Teriparatide in individuals with a prior history of radiation therapy-a case series

Teriparatide is a highly effective anabolic therapy for use in patients with osteoporosis at elevated fracture risk but carries a warning about an increased risk of osteosarcoma based on findings from pre-approval animal studies. Since approval, follow-up of individuals treated with teriparatide has not shown an increased risk of osteosarcoma, but it is still recommended to avoid teriparatide in patients with risk factors for osteosarcoma. One such risk factor is radiotherapy; deciding whether to use teriparatide therapy in patients at high risk of fracture but with a history of radiotherapy is therefore a frequent clinical problem.

We sought to identify whether clinicians are using teriparatide in patients with a history of radiotherapy despite the warning and to explore the rationale for this choice. Herein, we describe six cases where the likelihood of fracture, osteosarcoma, and the benefits of teriparatide treatment are assessed to determine the appropriateness of prescribing teriparatide in the setting of prior or concurrent radiotherapy.

All six patients had severe osteoporosis with limited treatment options. For those who completed 2 years of teriparatide, no further fractures during the follow-up period have occurred, and improvements in bone density (as measured by dual-energy X-ray absorptiometry) were observed.

Despite radiotherapy being a relative contraindication to teriparatide use, there may be a role for teriparatide in select cases where osteoporosis is complex and severe and where other treatment options are not suitable or have been exhausted. The risks vs. benefits of prescribing teriparatide in this population should always be carefully considered, and both the patient and treating oncologist should be educated on the potential risk of osteosarcoma development when teriparatide is continued during radiotherapy.