We've had threads in the past where it has been noted that testosterone production falls off with age. A rather high percentage of deadly prostate cancers are testosterone-dependent for growth, particularly in their early years. Thus, older males have a substantially reduced risk. Coupling that with the likelihood of bad outcomes from unnecessary treatment decisions that would likely follow suspicious results from a (dubious) PSA test, and guidelines that make it more difficult/expensive to use the PSA test for older folks are pretty valid, IMO.