Two eagerly awaited studies of a total of 250,000 men have raised new questions and concerns about the risks and benefits of the prostate-specific antigen test, or PSA. USA TODAY talked to experts about the studies, the test and why it’s controversial. It thought you’d appreciate this information.
Q. What do the new studies find? Does the PSA test save lives or not?
A. Neither study provides clear-cut answers, partly because they haven’t been running long enough, says Harvard Medical School’s Michael Barry, in an editorial accompanying the two studies, published online today in the New England Journal of Medicine.
Prostate cancers grow so slowly — and are so rarely fatal — that there haven’t yet been enough deaths in the American study for doctors to know whether the test saves lives. The American study followed men for seven to 10 years. The European study followed men for nine years.
The American study found there were just as many deaths among men who were assigned to screening as among those who weren’t. In fact, there were slightly more deaths among those assigned to be screened, although this could have been due to chance.
The European study found that screening reduced the risk of death by about 20% — which Barry calls “at best a modest effect,” given that doctors would have to screen more than 1,000 men for 10 years to save one life.
Q. So should men still be screened or not?
A. Experts disagree.
Men at high risk should still get PSA tests, says the American Cancer Society’s Otis Brawley.
These include men with strong family histories and certain medical problems, such as lower urinary track symptoms like frequent urination that wakes them up at night.
“My greatest concern is that if we don’t handle this thing appropriately, we can hurt a bunch of people,” Brawley says. “There is a group of men who should be getting PSA and who might not because of what they hear.”
Given that prostate cancers grow so slowly — and because the studies found little to no benefit within the first decade of the study — older men with life expectancies under 10 years can probably skip the PSA safely, says Gerald Andriole of Washington University School of Medicine, lead author of the American paper.
His advice is in line with a recent recommendation from the U.S. Preventive Services Task Force, which in August recommended against giving the PSA to men over age 75. At that time, the task force said there wasn’t enough evidence to advise younger men to get screened.
“Knowing whether PSA testing reduces mortality may revolutionize how we screen for prostate cancer in the future,” says Howard Sandler, an official with the American Society of Clinical Oncology and a noted prostate cancer expert at Cedars Sinai Hospital in Los Angeles.
“Today’s studies provide some hints, but we still don’t have the full picture. We need to be patient, and men should continue to weigh the risks and benefits of regular PSA screening with their doctors until these studies are mature enough to give us definitive answers.”
Q: Why shouldn’t older men be screened?
A: Because they’re more likely to be hurt by the test than helped, said Michael LeFevre, a family physician and member of the task force, in an interview when the recommendation was were made. That’s because it might take a decade or more for prostate cancer to prove deadly. By that point, older men are likely to have died from something else.
Q: But isn’t cancer always deadly?
A: Not necessarily, Brawley says. And, in the case of prostate cancer, not usually. Most prostate tumors grow so slowly that they’re almost harmless. The task force notes that about half of prostate cancers don’t even need to be diagnosed, because they’ll never cause symptoms.
Q. How could screening hurt you?
A. While a blood test poses little risk, that simple blood test can lead to big-time treatments, such as surgery, radiation, or even hormone injections, which doctors describe as “chemical castration.” Up to one in 200 men actually die from treatment, rather than their tumor, according to the task force.
Q. How common are side effects?
A. Each treatment option poses different risks, says Gil Welch of Dartmouth Medical School, who worked on the American study.
The Prostate Cancer Outcomes Study, published in 2000, shows that about half of men who have surgery have some kind of sexual dysfunction, Welch says.
About a third of men who have surgery have some incontinence or have problems urinating.
Radiation therapy poses a greater risk of rectal problems.
About a third of those who have radiation have pain during bowel movements or chronic diarrhea, Welch says. Some doctors argue that rates of these problems have declined since that study was published, he says.
Q: Screening advocates often say that early detection saves lives. Isn’t that true?
A: Not for all cancers.
Early detection clearly saves lives in the case of cervical, breast, and colorectal tumors.
But not all cancers are alike. Pap tests and colonoscopies allow doctors to actually prevent cancer by catching precancerous lesions when they’re small and less dangerous.
Prostate screening, at least at this point in time, can’t do that.