To PSA or Not to PSA

Posted by Mark Abramowicz, M.D.

That is the question the US Preventive Services Task Force (PSTF) and Warren Buffett have answered in opposite ways. The USPSTF has recommended since 2008 against screening for prostate cancer with a PSA test in men more than 75 years old, and since 2011 has expanded that recommendation to include younger men as well. Warren Buffett, who is more than 80 years old, recently had prostate cancer detected by a PSA test and will undergo radiation treatment. Which one is right?

The argument against PSA testing is that it has not been shown to save lives, and can lead to unnecessary and harmful treatments. The PSTF concluded that there is a “moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits.” The 2 large controlled trials (New England Journal of Medicine, Oct. 26, 2011), one in the US and one in Europe, that led to the most recent PSTF recommendation were both limited by “contamination”: many patients who were supposed to be screened were not screened, and many of those who were not supposed to get PSAs in fact did get them. The study in the US had a roughly 50% contamination rate in both directions, so it should hardly be surprising that there was no difference in prostate cancer mortality between the 2 groups. The European study had a lower (about 20%) rate of contamination, but after 11 years of follow-up that study found a 21% lower prostate cancer mortality rate among the men assigned to screening.

One argument for PSA testing is that US death rates from prostate cancer have fallen by about 4% per year since 1992, 5 years after PSA testing first started. Another, not very scientific, is that 95% of male urologists reported in a survey that they have had PSA tests themselves. Urologists know better than anyone about the side effects and complications of prostatectomies and radiation, but apparently they are willing to risk those, perhaps unnecessarily, to avoid the greater unpleasantness of advanced prostate cancer, with its painful metastases to bone.

And what about Warren Buffett and the other men over 75? The PSTF says they have no business getting tested because their life expectancy is too short: a prostate cancer detected by a PSA test would probably not become symptomatic in the man’s lifetime, or at least would not kill him before he died of something else. About 70% of prostate cancer deaths occur in men more than 75 years old. From 2005-2009, according to the National Cancer Institute, the median age at death for cancer of the prostate was 80 years of age. Some of those men, like the urologists, would probably prefer to take their chances with impotence or incontinence over dying of prostate cancer. There is no proof that PSA testing will save lives in this age group, and probably there never will be, given the difficulty of conducting the necessary studies. So we all have to rely on our common sense. Like Warren Buffett.

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