CHAPEL HILL - Although medical scientists still debate the effectiveness of prostate cancer screening known as serum prostate-specific antigen testing and even of prostate cancer treatments themselves, the PSA procedure is performed widely to detect the deadly illness earlier.
A new study conducted at the University of North Carolina at Chapel Hill suggests that current PSA screening strategies should be changed.
Former UNC-CH School of Public Health graduate student Kevin S. Ross, now a Johns Hopkins University medical student, found that testing men earlier likely would be more effective than waiting until age 50. To save money without increasing risks, testing should be done at ages 40 and 45 and every two years after age 50 instead of annually, the study showed.
A report on the research appears in the Sept. 20 issue of the Journal of the American Medical Association. Besides Ross, authors are Drs. Harry A. Guess, adjunct professor of epidemiology and biostatistics at UNC-CH; H. Ballentine Carter, professor of urology at Hopkins; and Dr. Jay D. Pearson of Merck Research Laboratories in Blue Bell, Pa., where Guess heads the epidemiology department.
The study involved computer analyses simulating the natural history of prostate cancer using different starting ages, testing intervals and PSA test result levels at which doctors encourage patients to have prostate tissue samples taken and checked for cancer. Computers allow researchers to tap existing information to create large numbers of patients artificially without the expense of massive clinical trials.
"Specifically, compared with no screening, the standard strategy prevents 3.2 deaths per 1,000 men with an additional 10,500 PSA tests and 600 prostate biopsies," the researchers wrote. "The earlier but less frequent strategy prevents 3.3 deaths per 1,000 men with an additional 7,500 PSA tests and 450 prostate biopsies."
New study suggests prostate screening should be done earlier, every two years
In other words, for every 1 million men, 3,200 lives would be saved under current practice when compared with no screening, the research suggests. With the strategy the researchers evaluated, 3,300 lives would be saved while requiring about 25 percent fewer PSA tests and biopsies.
"By doing a screen at age 40 and another one at age 45, you can often pick up people who are at high risk of cancer or who already have it and may need to be treated," Ross said. "Although the prevalence of prostate cancer is lower in 40- through 50-year-old men compared with older men, younger men with PSA-detected prostate cancers are more likely to have curable disease compared with older men whose cancers are detected by the tests."
Currently, PSA levels above 4 nanograms per milliliter trigger recommendations for biopsies, he said. Lowering that level would greatly increase the number of expensive biopsies done without significantly reducing the number of deaths
"This test is not a great predictor, but it's about the best thing we have at the moment," Ross said. "We are not trying to say screening should be done or that it should be done using our strategy. It's more like, if you are going to screen, our work suggests that the way we're doing it now isn't the best way."
Note: Guess can be reached through (919) 966-7415 or (610) 397-2539, hguess@sph.unc.edu .
Journal
JAMA