Basically, none.

More males die from heart/lung/liver/kidney/alzheimer/accidents/other
diseases
than from prostate cancer, which is often detected only during an autopsy.
Put
another way, many more men die WITH undetected prostate cancer than from
it.

However it is recommended that all males have a PSA blood test every year
after the age of 50, and a biopsy if any PSA test is high - some doctors
say
if it's over 4, others say over 5 or 6.

If the biopsy is positive and you're under 60, you may want to follow your
doctor's suggestions.

Between 60 and 70, follow your heart and mind.  How's your overall health
elsewise?  How long do you expect to live (not how long do you WANT to
live)?  Would intervention improve the quality of live during your
remaining
years?

Over 70, it's really up in the air whether any treatment/surgery would be
beneficial and add to the quality of life.