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

Radiation therapy remains an important palliative tool for patients with bone metastases. The guidelines from the American Society for Therapeutic Radiation Oncology recommend the use of fewer fractions based on randomized data. We used the National Cancer Database to examine trends in radiation fractionation for patients with bone metastases.

We queried breast, prostate, and non-small cell lung cancer in the National Cancer Database from 2010 to 2015 for patients with bone metastases at the time of diagnosis who received bone-directed radiation therapy of 8 Gy in 1 fraction, 20 Gy to 24 Gy in 5 to 6 fractions, 30 Gy in 10 fractions, or >30 Gy in 10 fractions. We tabulated the baseline characteristics, and a multivariable logistic regression analysis was used to identify predictors of single-fraction treatment.

We identified 17,859 patients who met the study criteria. The median patient age was 67 years, and the majority of patients (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 in 10 fractions) decreased from 34% to 15% over the same interval. The most commonly used regimen (50%-60% of cases) remained 30 Gy in 10 fractions. Predictors of single-fraction treatment included increased age, no systemic therapy, increasing distance from facility, treatment at an academic center, nonspine/nonskull metastasis, and more recent treatment year.

Use of single-fraction radiation for bone metastases has increased 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 regiment.