PURPOSE: During preclinical testing, teriparatide caused a dose-dependent increase in the incidence of osteosarcoma in rats. This study estimated the incidence rate ratio of osteosarcoma among patients aged ≥65 years treated with teriparatide versus a matched-comparator cohort.
METHODS: This population-based comparative-cohort study matched exposure details for each teriparatide user, identified via Medicare Part D prescription claims, and up to 4 comparators based on age, sex, zip code, date of claim for filled prescription, and number of unique therapeutic classes dispensed. Outcomes were identified via linkage with participating cancer registries. All United States (US) state cancer registries were invited to participate.
RESULTS: Overall,153,316 patients in the teriparatide cohort and 613,247 in the comparator cohort were linked to 811 osteosarcoma cases from 26 participating state cancer registries (68% of US patients aged ≥65 years diagnosed 2007-2014). Analysis on a subset of cohorts revealed they were balanced for known osteosarcoma risk factors and Charlson comorbidity index. Mean duration of teriparatide treatment was 10 months. No osteosarcoma cases were observed in the teriparatide cohort; the incidence rate in the comparator cohort was consistent with the background incidence rate among adults aged ≥65 years. The incidence rate ratio was 0.0 (95% confidence interval, 0.0-3.2).
CONCLUSIONS: For US patients aged ≥65 years, incidence of osteosarcoma among those treated with teriparatide ranges from 0 to 3.2 times the incidence of osteosarcoma in those treated with other medications. Given low incidence of osteosarcoma, this range of effect is inconsistent with a large absolute increase in osteosarcoma risk.
