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Wednesday, October 03, 2012

A PSA Screening Discussion


What is screening?

A screening test refers to a medical test that is performed on a patient in the absence of any overt symptoms or signs of a disease.   For example, a person at age 50 might get a colonoscopy to screen for colon cancer even though they have no symptoms that may be suggestive of colon cancer, like constipation or blood in the stool. 

What are some common screening tests?

The colonoscopy, the mammogram, the CBC, the Chem 20, the EKG, and the PSA blood yes, among others. 

What is the PSA test?

The PSA test is a blood test that detects levels of a protein in the blood called prostate specific antigen, or PSA.  PSA, the protein, is actually a component of semen that helps sperm function in the semen.  So PSA is an important reproductive protein.

What is a normal PSA?

Traditionally a PSA of 4.0 or less was normal.  We now know that PSA is much more complex than that.  In some men, a PSA of greater than 4 is normal while in others a PSA of less than 4 is not normal.   Therefore a normal PSA can only be determined as part of a constellation of other factors. 

Does prostate cancer cause the PSA to be elevated?

Prostate cancer can cause the PSA to rise, but it is only one of the causes of PSA elevation.  In addition, prostate cancer can be present with a normal PSA and absent in the face of an elevated PSA.  To complicate matters even further, some studies suggest that as much as 10% of prostate cancers do not produce PSA at all, so these men can have a low PSA and still have prostate cancer.

What else can cause the PSA to rise?

Benign prostate enlargement, prostate infections and inflammation, bladder infections, and retention of urine can all cause the PSA to rise.

Can anything make the PSA go down?

Certain medications can make the PSA drop.  Some commonly used prostate medications and even some popular over the counter prostate herbal supplements can make the PSA drop by as much as 50%.  It is very important the let the doctor know you are taking these sorts of things.

Is there any way to determine what caused the PSA value to rise?

The best way to interpret the PSA value, what ever it may be, is by interpreting it within the context of the patient’s medical history, medication history, prior PSA history, physical exam, and urine analysis and culture results.

What is involved in a PSA screening test?

The test itself is simple blood test.  Most offices can have a result back within minutes to a day at most.

So what is the big deal?  Why not just get the test?

It is true that the test itself is easy to do.  But what we do with the result of the test; that is not so easy answer.  A PSA test can start the patient down a medical path that involves at the very least repeat PSA testing and at the very worst potentially unnecessary medical treatments that have their own set of complications and problems. 

What is this “medical path” that you referred to?

An “abnormal” PSA test can trigger a set of events that many patients—on their own hindsight—would rather have not started down in the first place.  Some men actually get severe anxiety from waiting for their quarterly or semi-annually PSA results.  While this may seem trivial, it is actually quite common and problematic for many men. 

An elevated PSA will also cause many a doctor and patent to proceed to a prostate biopsy.  Prostate biopsies can be falsely negative so some men will require multiple prostate biopsies only to have the biopsies remain negative for cancer.   Some men can even get quite sick from the biopsy itself.  While in general prostate biopsies are safe, many would be surprised to learn that as much as 1/1000 men can die as a result of a prostate biopsy, though I think this actual number is far lower than 1/1000.    

Treatment for prostate cancer is very complicated as well.   Deciding who to treat and with which form a therapy is a surprisingly complex endeavor and highly dependent upon both patient and doctor preferences.   In addition, not all patients will even benefit from all treatments.  Since the treatment of the prostate cancer has significant side-effects, we really want to treat only men that will benefit from the treatment.   The problem is that we have difficulty identifying who these men are and who does not require more than active surveillance. 

Finally, and perhaps this is a lessor issue or it is not, but there are insurance issues that can come into play if a PSA is checked.  By insurance, I mean pre-existing illnesses and the ability to purchase insurance products such as future life-insurance, disability insurance etc.  Many people simply don’t think this far down the road, so to speak.  But these issues can become important issues for the patients and their families and I think they should be addressed proactively. 

Isn’t early detection the key to surviving prostate cancer?

In general, I would agree with this, but with regard to prostate cancer, this is not necessarily true.  Perhaps more important than early detection for prostate cancer is the biology of the tumor itself.   Patients with low-grade tumors tend to do well regardless of the treatment method while those with high-grade tumors tend to do poorly despite the aggressiveness of the therapy. 

Does PSA screening result in detection of more prostate cancer?

Since PSA screening first came into common usage in 1989, prostate cancer detection rates have dramatically increased.    Many of these men--the men that have been diagnosed prostate cancer--no doubt would have gone on to die from advanced prostate cancer.  Some studies indicate that prostate cancer specific deaths have dropped by as much as 40% since the PSA test was introduced.  

Is there a downside to detecting prostate cancer?

On the balance I think that early detection of prostate cancer is a good thing, but there are some definite drawbacks as well.  Not all prostate cancer needs to actively treated and not all forms of treatment for prostate cancer are appropriate for all men.  Some forms of prostate cancer treatment have significant side-effects that may even be worse than the initial disease, the prostate cancer.   A study that was presented the 2011 meeting of the American Urological Association reported that for every 20 men that got surgical treatment for prostate cancer, only one man benefited from that treatment.  So in other words, it is possible that we over-treat prostate cancer in a big way.

So what do you recommend?

I do not advocate routine and reflexive PSA blood testing.  What I do recommend is having a discussion just like this one and then deciding along with the patient whether or not to get the test.  I do also believe that PSA screening and early detection of prostate cancer does save lives but it comes with a certain cost, both human and financial.