The PSA Dilemma

Since the widespread use of PSA testing in the early 1990’s, there has been a dramatic evolution in prostate cancer detection. With routine PSA screening, prostate cancer is being found earlier and studies show men with the disease are living longer. In fact, there has been a documented 44% decrease in prostate cancer mortality in the PSA era.

Despite this information, the U.S. Preventative Services Task Force recently recommended against routine PSA screening. They concluded that the “benefits of PSA-based screening for prostate cancer do not outweigh the harms” and the “harms associated with the diagnosis and treatment of screen-detected cancer are common…”

This unfortunate conclusion was based primarily on the results of a U.S.-based study called the PLCO (Prostate, Lung, Colorectal, Ovarian) Cancer Screening Trial. This study evaluated 77,000 men who were randomized to PSA screening vs. a control group with no screening. The study found no difference in prostate cancer mortality in the two groups. The major flaw with this study was what is referred to as “contamination.” Up to 40% of the men in the study had actually already undergone PSA screening prior to enrolling in the study. In the control (no screening) group, over 75% of men ultimately underwent screening anyway. Thus, the PLCO study has significant contamination and is really not a fair trial between screening and no screening.

What is believed to be a better metric of PSA screening is the European Randomized Study of Screening for Prostate Cancer (ERSPC). This trial included over 180,000 men from 8 different European countries, again randomized to PSA screening vs. no screening. This trial found a 27% reduction in prostate cancer mortality with 13-year follow up. The findings were most compelling in Sweden, where almost none of the men had ever been given a PSA test prior to the study, so they were a truly unscreened population. In that country, there was actually a 38% reduction in prostate cancer mortality. The study also found that the benefit of screening was most significant in men aged 55-69.

Based on this study, the American Urologic Association (AUA) responded to the U.S. Preventative Services Task Force:

“The AUA strongly believes that the USPSTF, in disparaging the PSA test before a newer diagnostic tool is more readily available, does a great disservice to American men and may cause more harm than good.” The AUA has also subsequently published its own guidelines regarding PSA screening:

• Under age 40 – AUA recommends against routine PSA screening (no data to support it)
• Age 40 and 54 – AUA recommends routine PSA screening only for men at high risk (strong family history or African American)
• Age 55 to 69 – AUA recommends “shared decision-making between men and their doctors“ about routine screening, including discussing the benefits of screening as well as the risks of over-diagnosis
• Age 69 and over – no benefit to routine PSA screening

The main drawback of PSA screening is the increased risk of over-diagnosis and subsequent over-treatment of clinically insignificant prostate cancer (cancer that does not cause symptoms or lead to death).

PSA screening has its limitations, but enables early detection of clinically significant prostate cancer and should not be abandoned. With PSA screening and more precise prostate cancer detection, we can better discriminate men who need aggressive treatment from those who do not.