Yes, I would irradiate the pelvis in a patient with high risk prostate cancer for whom elective pelvic nodal irradiation is indicated, even in the setting of osteoporosis and prior sacral insufficiency fractures. The bigger risk to bone health in these patients is the need for ADT, rather than pelvi...

I treat lots of prostate patients and I’ve not encountered this. That said, yes. 

It depends on why are they in the "high" risk group? For example, if they were a Gleason 9-10, I'd treat the pelvis, otoh, if they were a T3a or for example, were Gleason 6 but had a PSA >20, maybe not. My first step would be to obtain a PSMA PET scan and see what it showed. If any nodes seemed ...

Most of the patients I have seen over the years with radiotherapy related pelvic insufficiency fractures had cervical cancer but the literature notes that patients with prostate cancer are not immune. Some of these fractures are only known because of imaging while others cause life changing pain. If...