The PSA Test. Is It Worth It?

Sunday March 22, 2009

The results of two large research studies that sought to evaluate the worth of the PSA test were recently published in the New England Journal of Medicine.

Both studies looked back over a number of years to determine whether men who had undergone PSA and digital rectal exam screening for prostate cancer actually had lower rates of death from prostate cancer than men who hadn't undergone any screening.

One of the studies, which was based in Europe, found that, yes, men who had undergone prostate cancer screening did have lowered rates of death from prostate cancer (up to 20% lower).

However, it was also found that, in order to prevent one death from prostate cancer, approximately 1400 men would have to undergo prostate cancer screening. Furthermore, a certain percentage of men who undergo screening eventually proceed to more invasive testing such as prostate biopsy, which has its own set of risks and complications.

So far, most of the editorials and opinions in the American media have focused on the fact that a large number of men need to be screened and tested for prostate cancer in order to save even one life from prostate cancer. This is true, but the results of these studies really don't change what doctors have been saying all along - that the PSA test is imperfect, but still the best that is available (when used with regular digital rectal exams) for early detection of prostate cancer.

In my opinion, the PSA test should be interpreted with a more nuanced approach. Other indicators such as the PSA velocity, the PSA density, and the percent-free PSA have been shown to be useful for determining which elevated PSA levels are the most likely to represent prostate cancer that is the most dangerous.

Abandoning the PSA test because of its imperfections is unwise and very unlikely to happen until a proven superior test is developed.

Here are links to the two studies that were recently published in the NEJM.

The American trial and the European trial.