Doctors have long debated how and whether to treat early cases. Dr. Richard Greenberg, of Fox Chase Cancer Center in Philadelphia, says "there clearly is a benefit to getting the cancer out in the younger population."
But the benefit may depend on how a man is diagnosed.
About 95 percent of the cancers in the study were found because they were causing symptoms. In the United States, however, most of the cancers are found after a PSA blood test suggests a problem, long before symptoms appear.
Most of these cancers will not prove life-threatening, but there's no surefire way to tell which ones will, so many men get treatment they may not need.