We obviously don't know all the specifics of your diagnosis but in general I think your choice of surgery for Gleason 9 with no evidence of spread is relatively common. Some doctors recommend surgery in cases like yours to hold radiation back as a second treatment in the event that there is any return or progression of the disease; having radiation as the first treatment is usually considered to rule out surgery later leaving fewer options for treatment.

I was also diagnosed as Gleason 9 based on a saturation biopsy (MRI had indicated no lesions but an ExoDx urine based screening test had indicated a 36% probability of treatable cancer so my doctor recommended going ahead with the biopsy and I am very glad he did.) Two of the 24 biopsy samples showed a very low percentage of Gleason 9 cancer in each sample. I had a RALP and the pathology report on the full prostate following surgery downgraded my case to Gleason 7 (4+3 with tertiary 5). This illustrates another benefit of surgery: the entire prostate can be analyzed after removal and a more complete report on the full extent and grade of whatever disease is present can be determined. I am 18 months post surgery and have PSA checks every 3 months and all have been undetectable.

Based on what you have told us about your diagnosis I feel you are on the right course with your current plan of treatment and wish you all the best.