CHICAGO--Proponents of the prostate-specific antigen (PSA) test
have new ammunition to support the view that the controversial
screening method accurately predicts the progression of prostate
cancer and the long-term survival of patients, thus allowing more
appropriate treatment choices.
Among 317 men with localized prostate cancer who have been treated
since 1986, there was a 75% probability of survival for 5 to 10
years when the pretreatment PSA level was less than 10 ng/mL,
reported Carlos A. Perez, MD, at the annual scientific meeting
of the Radiological Society of North America.
"These findings correspond with other reports that suggest
that PSA tests may be the key to determining who should undergo
therapy, such as surgery or radiation therapy," said Dr.
Perez, director, Radiation Oncology Center, and professor of radiology,
Mallinckrodt Institute/Washington University, St. Louis.
Contradicts Toronto Study Results
The findings also contradict a recent, widely reported study conducted
by researchers at the University of Toronto. These investigators
concluded that screening for prostate cancer using the PSA test
could not be justified (JAMA 272:773-780, 1994).
The authors of the study from the University of Tor-onto found
that screening with the PSA test would require a community to
spend between $113,000 and $729,000 to gain only one additional
year of life expectancy from early treatment of prostate cancer.
PSA screening also would reduce the quality of life for many men
because of treatment side effects.
Even in the best scenario, the Canadian scientists stated that,
with PSA screening, life expectancy would increase by only 0.6
days on average for a 50-year-old man and 1.7 days for a 70-year-old
man. When quality-of-life factors were considered, there was a
net loss of 3 to 13 days in life expectancy.