Studies: Prostate PSA tests may do more harm than good

Prostate cancer screenings given to millions of American men each year have little or no effect on whether patients will die from the disease, according to two large studies released Wednesday.

Although the new trials produced slightly different results, both raise the question of whether early detection of prostate cancer - whose treatments can leave men impotent and incontinent - does more harm than good.

After nearly a decade of follow-up, American scientists leading a trial of 77,000 men found there were slightly more deaths among men who were randomly assigned to undergo annual screening for PSA (prostate-specific antigen) as there were in the comparison group. Because prostate tumors usually grow so slowly, however, doctors say there haven't been enough deaths yet to know whether that small increase is a real problem or due to chance.

Europeans leading a trial of 182,000 men found modestly more positive results, with screening tests reducing the risk of death by 20 percent. Those findings just barely meet the standards for a real trend, however, and were statistically very close to being due to chance, says the American Cancer Society's Otis Brawley.

"If screening is beneficial, it is beneficial in a very small way," says Brawley, who wasn't involved in either study.

Others say the test, which has been widely used for 20 years, may have hurt many men.

"It's likely that thousands of men have been helped, but many more thousands of men have been harmed," says Ruth Etzioni, who studies prostate cancer risk at Seattle's Fred Hutchinson Cancer Research Center but wasn't involved in either trial.

Scientists at the National Cancer Institute, which funded the American study, say they will need to follow men for several more years before they will know with certainty whether PSA screening saves lives in the long run. That's because most prostate tumors grow very slowly, so that very few men die within 10 years of diagnosis.

Physicians around the world had hoped these two long-running trials would provide clear-cut advice to patients, Etzioni says.

For now, doctors can advise one group of men - those with life expectancies under 10 years - that it's probably safe to skip the PSA, since they are likely to die of something else before a tumor would cause them any harm, says Gerald Andriole of Washington University School of Medicine, lead author of the American paper. A government panel issued a recommendation last August that men age 75 and over shouldn't be screened.