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.
