Prostate Cancer Screening Fails to Provide Definitive Benefits
In one, an American research team detected no reduction in deaths with screening. In the other, a European group reported a 20 percent reduction in mortality among those tested for prostate cancer. Both studies, published yesterday on the New England Journal of Medicines Web site, left enough questions about routine screening that Otis Brawley, chief medical officer of the American Cancer Society, said, “only a man can decide with his doctor.”
Prostate cancer was the most common malignancy in U.S. men last year with 186,320 new cases, and the second deadliest with 28,660 deaths, according to the American Cancer Society. Blood tests measure prostate specific antigen, or PSA, a protein that rises with age and benign enlargement as well as cancer. Screening showing elevated levels may lead to some slow-growing cancers getting unnecessary treatment that risks impotence.
“These trials dont tell men what to do. Its very disappointing,” said Ruth Etzioni, senior investigator at the Fred Hutchinson Cancer Research Center in Seattle, Washington, who wasnt involved in the studies. “There is potentially an upside to screening. There is also a downside. We knew that before.”
U.S. Study
The U.S. team, led by Christine Berg of the National Cancer Institute, reported results of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial in 76,693 men ages 55 to 74 who were tested and followed for an average of 7 years. Half the volunteers received annual screening and the control group received their doctors usual care. The death rate did not differ between the groups.
The U.S. study results were clouded because about 40 percent to 50 percent of the patients in the control group received prostate cancer screening as part of their regular medical care, said the leader of the European research, Fritz Schroder of the Erasmus Medical Center in Rotterdam, in an e- mail yesterday.
The European study observed 162,243 men ages 55 to 69 for an average of 9 years. Half were offered screening every four years. The results found PSA screening reduced the death rate by 20 percent — along with a risk of over-treating the screened patients.
Early Detection
“We now know that screening does reduce prostate cancer mortality. This clearly shifts the balance of previous professional advice toward early detection,” said Schroder, who led a team of 23 researchers in the European study.
After nine years of observation, European doctors found seven fewer deaths from prostate cancer for every 10,000 men they tested.
“This means that 1,410 men would need to be screened, and 48 additional cases of prostate cancer would have to be treated to prevent one death from prostate cancer,” Schroder wrote in the journal.
The European research analyzed seven separate studies with varying approaches. The U.S. and European studies also differed in the demographic groups tested. The European volunteers were overwhelmingly white, while 15 percent of the U.S. participants were ethnic minorities.
Studies Will Continue
“This is not the final word. We need longer follow-up,” said Berg, senior author of the U.S. study and chief of the early detection research group of the National Cancer Institutes Division of Cancer Prevention.
The U.S. study found 500 more cancers, but no fewer deaths, in the group assigned to get annual screening than in the group that received usual care after seven years. Berg said she wants to review the data after all the men have been observed for 13 years.
Men face conflicting advice about prostate cancer screening. The U.S. Preventive Services Task Force says there isnt enough evidence to assess the balance of benefit and harm of PSA screening in men younger than 75, and recommends against screening in men 75 and older. The American Cancer Society recommends that screening be offered to men with an average cancer risk at age 50, and men at high risk at 45, with discussion of risks and benefits.
Screening Drawbacks
The European study leader Schroder acknowledged the cost of saving a life was “a considerable amount of overdiagnosis and overtreatment.”