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Official Guidelines for PC screening
with PSA and DRE from the U S Preventive Services Task Force. (January
2003)
In the December 3 issue of the ANNALS OF
INTERNAL MEDICINE the US Preventive Services Task Force updated its
recommended guidelines for screening for prostate cancer. This task force
is a unit within the Agency for Healthcare Research, a subdivision of the
Federal Department of Human and Health Services. The task force is an
independent panel comprised of experts in family practice and other
subspecialties and heath care professionals. The chairman is Dr. Alfred
Berg, MD,MDH, University of Washington. Their analysis is based
essentially on an extensive literature review with a careful weighing of
the strength of the various pieces of evidence. And, of course, the view
is retrospective. Their conclusions:
1. The USPSTF concludes that there is insufficient evidence to recommend
for or against routine screening for prostate cancer using PSA testing or
digital rectal examination.
2. The USPSTF found good evidence that PSA screening can detect
early-stage prostate cancer, but mixed and inclusive evidence that early
detection improves health outcome.
These recommendations are endorsed by the American Academy of Family
Practice, the American Cancer Society, the American College of
Physicians-American Society of Internal Medicine, the American Medical
Association, and the American Urological Association. None of these
organizations endorse mass screening for any group of men. Most medical
organizations, however, do recommend that physicians discuss with their
patients the potential benefits and harms of PSA screening. It is
generally acknowledged that the men most likely to benefit are 50 years or
older (younger than 50 years if an increased risk for PC exists), and men
with life expectancy of fewer than 10 years are less likely to benefit. In
the same issue Drs. Harris and Lohr retrace the same literature in a broad
review covering screening and efficacy of various treatments. They also
conclude that "The benefits of screening for early prostate cancer remain
"unknown" [italics mine].
Unknown is the key word in this whole topic. A literature review is by its
very nature retrospective. Only two randomized controlled trials (RCT)
have been reported. One was by Labrie in PROSTATE 1999 wherein no
advantage was found for screening. The only other RCT was reported in the
New England Journal of Medicine, September 2002, (reviewed in the
September PCa Commentary) which found a reduction in prostate cancer
specific deaths favoring prostatectomy versus "watchful waiting" with
later treatment if indicated. There are two large scale RCTs in progress
addressing screening for early PC comparing immediate treatment versus
observation (and possibly subsequent treatment), but the results will be
several years in coming, and there is no assurance that their results will
settle this issue. We can hope that advances in science will get us past
this thorny issue. The essence of the dilemma is that PC is a
heterogeneous disease presenting a spectrum of degrees of aggressiveness.
Some cancers, however small, may be unmanageably aggressive from their
inception, some aggressive but manageable, some with intermediate
characteristics which permit cure if treated early, and some indolent and
undeserving of intervention. We need to be able to discriminate among
these and offer appropriate guidance. There is considerable hope that this
discrimination can be achieved by evaluating prostate biopsy material with
gene expression analysis employing DNA microarray technology. An article
in the December 19 issue of the New England Journal of Medicine reported
that by micro array analysis it was possible to separate aggressive breast
cancer from more indolent disease. Certainly that same type of information
can be achieved for prostate cancer. [DNA microarray technology and some
early findings relevant to PC will be discussed in the February issue of
PCa commentary]
Bottom Line: The benefits of PSA screening are unknown, but modern science
may come to the rescue.
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