Effects of Proton Therapy Without SpaceOAR

I have a gleason of 7 (4+3) with an adjusted PSA of 15 (doubled 7.5 due to longtime finasteride use) and an MRI showing extraprostatic extension. Fortunately, a PSMA-PET showed no spread outside the prostate. I've begun lupron ADT therapy and will begin 28 proton radiation therapy sessions in a week. A spaceOAR was not indicated given the extraprostatic extension so I'm wondering of others experiences and impact on rectal functioning throughout therapy and after.