Studies cast doubt on prostate cancer screenings
The tests rarely save lives, researchers say, and treatment can cause more harm than the potential tumor.
By Thomas H. Maugh II
March 19, 2009
Whether to screen men for prostate cancer has been a controversial topic for at least 20 years. Many clinicians have believed that finding a tumor early and cutting it out is the best possible way to treat prostate cancer, just as it is for most tumors.
Critics of the screening have argued that many prostate tumors grow so slowly that the patient is likely to die of other causes before the tumor becomes a threat. They contend that early treatment can cause more damage than leaving the tumor alone.
Now, two major and long-awaited studies show that screening men for prostate cancer provides little or no benefit in saving lives and can lead to painful, debilitating and expensive medical treatments without any obvious benefit.
The newest findings, released Wednesday, would seem to support the stance of the critics. But doctors -- and patients -- are cautious. And though the new results may seem definitive, experts say they're still not clear-cut enough to recommend against screening for prostate cancer. As such, the decision to screen is likely to remain one made by doctor and patient, with both unsure whether or not the test is prudent or risky.
The first report, on an American study of 76,000 men, found no survival benefit from screening. The second report, on a European study of 162,000 men, found a 20% reduction in deaths -- which was only barely significant statistically because of the small number of deaths on which it was based. Both reports were published online in the New England Journal of Medicine.
Even with the reduction found in the European trial, it was necessary to screen 1,400 men and treat 48 cancer cases to save one life.
"What the European study tells us is that, if you are a man who chooses screening, you are 47 times more likely to be harmed . . . than to have your life saved," said Dr. Otis W. Brawley, chief medical officer of the American Cancer Society.
In contrast, only 11 women with breast cancer must be treated to save two lives, he said, and the treatment's side effects are much less severe. Men suffer long-term impotence and urinary incontinence, while women can get reconstructive surgery and suffer fewer permanent effects.
"If a man is really worried about prostate cancer, he should take that statistic under advisement and decide to get screened," Brawley said. "If he is not worried, he should decide to avoid screening."
The bottom line is that the studies "are not necessarily going to change practice much in the United States," said Dr. Howard Sandler of Cedars-Sinai Medical Center, a spokesman for the American Society of Clinical Oncology.
The papers "don't tell patients anything different from what we have been telling them," which is do it only if you are very concerned, added biostatistician Ruth Etzioni of the Fred Hutchinson Cancer Research Center in Seattle. "When you have a large controlled trial like these, it is usually the final word . . . conclusive. These are very unsatisfying."
Men more likely to seriously consider screening would be African American men or those with a family history of prostate cancer, two groups who face a higher risk of the disease. About 186,000 American men will be diagnosed with prostate cancer this year, and an estimated 28,660 will die from it, according to the National Cancer Institute.
Screening for the disease usually involves a prostate-specific antigen, or PSA, blood test and a digital rectal exam, in which a physician manually feels the prostate for any abnormalities. In the United States, a normal level of PSA is considered to be 4. Higher levels generally indicate the presence of a tumor, and rising levels indicate an aggressive tumor.
Since 1992, five years after the PSA test was introduced, U.S. death rates from prostate cancer have declined about 4% per year. Some attribute the decline to the test, while others say it is due to better treatment regimens.
No group currently recommends routine screening. Both the American Cancer Society and the American Urological Assn. recommend that men 50 years and older simply be offered the option of an annual test if they have a life expectancy of more than 10 years.
The U.S. Preventive Services Task Force, established by Congress to make recommendations about preventive care, issued guidelines last fall stating that men older than 75 should not be given the test. The group said there was not enough evidence of efficacy to produce guidelines for younger men.
The two studies released Wednesday in the journal and at the Stockholm meeting of the European Assn. of Urology were designed to give a definitive answer about the value of such screening. Both are interim reports, and researchers will continue to follow the subjects for several more years in hopes of producing a more definitive conclusion -- that is, results with less of a discrepancy.
The seven to 10 years that patients have been followed "is not long enough," Sandler said. "We know prostate cancer has a long natural history and that deaths can take 15 to 20 years after diagnosis."
But even if the studies were to be extended by an additional five years, they are not going to produce "a stunning result," Etzioni said, because the studies are unlikely to show the dramatic lowering in death rate that researchers had hoped for.
The teams promise more papers in which they will analyze the treatments and the quality of life for those who undergo therapy. Those results are likely to be more informative and "will color which way I would lean very heavily," said Dr. Glen Justice, director of MemorialCare Cancer Center at Orange Coast Memorial Medical Center in Fountain Valley.