Do you know when your PSA was first detectable (>0.1), what that value was, and how long it took to double that value. The very long time (15 years) to recurrence is in your favor, but the PSA doubling time is important data for making a decision of ADT/no ADT.

Given that you are intermediate risk (3+4) and given your age, I think you are right to explore the question about ADT along with RT. This is a big gray area and your personal life priorities should factor into any final decision along with medical best practices. Find an oncologist that will work with you in that regard. Many oncologists will almost reflexively recommend the ADT+RT route without considering patient priorities (I speak from experience). There are several studies that support that approach, so it is not unreasonable. But there are also docs who will not recommend ADT as part of a salvage therapy until PSA is greater than 0.5. Unfortunately, your PSA has exceeded that threshold, a complicating factor that weighs in favor of ADT.

I do completely agree with heavyphil—when you do RT, hit the pelvic lymph nodes prophylactically.

Last year I had a local recurrence, ten years after a RARP. I was also Gleason 3+4. In my case, a small nodule was detected during a DRE, and my PSA had risen to 0.11 after ten years of being undetectable (< 0.1). PSMA PET scan confirmed that the nodule was cancerous and found no evidence of distant mets. I got opinions from three oncologists. Two recommended IMRT plus at least 6 months ADT, and one (an RO) was fine with just RT. I scoured the medical literature and listened to many video presentations by top docs. In the end, I decided that the risks outweighed the benefits of ADT in my case and did 38 sessions of IMRT without ADT (I turned 73 during treatment). But, I will say that if my PSA would have been 0.7 instead of 0.11, I might have made a different decision. I would have put a lot of thought and questioning into it, all the same.

When I made my decision to forgo ADT, I strongly considered that I have a family history of heart disease, diabetes and dementia. ADT is a documented risk factor for all three of those things. On the other hand, I do not have a family history of PCa. And yes, studies clearly show that ADT works synergistically with RT, and can achieve better outcomes at five years, but when it comes to overall survival, studies are less clear about that. This includes the much heralded SPPORT trial which found no overall survival benefit of adding ADT to RT.

Best wishes moving forward.