This
article, published on 28 May 2003, describes a study at Sloan Kettering Memorial
Hospital which reinforces the view that a single elevated PSA test result should
not be used as the basis of a biopsy, since many PSA numbers will revert to normal
levels without treatment.
NEW YORK, May 28, 2003 -- A PSA (prostate specific antigen) blood test is part
of routine prostate cancer screening for most men over 50. If the test result
shows a moderately elevated PSA level, a referral for a biopsy is usually recommended.
There is now evidence that suggests biopsy should not be performed until the test
is repeated because PSA levels commonly fluctuate above and below the normal range.
In a study published in the May 28 Journal of the American Medical Association,
researchers from Memorial Sloan-Kettering Cancer Center and colleagues studied
nearly one thousand men who had five consecutive PSA tests over a four-year period.
Up to one third of these men had elevated PSA levels; a finding which usually
results in a referral for a prostate biopsy. However, subsequent testing of the
same men a year or more later indicated that the PSA levels for half of the men
had returned to normal. Had a biopsy been performed, it may have been unnecessary.
"A single, elevated PSA level does not automatically warrant a prostate biopsy,"
said Dr. James Eastham, a surgeon in the Department of Urology at Memorial Sloan-Kettering
and the study's lead author. "We recommend having the findings confirmed by repeating
the PSA test after waiting at least six weeks. Even if the repeat test shows an
elevated level, prostate cancer will only be discovered in about one quarter of
men who undergo biopsy."
The retrospective study looked at a population
of 972 men with a median age of 62 years who participated in a national colon
polyp prevention trial. These men were considered typical of the healthy male
population at risk for developing prostate cancer, a disease that will be diagnosed
in approximately 220,900 men this year. Annual blood samples were stored and later
analyzed in order to study natural variations in PSA levels (serum prostate specific
antigens circulating in the blood), a measurement frequently used in early detection
programs for prostate cancer. Men who had five consecutive blood samples available
over a four-year period were included in the study. While 21% had an elevated
PSA (>4.0 ng/ml) at some time during the study, the level subsequently returned
to normal spontaneously in nearly one half of the men and remained normal for
most of them on further tests. A prostate biopsy of these men would not have been
necessary.
"These natural variations in PSA detract from its use as a
screening tool," said Colin Begg, Ph.D., chairman of the Department of Epidemiology
and Biostatistics at Memorial Sloan-Kettering and senior author of the study.
"A policy of confirming newly elevated PSA levels several weeks later may reduce
the number of unnecessary procedures as well as the number of men diagnosed with
a small, incidental tumor that poses no threat to life or health."
Waiting
to confirm the diagnosis will not have an adverse affect on those men who actually
have prostate cancer, according to Peter Scardino, MD, chairman of the Department
of Urology at Memorial Sloan-Kettering. "A delay in diagnosis of a few weeks or
months is unlikely to alter treatment efficacy," said Dr. Scardino.
The
study co-authors include Ellyn Riedel, M.A., Moshe Shike, M.D., Martin Fleisher,
Ph.D., and Liane Litkany of Memorial Sloan-Kettering; Arthur Schatzkin, M.D.,
DrPH and Elaine Lanza, Ph.D. of the National Cancer Institute; and the Polyp Prevention
Trial Study Group. It was funded by grants from the National Cancer Institute
and by CaPCURE, the Association for the Cure of Cancer of the Prostate.
Memorial Sloan-Kettering Cancer Center is the world's oldest and largest institution
devoted to prevention, patient care, research and education in cancer. Our scientists
and clinicians generate innovative approaches to better understand, diagnose and
treat cancer. Our specialists are leaders in biomedical research and in translating
the latest research to advance the standard of cancer care worldwide.
