Trends in Radiation Fractionation for Bone Metastases: A Contemporary Nationwide Analysis.

BACKGROUND: Radiation therapy remains an important palliative tool for patients with bone metastases. Guidelines from ASTRO have recommended the use of fewer fractions based on randomized data. We used the National Cancer Database (NCDB) to examine trends in radiation fractionation for patients with bone metastases. METHODS: We queried the breast, prostate, and NSCLC NCDB datasets from 2010-2015 for patients with bone metastases at time of diagnosis receiving bone-directed radiotherapy of 8 Gy/1 fraction, 20-24 Gy/5-6 fractions, 30 Gy/10 fractions, or >30 Gy/10 fractions. We tabulated baseline characteristics and multivariable logistic regression was used to identify predictors of single fraction treatment. RESULTS: We identified 17,859 patients meeting the above criteria. The median age was 67 and the majority (67%) had primary prostate cancer. Most patients (62%) received spine treatment. Single fraction treatment increased over time, from 3% in 2010 to 7% by 2015. Use of more protracted courses (>30 Gy/10 fx) decreased from 34% to 15% over the same interval. Thirty gray in 10 fractions remained the most commonly utilized regimen (50-60% of cases).. Predictors of single fraction treatment included increased age, no systemic therapy, increasing distance from facility, treatment at an academic center, non-spine/non-skull metastasis, and more recent treatment year. CONCLUSIONS: Use of single fraction radiation for bone metastases has risen steadily but still accounts for <10% of palliative courses. The use of more protracted regimens has decreased significantly, although 30 Gy in 10 fractions remains the most widely used.