Background: Postmarketing safety surveillance studies can be challenging to implement, especially when the outcome of interest is a rare cancer. Interim results from an ongoing study to examine adult osteosarcoma (occurring at a rate of 2.7 cases per million population in adults in the US) using data linkage with populationbased state cancer registries are presented.
Objective: To provide a study update of the voluntary Forteo Patient Registry, designed to estimate the incidence of osteosarcoma in patients who have received treatment with teriparatide (Forteo).
Methods: This surveillance study is a multiyear, prospective registry in the US designed to link information from adult patients with a history of teriparatide use who enroll during the 10-year recruitment period (initiated in July 2009) with participating state cancer registries annually for 15 years (through 2024) to identify osteosarcoma cases diagnosed after patients started treatment. Patients are invited to participate through multiple pathways of communication and enrollment is tracked by pathway type when possible. The linkage algorithm uses enrollment information (name, birth date, sex, address, telephone number, race, ethnicity, and last 4 digits of social security number) provided with patient consent to match with participating cancer registries.
Results: In October 2014, the 5th annual linkage was completed with 42,544 patients enrolled in the Forteo Patient Registry (equivalent to 100,400 person-years of follow-up adjusted for mortality) linked to 3,171 adult cases of osteosarcoma from 41 state cancer registries, (covering 92% of the US population aged 18 years and older) and no matches were found. The most common pathway leading to enrollment was the medication packaging (60%) followed by the starter kit (21%).
Conclusions: Although no incident cases of osteosarcoma among patients in the Forteo Patient Registry have been identifi ed through the linkage process, our ability to draw conclusions after 5 years about the incidence of osteosarcoma among teriparatide users is limited due to follow-up time currently available.
