Sunday, October 9, 2011

Study of the Week

And controversy of the week.

This past week the US Preventative Services Task Force (USPSTF) release its latest recommendations regarding the PSA test.  The PSA (prostate-specific antigen) is an enzyme produced by the prostate.  It can be elevated in men with prostate cancer.  Many other things can elevate it- including infections, benign prostatic hypertrophy (the prostate getting larger as someone gets older) and certain drugs.  It is a test with very poor specificity, meaning that there are a high number of false positives.  Most people who have an elevated PSA do not have cancer.

Prostate cancer is most commonly a very slow growing cancer. It is very common- many older men will get prostate cancer and never have a problem with it- they will die with it, but not from it.  However, a subset of prostate cancers are very aggressive and metastasize quickly.  The problem is that it can be very difficult to tell which cancers are slow growing and which are aggressive.  Therefore, most men with a diagnosis of prostate cancer get some sort of therapy- they either have their prostate removed or have radiations.  The potential side effects are severe and very common- impotence and urinary incontinence.  Some men who are older at the time of their diagnosis and have a very small focus of cancer do chose "watchful waiting," and don't do any definitive treatment.

The USPSTF reviewed several high-quality studies and found that screening for PSA does not reduce the death rate from prostate cancer.  What it does seem to lead to is more interventions.  More prostate biopsies, which are quite painful.  More surgeries and more radiations.

So, what's the problem?  Why order (or request) the test at all?  Because everyone knows someone whose prostate cancer was found by an elevated PSA, received treatment, and is now fine.  It's really hard to look at that person and say "Well, you probably would have been fine anyway."  There is also the very real chance that that man was saved by the PSA test.  The USPSTF makes its recommendations for the population, not individuals.


So, should you have a PSA test?  I can't answer that, because the answer is different for everyone.  You need to talk to your doctor about it.  This is just another example of how medicine is as much an art as a science.

1 comment:

  1. Oh what really gets me is when the dr, recommends something like colonopy and find precancerous cells and want said patient to get another one in a year but some people only cover it every two? Why is that?

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