Prostate screening standards criticized
Narrow guidelines miss many tumors, key physician says
By Peter Gorner, Tribune science reporter. Tribune news services contributed to this report
Reprinted courtesy of: Chicago Tribune
July 24, 2003
The physician who showed that a blood test can be used to screen for prostate cancer says the current guidelines for the commonly used tests may be missing as many as 82 percent of the cancers in younger men and 65 percent of those in older men.
In a study published Wednesday in the New England Journal of Medicine, Dr. William Catalona, director of the clinical prostate cancer program at Northwestern Memorial Hospital, urged that the current cutoff being used for recommending biopsies be lowered in order to save more lives.
The suggestion, he acknowledged, is controversial and will add to the debate over how best to test for the disease and treat it. Critics argue that lowering the test threshold would lead to more biopsies, cost more money and put many men through frightening, uncomfortable and often unnecessary procedures.
Although prostate cancer is the second most common cancer in men, after skin cancer, it may not cause problems. Experts say many older men are walking around with cancerous cells in their prostates that will never become dangerous.
Nonetheless, prostate cancer creates a big health burden. The disease will be diagnosed in nearly 221,000 men--and kill 29,000 of them--in the U.S. this year. And treatment brings its own risks, including impotence and urinary incontinence.
The test, which screens for a circulating protein called prostate specific antigen, or PSA, has been in widespread use since Catalona published a landmark study in the New England Journal of Medicine in April 1991. Most urologists believe that annual screening that includes PSA testing greatly reduces prostate cancer deaths.
In addition, mortality estimates show a significant drop in death rates for prostate cancer patients (20 percent among white men and 11 percent among African-Americans) in the last few years, indicating that advances in screening and treatment are making an impact.
In the new study, co-written by Catalona and colleagues from the Harvard School of Public Health, the researchers evaluated 6,691 volunteers at the Washington University School of Medicine in St. Louis.
They found that men under age 60 with prostate cancer showed a "healthy" PSA reading 82 percent of the time. For older men, it was 65 percent.
"The traditional PSA cutoff--a value of 4 [nanograms per milliliter of blood]--is too high. It misses too many prostate cancers," Catalona said. "If we used a lower cutoff --I've been using 2.5 since 1995--it would allow us to detect the prostate cancers earlier and probably have a better outcome of treatment."
Lowering the cutoff for men under 60 would double the tumor detection rate to 36 percent, while the ratio of healthy men who would be subjected to unnecessary biopsies would rise from 2 percent to 6 percent, the researchers said.
Some experts were respectful but skeptical.
"It seems obvious that if you biopsy more people, you'll diagnose more cancer," said Dr. Mitchell Sokoloff, a urologist at the University of Chicago Medical Center. "But are we actually diagnosing cancer that's important? By lowering the cutoff, are we really curing more men? To me that remains unproven."
In an accompanying editorial, two doctors from the Erasmus Medical Center in Rotterdam, Netherlands, cautioned that "this recommendation is not ready for routine clinical practice."
They said there was no conclusive evidence showing that PSA screening actually reduces the risk of death from prostate cancer without unacceptably reducing a man's quality of life.
Early work by Catalona at Washington University found that testing for elevated levels of PSA can indicate prostate cancer. However, levels also rise due to other factors, such as the non-cancerous condition called benign prostatic hyperplasia, or recent surgeries or infections.
Catalona notes that testing for PSA remains controversial.
"It has not yet been proven to the satisfaction of skeptics that early detection will lower the death and suffering rate from prostate cancer," he said. "But many clinical studies indicate that PSA screening largely detects tumors that are likely to impact the patient."
Copyright © 2003, Chicago Tribune