Cancer screening is the process of routinely checking for cancer
when there are no symptoms. Screening for prostate cancer consists
of the digital rectal exam and the prostate-specific antigen (PSA)
test. In a digital rectal exam, a doctor inserts a gloved finger
into the rectum to feel for lumps or abnormalities in the prostate
gland through the rectal wall. The PSA test is a simple blood test
that determines the level of PSA - a protein excreted by the
prostate gland - in the bloodstream.
The medical community is deeply split on the benefit of the PSA
test. Even though the PSA test is often billed as a simple blood
test that can detect cancer early and save men's lives, there
is little unquestionable evidence that the PSA test really does
save lives. Opponents of the test further argue that without a
clear-cut benefit, screening isn't worth the risk because
treatment carries a risk of serious side effects, such as impotence
and incontinence.
What do the various medical organizations currently recommend
regarding the PSA screening test?
The American Cancer
Society and the American Urological Association currently recommend
that health care providers:
- Offer PSA testing and digital rectal exams every year to
all men beginning after age 50.
- Begin testing men at the age of 45 if they are at high risk,
such as African Americans and men who have a first-degree relative
(father, brother, or son) diagnosed with prostate cancer at an
early age (younger than age 65).
Most U.S. government agencies--the National Cancer
Institute, the Centers for Disease Control and Prevention, and the
U.S. Preventive Services Task Force--do not recommend
widespread screening though they agree it should be offered to
those who want it.
The American Medical Association recommends simply that doctors
inform their patients about the pros and cons of screening and
leave the decision to them.
With medical organizations in disagreement about PSA
screening, what should all men know about the current state of PSA
testing and what issues should they discuss with their doctor?
- Researchers are currently questioning the threshold level of a
"PSA less than 4.0" as the "normal" value below which a biopsy
isn't needed. While the screening test does pick up prostate
cancer before it spreads, it also misses many aggressive cancers
that occur at PSA levels well below 4.0 ng/ml.
- The PSA screen is imprecise because both benign and malignant
tissue can cause elevations of PSA in the blood. In addition,
certain medical conditions, such as prostatitis, urinary tract
infections, and prostate enlargement, can also elevate PSA levels.
On the other hand, certain drugs can interfere with PSA testing and
lower reported PSA levels.
- How fast a PSA level rises over time is gaining attention as
possibly more important than whether or not a PSA level is above or
below 4.0 ng/ml. Studies to determine the degree of increased
cancer risk and at what level to recommend biopsy are ongoing.
- Although a screening test may detect cancer, most cancers are
slow growing and may never threaten the life of patients. Older
patients may very well end up dying of another cause before the
cancer caused any symptoms. Men in their 40s, on the other hand,
who have long lives ahead of them, and during which the cancer
could grow and cause them to die, may opt for regular PSA
screening.
- Recent research has found that the higher a man's PSA
level is when he is younger, the more likely he is to develop
prostate cancer later in life.
- Finally, also keep in mind that newer research has found that
PSA screening does pick up some dangerous cancers early.