Diagnosing cancer in time to treat it effectively is crucial. But the issue is complicated by the fact that all prostate cancers are not created equal. Some are very slow-growing, and never need treatment; others can be fatal within a matter of months after they are diagnosed. So it's just as important to find cancer early as it is to know which kind of cancer - the "good" or the "bad" - has been diagnosed.
Research at the Brady Urological Institute at Johns Hopkins has established guidelines on which men can afford to "watch and wait," and to flag the men at the other end of the spectrum (those with aggressive cancers that will almost certainly be lethal if not treated immediately).