Bcgallacher makes a very worthwhile point. "If prostate cancer is detected soon enough it is cureable - if too late it is only treatable".
Whilst PSA screening would seem to be far from perfect, it is certainly much better than no screening at all. My PSA test was a suggestion by my then current AME, as one had not been done for several years; no other symtoms of a looming problem. I was therefore surprised when my PSA reading was 5.9.
Obgraham's advice is to seek multiple opinions; I did, my GP, UK AME and Urologist. Luckily there was consensus over the options available to me.