PSA Prostate Cancer Screening Not Associated with Decrease Risk of Dying from Cancer
Prostate-specific antigen (PSA) is a protein normally 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 include yearly PSA screening for men age 50 years and 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 to screen for prostate cancer since there are multiple factors that can increase PSA levels. A positive screening test may subject men to unnecessary biopsies to look for cancer. As with any screening tests research is done to try to prove that the screen test is not only capable of detecting the disease but that this earlier detection can improve the quality of life for the patient.
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.
About the study
The study was a systematic review of six previous trials comparing prostate screening with PSA to no screening. There were a total of 387,286 men included in the trial review. Using statistical methods to combine data, the trial found that men that had PSA screening:
- were 1.46 times more likely to be diagnosed with prostate
- had similar rates of death from prostate cancer compared to men who were not screened (analysis of 5 trials)
- had similar rates of death from any cause compared to men who were not screened (analysis of 4 trials)
Certain problems with individual trials were noted. There was unclear blinding of outcome assessors in three trials. In five trials it was not clear how it was decided who would get screening or not.
How does this affect you?
Systematic reviews can provide more reliable results because they have the ability to draw in large numbers of participants and repeated results. However, they must be based on reliable studies. As stated above, the individual studies did have some technical issues that could impact the reliability of these results. The higher level of prostate cancer diagnosis in the screening group most likely indicates that prostate cancer was found in early stages before causing symptoms like 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 life. Later diagnosis made when symptoms arrive may not have impacted death rates from the cancer or men may have died from other causes before cancer became a problem.
With any screening test it is important to acknowledge the benefits and risks. For older men it has a unique twist in understanding 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. Early diagnosis in this case may add unnecessary medical and surgical procedures that decrease quality of life without changing mortality. However, prostate cancer in younger men tends to be more aggressive types of cancer and early diagnosis can make a significant difference. Talk to your doctor about your risk factors for prostate cancer and screening options. Learn the symptoms of prostate cancer and stay vigilant on your overall health. If you feel you have symptoms see your doctor to discuss screening options.
American Cancer Society
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 Sep 14;341:c4543