Utilization Patterns of Single Fraction and Short Course Radiotherapeutic Schedules in the Management of Bone Metastases

Purpose/Objective(s) Bone metastases are a common oncologic development occurring in approximately 60-70% of patients with advanced malignancies. Historically, bone directed radiotherapy at doses of 30 Gy delivered over 10 daily fractions have been commonly employed. However, prospective randomized data suggests equivalent pain relief with shorter course regimens. As such, the ASTRO Choosing Wisely Campaign was created in an effort to encourage clinicians to consider shorter course palliative regimens in patients with uncomplicated bone metastases who have a limited prognosis. We performed a retrospective analysis of our large, integrated health system in an effort to assess utilization patterns of short course and single fraction radiotherapy regimens over the last 5 years. Materials/Methods We queried our internal radiation oncology electronic medical record (MOSAIQ®) from 2016-2020 for patients with bone metastasis who received palliative bone-directed radiotherapy in our network. Patients receiving Medicare approved palliative courses of radiation (30 Gy/10 fractions, 24 Gy/6 fractions, 20 Gy/5 fractions, 8 Gy/1 fraction) were included, as well as, patients receiving > 10 fractions. Treatment site was defined as academic (n = 2) versus community (n = 12). Short course treatment was defined as radiation treatment courses of ≤ 6 fractions, whereas long course included patients receiving ≥ 10 fractions. Patients were subdivided into quartiles based upon age and site of disease (spine, hip/pelvis, extremity, and other). Physicians were grouped according to their year of radiation oncology residency completion (before versus after 2010). Multivariable logistic regression analysis was completed to identify predictors of short course and single fraction treatment. Results We identified 1,004 patients with 1,768 bony metastatic lesions meeting the above criteria. The median patient age was 68 years (Interquartile range: 61-76 years). The spine was the most commonly treated site (46%) followed by pelvis/hip (26%), extremity (15%), and other (13%). Use of short course treatment increased over time from 40% in 2016 to 50% in 2020. Single fraction treatment also increased over time from 7% in 2016 to 11% in 2020. Predictors of short course treatment included: treatment at an academic center, more recent treatment year, patient age > 76 years old, non-spine anatomic site. Predictors of single fraction treatment included: treatment at an academic center, treating physician residency completion after 2010, patient age > 76 years old, and treatment to extremity or other site. Conclusion Rates of short course and single fraction bone-directed radiotherapy utilization increased within our integrated health system over time. Treatment receipt at an academic center was associated with both short course and single fraction regimens. Physicians completing residency after 2010 were more likely to deliver single fraction therapy.