That's why it should be an individual decision.
Prostate cancer treatment is rather effective in early cancers. Here is a Scandinavian study:
http://www.medscape.com/viewarticle/750994The difference between radiation treatment and watchful waiting really shows up. However with a median age at diagnosis between 67 and 68, you do not expect to see much of a 15 year mortality difference. But note 65% progression-free survival versus 36% for the radiotherapy group.
The reason why I would not be very aggressive with prostate cancer treatment if it is detected late is that you are buying many less years of life for the unpleasantness. For example, I have no intention of going through breast cancer screenings when I am 75.
Many men won't seek treatment. Those men who have decided not to shouldn't be forced to get PSAs. Men who would seek treatment should get them. It's up to the individual. Most men I have known detected by PSA have waited for a couple of months and had retesting and/or had other risk assessments done before even opting for a biopsy. In my admittedly limited experience, rapidly rising PSAs HAVE had a high predicting factor for aggressive tumors, and larger tumors have been far more aggressive.
If the cancer seems very static, or the PSA isn't going anywhere, or the PSA is high but free PSA is also high, then many men will choose the watchful waiting route. It's not as if Prostrate Cops kidnap you and perform a biopsy willy-nilly. Also, radiotherapy in early-stage cancers does appear to offer benefits comparable to more radical treatments and it often has less side effects.
All of those unpleasant side effects of treatment are much worse when aggressive cancers aren't treated pretty early, and the side effects of a cancer doomed to grow fast is going to be a hell of a lot worse than the treatment. To my mind, early PSAs often offer a way to assess significance of rising PSAs later, especially because early PSA levels tend to predict later PSA levels. You are really watching for the rapid rise. That's why I find this report somewhat frustrating. The European Randomized Study of Screening for Prostate Cancer did find a 20% mortality reduction with PSA testing after 9 years, but they set the PSA bar lower. This suggests that the real problem with PSA testing is that it is being used improperly - detecting aggressive cancers early enough to reduce mortality requires a more complicated methodology plus use of other testing to screen out a lot of the false positives without doing biopsies at too high a rate.
For men with the risk factors that my brothers have, more frequent testing beginning earlier and intervention at a lower PSA level apparently confirmed with a low free PSA rate, and monitoring for rapid rise at lower PSA levels backed by screening for other causes like inflammation almost certainly will reduce mortality and will produce better quality of life results via much earlier treatment that has less associated loss of function.
The bottom line is that one size does not fit all - that's the point I am making.
Most women will eventually get microscopic breast cancers if they live long enough. Most men will get microscopic prostate cancer if they live long enough. The cancers that will steal decades of life are the fast-moving ones that start earlier.