Disparities in Patterns of Conventional Versus Stereotactic Body Radiotherapy in the Treatment of Spine Metastasis in the United States.

INTRODUCTION

The improved survival of patients even with metastatic cancer has led to an increase in the incidence of spine metastases, suggesting the need for a more aggressive palliative treatment than conventional external beam radiation therapy (cEBRT). Consequently, spinal stereotactic body radiation therapy (SBRT) has increased in popularity over the past decade. However, there has been no comparison of patterns of usage of cEBRT versus SBRT in the treatment of spinal metastases in the US.

METHODS

The National Cancer Data Base (NCDB) from 2004-2013 was used for analysis. cEBRT was defined as 30 Gy in 10 fractions, 20 Gy in 5 fractions, or 8 Gy in 1 fraction. SBRT was defined as 25-32 Gy infive5 fractions, 24-32 Gy in 4 fractions, 20-32 Gy in three fractions, 14-32 Gy in 2 fractions, or 14-24 Gy in 1 fraction. Single and multivariable associations between patient demographic and cancer characteristics and type of radiation were performed.

RESULTS

From 2004-2013, 23,181 patients with spinal metastases in the United States received cEBRT, while 1,030 received SBRT as part of their first course of treatment. Most patients (88%) received 10 fractions of radiation. Multivariable analysis suggested that non-Medicare or private insurance (adjusted OR 0.4-0.7), African-American race (adjusted OR = 0.8, 95%CI = 0.7-1.0), age 65+ (adjusted OR = 0.8), living in a region with lower population (adjusted OR 0.7), earlier year of diagnosis (OR = 0.9), and receiving treatment in a non-academic/research facility (adjusted OR 0.6) were associated with cEBRT. After controlling for other variables, regional education level was no longer significantly associated with cEBRT.

CONCLUSIONS

Most patients with spine metastases were treated with cEBRT, usually with 10 fractions. Receipt of SBRT was significantly associated with race, insurance, geography, population, type of treatment facility, and year of diagnosis, even after controlling for other factors. These findings raise questions about disparities in access to and delivery of care that deserve further investigation.