BACKGROUND: This study was initiated in 2003 at Forteo’s time of approval in the United States (US) to monitor for a potential association between teriparatide (an osteoporosis treatment) and osteosarcoma, which occurs in the US in adults aged 40 years or older at a background incidence rate of approximately 2.5 cases per million per year.
OBJECTIVE: To provide final study results, including descriptive characteristics of patients with osteosarcoma aged 40 years or older.
METHODS: All state cancer registries, plus targeted regional and comprehensive cancer registries in the US, were invited to participate in this patient-contact study. Incident cases of osteosarcoma diagnosed between January 1, 2003, and December 31, 2016, identified through cancer registries were reported to RTI once all requirements for releasing patient identifying information were met. Exposure to teriparatide was ascertained during telephone interview. Information about demographics, medication use prior to osteosarcoma diagnosis, and other possible risk factors for osteosarcoma were ascertained. Requirements necessary for contacting patients (patient-access pathways) varied among cancer registries from passive notification to active permission from the patient and/or physician.
RESULTS: As of September 30, 2018, 3,809 incident cases of osteosarcoma in patients aged 40 years or older were identified by 30 cancer registries. After cancer registries completed individual requirements to release contact information, 2,545 patients were available to be interviewed. Of these, interviews were completed for 1,165 patients (46%). The mean age at the time of diagnosis was 61 years of age, and more than half were men (53%). The most common ICD-O-3 morphology codes were for osteosarcoma NOS (71%) and Chrondroblastic osteosarcoma (13%). Of those interviewed, three patients reported use of teriparatide prior to diagnosis of osteosarcoma, which is within the expected range assuming no increased risk with treatment.
CONCLUSIONS: Drug safety surveillance studies that involve both a rare drug exposure and a rare cancer outcome require participation by many cancer registries. Results from this study indicate that, while resource-intensive, patient-contact studies with multiple cancer registries are feasible. Data from this study contributed to evidence about the long-term safety of teriparatide that is valuable to patients and physicians considering treatment with this product.
