Have you been having any treatment at all in that time, or oncology reviews?  My husband (75) has had it for 10 years, controlled by Prostap3 hormone injections  plus abiraterone latterly as there was a slight spread.  Last year his PSA went from 0.7 to 90 in a few months due to mets in lymph nodes so he was put on 10 cycles of chemotherapy.  PSA came down and is currently 7 after 8th cycle.  Alternatively, RT also reduces it.  There are several options these days to prolong life as long as possible.  Your oncologist would be the best person to advise what would be best for you.