@sbd
It is not mandatory to have an ARSI but if your PSA starts rising, it is the main solution right now for you to keep your PSA down.

Many people who have prostate cancer and are on ADT, which keeps their testosterone almost undetectable, still become castrate resistant And require an ARSI or their PSA will start rising. That happened to me, First, I went on Zytiga Which kept my PSA down, but not undetectable for 2 1/2 years. I moved on to Nubeqa Which is kept me undetectable for two years. I know many people that have moderate testosterone levels and are on Nubeqa Alone, and it keeps their PSA undetectable.

An ARSI like Nubeqa Has very few side effects and doesn’t pass the blood brain barrier so it doesn’t cause brain fog and keeps the PSA down quite reliably.