Feb. 18, 2000 (Baltimore) -- A statistical drop in the rate of deaths from prostate cancer since the early 1990s has been influenced by the widespread use of a screening test called PSA, reports a study published in the February issue of the Journal of Urology.
The test, which was approved by the FDA in 1986, had led to an increase in the reported rate of prostate cancer deaths in the late '80s and early '90s as more cases were detected, the authors say.
"Most of the decline in mortality due to prostate cancer we're seeing currently is due to reductions in the number of men with distant disease [cancer that has spread beyond the prostate gland]," Robert Stephenson, MD, one of the study's co-authors, tells WebMD. Stephenson is a professor of surgery at the University of Utah College of Medicine. "We're diagnosing [it] at earlier stages, and this seems to be having an effect on mortality."
In the U.S., prostate cancer is the most common cancer in men 50 and older. More than 200,000 new cases are reported each year. Because prostate cancer develops slowly, many men initially experience no symptoms. PSA, which stands for prostate specific antigen, is an important test because an elevated PSA level may be the first and only indicator of this disease.
PSA, a blood test, is routinely performed on men 50 and older during yearly physical exams. Black men may be screened starting at age 40 due to the higher incidence of the disease and earlier onset in this group.
Stephenson and a colleague, Ray Merrill of Brigham Young University, examined data on prostate cancer incidence and mortality from a large database administered by the National Cancer Institute, called the SEER Program. The program has been collecting cancer data since 1973.
Statistical analysis reveals that the reported prostate cancer mortality rates increased from 1988 through 1992, then decreased. "What happened is that with the widespread use of PSA in the late 1980s, we detected many more cases of prostate cancer than we had before," Stephenson says. "In 1992, detection peaked, and now we're back to levels similar to what we saw before PSA."
A researcher who was not involved in the study tells WebMD that the statistics do not prove PSA screening was responsible for the drop.
"There have been numerous studies trying to explain this phenomenon," says Janet Stanford, PhD, head of the prostate cancer research program at the Fred Hutchinson Cancer Center in Seattle. "We won't really know the answer to this question for several years, when data from randomized trials of PSA screening and its impact are made available."
Until then, Stanford recommends that men follow American Cancer Society guidelines. "The guidelines provide that after age 50, men should annually have both PSA testing and a digital rectal examination. If they have a family history of prostate cancer, they should begin earlier," says Stanford.
What this means for most men with prostate cancer is that the disease will be diagnosed at an earlier stage, and treatment will likely involve just the prostate gland itself, Stephenson says.