decrease risk of death.
Researchers from University of Florida examined the benefits and harms of prostate cancer screening by reviewing and combining several past studies. The study, published in British Medical Journal, found that screening for prostate cancer with PSA may not reduce mortality rates.
The study was a systematic review of six previous trials comparing screening with a PSA level, with or without a digital rectal exam, to no screening. There were a total of 387,286 men included in the review. Using statistical methods to combine data, the review found that:
Certain problems with individual trials were noted. There was unclear blinding of outcome assessors in three trials. In many of the trials, it was not clear how it was decided who would get screening or not. These factors could influence the outcomes of the individual trials and therefore affect the outcome of this larger review trial.
Systematic reviews can provide more reliable results, because they have the ability to draw in large numbers of participants. However, they must be based on reliable studies. The authors are calling for more research into the reliability and usefulness of PSA screening. The higher level of prostate cancer diagnosis in the screening groups may indicate that prostate cancer was found in early stages before causing symptoms or becoming a palpable mass. However, since mortality rates were not different between the groups, it also means that this early diagnosis did not significantly impact the men's lives. Men who did not have screening may have had prostate cancer but died from other causes, or they may have had prostate cancer that was not interfering with their overall health.
With any screening test, it is important to acknowledge the benefits and risks. For older men, it adds a unique twist to understand that prostate cancer is often a slow growing cancer, and although men may have cancer, they may die of other causes before the prostate cancer become symptomatic. In this case, early diagnosis may add unnecessary medical and surgical procedures that decrease quality of life without changing mortality. Talk to your doctor about your risk factors for prostate cancer. Having a discussion with your doctor about the risks and benefits of screening for you is the best way to decide if you should get screened for prostate cancer.
Prostate Cancer Foundation
National Cancer Institute
Djulbegovic M, Beyth R, Neuberger M, et al. Screening for prostate cancer: systematic review and meta-analysis of randomised controlled trials.BMJ. 2010 September 14;341:c4543.
Last reviewed October 2010 by Brian P. Randall, MD