CHICAGO - A prostate cancer study that could change practice found that widely used hormone-blocking drugs did not improve survival chances for older men whose disease hadn't spread.

In fact, men given the drugs alone were slightly more likely to die of prostate cancer during the next six years than men who'd gotten medical monitoring but no or delayed treatment, another common treatment approach.

The study involved nearly 20,000 Medicare patients with prostate cancer that hadn't spread. A surprising 41 percent got only drug treatment, in shots or implants, showing that the therapy has become a popular alternative to surgery and radiation, the study authors said.