My PSADT has changed from 36 mo. to 9 over last 2 yrs. Why now 7 yrs after SRT?

My PSADT was 36 months 2 years ago. It dropped to 18 months last year and just recently dropped to 9 months. I had RP 10 years ago and SRT 7 years ago. I had a large volume of G5 cells in one lobe. Is it possible that these are the source of my problems? Am I in trouble or can I just let things ride? I'm 81 years old, healthy and am my wife's caregiver. I really need to hang around another 10 years. Any ideas on what my options are? I see my urologic onc next week.

TA, Thanks for the reply. I really shouldn't be surprised at the recurrence since the MSK nomogram only gave a 25% chance of success.