Saturday, June 16, 2012

PSA Testing: Yea or Nay?

In the town I live in, we have an annual "Fathers' Day Prostate Cancer Walk". This year will be the 14th annual, and the disease is continuing to increase in numbers, despite ongoing research and funding. We often see advertisements to "get checked", but recently, medical studies have questioned whether PSA testing is helpful.(NEJM, March 2012). This study concluded, that although PSA screening decreased the mortality from Prostate Cancer by 21%, it did NOT reduce the overall mortality rate. In fact, to prevent ONE death from prostate cancer, you would need to screen over 900 men.

So, is this a good screening tool?

What is a Good Screening Tool?

We tend to like answers to questions to be black or white. For example, I want the answer to my prostate test to be "No, you do NOT have cancer."
I don't want to hear, "Well, you probably don't, but I'm not 100% sure." Unfortunately, NO screening test can give you a one-hundred percent guarantee.
Screening tests should do the following, in the best cases.

  • It tests for an important disease
  • There is treatment available, when given early has more benefit than if giving later in disease
  • The prevalence of the disease is relatively high
  • The test is relatively inexpensive
  • The test is consistent
  • The test is VALID (ie. can distinguish between real disease and normal state)
  • The test is easy to administer and causes little discomfort
Looking at these features, a test like measuring Blood Pressure is a good screening tool. It's easy to do, and if you treat it early, you can prevent a lot of complications.

Doing a PSA Test is a little more tricky. 

Why the Controversy?

The controversy as to whether PSA testing is a good screen is for a few reasons. Unfortunately, the lab result is NOT an absolute answer. It doesn't give that clean black/white answer we crave. You simply get back a number, and are left to interpret what it might mean. Obviously, a sky high value is worrisome for cancer, but, where should the cut-off be? We can't have it be too high, or we'll miss some cases, but if we set the cut-off too low, we start biopsying patients who don't have cancer. This causes undo stress and anxiety in patients, for no good reasons.

The other problem (although a better problem to have) is that prostate cancer tends to be a slow growing cancer. In other words, it's not uncommon that if a man was never screened, he likely would die of some other cause than the prostate cancer itself. In other other words, NOT ever knowing might have been fine.

Finally, the treatment, be it surgery, radiation, or other, is NOT without it's own complications. Infections, incontinence, impotence are possible, for a disease which might not have killed you in the first place.

All that being said, I have also seen many cases of prostate cancer with awful endings, as well.

So What Should I Tell My DAD to do?

I think the best advice, is for every man over 40, to at a minimum see their physician for an annual check up. As a family doctor, I don't see nearly enough middle aged men on any regular basis. A discussion about the pros and cons of the nowhere near perfect PSA test should take place, and irregardless, a digital rectal exam should be done. 
If after discussion, knowing the risk/benefit of the PSA lab test, I offer it to all my middle-aged men.

Definitely a complicated topic with no right answer in my opinion.
Let me know what you think, and don't forget to wish your dad a HAPPY FATHER'S DAY!

No comments:

Post a Comment