Jan. 6, 2012 -- Routine screening for prostate cancer does not lower the risk of dying from the disease, according to new study results, reigniting the controversy over the benefits of annual testing.
In a follow-up to previously reported data, researchers led by Dr. Gerald Andriole, chief of urologic surgery at Washington University School of Medicine in St. Lous, found that men who underwent yearly screening for prostate cancer, which included a digital rectal examination and a blood test for prostate-specific antigen (PSA) levels, had the same chance of dying from prostate cancer as men who were tested less often.
The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial followed nearly 77,000 men ages 55 to 74 for 13 years. Men in the intensive screening group had a PSA test every year for six years and a rectal examination annually for four years.
The researchers first reported there was no difference in mortality between the two groups after following the men for 7 to 10 years, but after criticism that the men should be followed longer since prostate cancer is a slowly progressing disease, they extended the follow-up to 13 years and got the same result.
"The finding is along the lines that routine mass screening of men is probably not very beneficial as far as reducing the chance of dying from prostate cancer," Andriole said. But he also stressed that some men -- those who are young and healthy, have a long life expectancy or have a strong family history of prostate cancer -- will benefit. African-American men, who are twice as likely to die from prostate cancer as Caucasian men, should also be regularly screened.
The value of annual PSA screening has been hotly debated by the medical community. Some say regular testing has saved many lives; others argue proof of its benefits just isn't there. In December, the U.S. Preventive Services Task Force issued draft recommendations saying the available data are unclear to support routine screening in men younger than 75. They also recommend against screening in men 75 and older.
Experts told ABCNews.com that the latest findings from the PLCO don't lend much to either side of the argument because the study contained numerous flaws. One of them, they explained, is because although one group was screened annually, more than half of the men in the other group did get occasional screening as part of their usual medical care, making it difficult to figure out the true effect of screening.
"There was also a large study in Europe that had significant flaws as well, and that study showed a mortality benefit, so the two largest studies had these similar flaws and came to different conclusions," said Dr. Durado Brooks, director of prostate and colorectal cancers for the American Cancer Society. "There are no clear answers to take away from this."
Even medical organizations have different recommendations on prostate cancer screening. The American Urological Association recommends that all men 40 and older be offered a screening test if they want it, but the American Cancer Society says while there may be some benefit to screening, it can also be harmful, so men should make an informed decision with their doctor based on personal beliefs and whether they are at risk.
Screening Has Potential Pitfalls
"The test is far from perfect, there are many false positives because of other conditions that can elevate PSA levels, such as an enlarged prostate," said Dr. David Penson, director of urologic surgery at Vanderbilt University Medical Center. "That can lead to a cascade of events -- prostate biopsies are not comfortable and carry a risk of infection and a small risk of dying. "
Penson also said there are a fair number of overdiagnosed tumors, and people may have an inactive cancer that doesn't require aggressive treatment.
Since there are no good tools to determine whether someone's prostate cancer is an aggressive form or not, men opt for treatment such as radiation or surgery, which can also have numerous complications.
"But the benefit is that if you happen to catch a moderate or high-grade cancer early, it can be treated and kept in remission," Penson said.
Despite the arguments against routine PSA testing, it's exactly that benefit that Dr. William Catalona emphasizes when he voices his strong support for regular screening for many men.
"There's been a 40 percent decrease in the death rate from prostate cancer in the U.S. and if PSA screenings are stopped, it would push back the progress that's been made," said Catalona, professor of urology at Northwestern University's Feinberg School of Medicine. "I don't think every person should be screened, but my general feelings are that men should start PSA testing in their 40s just to get some data to look at, and if it starts to rise and show a trend, they need to make individual decisions about treatment."
He also criticized the PLCO study as well as the studies he said the U.S. Preventive Services Task Force used to make their recommendations.
"They took flawed studies and combined them with better studies, and the results from the flawed studies diluted the benefits of the good ones."
While experts continue the back-and-forth discussion on prostate cancer screening, Andriole said he and his team plan to continue tracking the participants for a couple more years. He also said he hopes to work with European researchers to pool their analyses.
Brooks hopes that ultimately there will be tools other than the PSA test available.
"We need better tools for screening -- we need tools to ascertain more clearly what cancers are going to be the fast-growers and likely to cause more harm," he said.