The odd of being diagnosed with PCA are really low if you never have a PSA test
http://www.prostatecancer-riskcalculator.com/seven-prostate-cancer-risk-calculatorsThere are very few PCA cases diagnosed under 50 years old (except those you see on HW) so the statistics are probably hard to develop with any accuracy. The chance of other causes of death is much greater and should be of more concern under 50.
If you run the first calculator above, it starts at age 55 and says around 6-7% for no history or urinary symptoms if that helps any.
Most “odds” calculators require age, race, PSA and DRE results to attempt a probability extrapolation as without that data, it is just a wild guess. Family history and race are big influences on the odds (2X) also.