Prostate Cancer Screening Questioned
Government Panel Says Benefits Uncertain
Dec. 3, 2002 -- Men looking for a simple answer to their
questions about prostate cancer screening will find little solace in the
findings of a major government task force. After reviewing recent research on
the issue, the group says there is not enough evidence to make a recommendation
for or against routine prostate cancer screening.
Prostate cancer is the most common cancer among men and the
second leading cause of cancer death among men, following lung cancer.
According to the American Cancer Society (ACS), 189,000 men will be diagnosed
with prostate cancer in the U.S. this year, and more than 30,000 men will die
of the disease.
Death rates from prostate cancer have dropped since the use of
prostate cancer screening tests, such as the PSA blood test and rectal exam,
became common in the 1990s, according to the ACS. However, there is no direct
evidence that this drop is a result of screening tests.
The results of the U.S. Preventive Services Task Force report
appear in the Dec. 3 issue of the Annals of Internal Medicine.
Researchers say one of the biggest problems in evaluating the
effectiveness of prostate cancer screening is that the severity of the tumors
varies greatly, and the screening tests aren't very specific.
Many of these tumors grow very slowly and may not ever cause a
problem for many of the men diagnosed with the disease. But current screening
methods can only distinguish a small number of men with either the best or
worst chances for survival. They aren't very good at making predictions about
the survival chances for men who fall in the middle, which accounts for the
vast majority of prostate cancer cases.
Although there are virtually no health risks associated with
the screening tests themselves, experts say the risks associated with
widespread prostate cancer screening lie in the uncertainties about the disease
itself, how to interpret test results, and making treatment decisions.
Durado Brooks, MD, MPH, director of prostate cancer at ACS,
says men need to understand that the PSA test, which measures the level of a
protein produced by normal prostate cells as well as prostate cancer cells,
still misses about 10% to 15% of cancers.
Even if PSA levels are found to be higher than normal, Brooks
says it is very often due to something other than cancer, such as benign
prostate enlargement. Even so, he says those results may still cause
unnecessary anxiety for many men.
"Once you do a prostate cancer screening, decisions have to
be made about treatments that can have some very untoward side effects,"
He says a significant percentage of men who undergo prostate
cancer treatment suffer from urinary and bowl incontinence as well as erectile