Screening for Prostate Cancer w/PSA: What's Our Goal?

"In this world, nothing can be said to be certain except death and taxes."  Benjamin Franklin

Check out USA Today.  The prostate specific antigen (PSA) controversy continues.  Before you pummel me with virtual tomatoes, let's agree to something:  no one is immortal.  In other words, we're all going to die eventually.  The problem then is figuring out from what.  It turns out that increased detection & survivability by screening for some disease doesn't demonstrate that screening saving lives.  What's worse, my primary care colleagues and I don't appear to understand this concept as published in this week's Annals of Internal Medicine.  Reuters is fairly blunt in their assessment.  We overvalue irrelevant evidence (screening increases survival) and overlook relevant evidence (screening decreases mortality).  If you subscribe to this journal, you can take the survey/test and see how your understanding compares to ours.

I mention all this as a prologue to a study released today in the New England Journal of Medicine which is an extension of a study published 3 years ago.  Back then, after screening 182,000 European men via PSA, most of whom were 55-69yo, for 9 years, the authors were able to demonstrate a statistically relevant absolute reduction in prostate cancer mortality of 0.71 death per 1,000 men.  In other words, 1,410 men would need to be screened and 48 cases of prostate cancer would need to be treated in order to prevent one death from prostate cancer.  Put more succinctly, there was a high risk of overdiagnosis.

After 2 additional years of study & observation (11 years total), the findings did not change much, if at all.  1,055 men would need to be screened and 37 cases of prostate cancer would need to be treated in order to prevent one death.  More importantly, there was no difference in all-cause mortality.  

Bottom line, while we would need to overdiagnose a lot of men to prevent a single death, we'd still die at the same age from some other condition.  By screening, we haven't delayed the inevitable.  This is the crux of the content that we must cover in our allotted 15 minutes in order to help men decide whether or not to get screened.  This doesn't even begin to take into account your family history, nor the downside to screening (infection from biopsy) and treatment (incontinence, erectile dysfunction & bowel issues).  So think long & hard, think very carefully before you open up Pandora's box.

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