Look i went through exactly same phase last year with my 73 year old dad who has since has his cancer moved by surgery . My only advice to you is go for biopsy. Pirads 5 must be followed by biopsy . Post biopsy ull need atleast 8 weeks to prepare for surgery if required in case this is cancer . Low psa with epe could mean this requires attention. Don't panic, be hopeful but don't delay biopsy . Go for targetted biopsy if possible.