Gilsenan A, Harris D, Reynolds M, McSorley D, Midkiff K, Jackson L, Muldavin B, Kellier-Steele N, Andrews E. Long-term cancer surveillance: results from the Forteo Patient Registry Surveillance Study. Osteoporos Int. 2020 Nov 5;32(4):645-51. doi: 10.1007/s00198-020-05718-0

SUMMARY: The Forteo Patient Registry estimated the incidence of osteosarcoma in US patients treated with teriparatide and enrolled in the study between 2009 and 2019. No incident cases of osteosarcoma were identified among patients registered, and the crude incidence rate was 0 (95% confidence interval [CI], 0–10.2) cases per million person-years.

PURPOSE: The prospective, voluntary Forteo Patient Registry was established to estimate the incidence of osteosarcoma in patients who have received treatment with teriparatide (Forteo).

METHODS: Information on US adults prescribed teriparatide and enrolled in the Forteo Patient Registry 2009–2019 was linked with data from participating state cancer registries annually (2010–2019) to identify incident osteosarcoma cases using a standardized linkage algorithm. Teriparatide exposure was ascertained from self-reported data that included teriparatide initiation and demographics necessary to complete linkage. Osteosarcoma cases diagnosed on or after January 1, 2009, were identified by participating state cancer registries. The crude incidence rate (IR) and standardized incidence ratio (SIR) of observed cases to the expected number of cases adjusted to the background rate (3 per million person-years) and corresponding 95% CIs for the occurrence of osteosarcoma were calculated whereby the cumulative amount of person-time observed was adjusted for mortality.

Data for 75,247 enrolled patients (representing 361,763 cumulative person-years) were linked to each of 42 participating state cancer registries (covering 93% of the US population), which included information on 6180 cases of osteosarcoma. No matches with incident cases of osteosarcoma following registry enrollment were found. The crude IR was 0 (95% CI, 0–10.2) cases per million person-years and the SIR was 0 (95% CI, 0–3.0).

CONCLUSIONS: The ability to draw conclusions about the incidence of osteosarcoma among patients participating in the registry was limited due to the smaller than expected amount of patient follow-up time and the fact that no cases were identified.

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