Is history of radiation an absolute contraindication to using parathyroid hormone (PTH) analogues?

Hx of prior radiation was never a contraindication, it was a warning due to the known increase in osteosarcoma in patients who had prior radiation. A contraindication requires proof of harm. There was no data that radiation plus a PTH anabolic increased the risk of osteosarcoma. With the review of 15+ years of post-marketing safety data, the boxed warning was changed. There is now no limit of 24 months (the longest duration of exposure in the Phase 3 trial). I still think a good conversation re: osteosarcoma is warranted and should be documented but I personally have less concern about osteosarcoma.

Yes.

I believe past history of radiation is indeed one of the contraindications listed. Though this is largely based on theoretical concerns of increased risk of bony cancer in animal studies. I am not aware of any large set of human data that actually addresses this issue.