Abstract C001: Palliative radiation to bony metastases from GI tumors: Disparities, outcomes, and practice patterns
Authors: Hirshberg Jason , Hsu Charles , Robbins Jared 
Published: September 2020

Abstract
PURPOSE: To evaluate the use of palliative radiotherapy (pRT) for osseous metastases among patients with gastrointestinal malignancies by sociodemographic factors, tumor type, and survival.
METHODS: The NCDB was used to identify 9297 patients with GI cancers who received pRT to bony metastases from 2004 to 2013. Cancers assessed included esophageal, stomach, pancreatic, hepatocellular (HCC), bile duct & other, gallbladder, colon/sigmoid, and rectal. After excluding incomplete data, 5774 remained for analysis. Strata included age, race, sex, household income, Charlson-Deyo score (CDS), site of bony metastasis, Insurance status, treatment facility type, and distance from treatment site (crow-fly). Outcomes of interest included survival after diagnosis, survival after pRT, completion of pRT, and percent of remaining life spent receiving radiotherapy (PRLSRT). Chi-squared, Kaplan Meier curve with log rank analyses, and Cox Regression evaluated outcomes as a factor of sociodemographics.
RESULTS: Patients were 69% male, 81% Caucasian (CA) and 13% African American (AA). Pancreas, HCC, and Colon/Sigmoid cancers made up 63% of primary tumors. The most commonly used pRT regimen was 30Gy in 10 fractions, and single-fraction 8Gy was increasingly utilized towards 2013. As survival decreased, use of single-fraction pRT increased indicating appropriate pairing of treatment duration to prognosis. This trend was consistent among both AA and CA patients.
AA patients were younger and more likely to live &lt;20mi from their treatment facility compared to CA’s. AA’s were more likely to have no insurance or Medicaid (9.7% vs 5.3%, or 18.1% vs 8% p&lt;0.05), and have an annual household income below $30k (37.3 vs 11.4%) compared to CA’s. AA’s were less likely to have pancreatic cancer. Slightly more AA’s completed pRT than CA’s (69.2% vs 65.2%, p&lt;0.05), and had longer survival after diagnosis compared to CA (10.2 vs 9.7 months) but shorter survival after pRT suggesting a delay in palliation. Additionally, those who lived 40-60 miles from treatment facility had higher mean survival. Patients with private insurance and those treated at integrated network programs survival advantages.
PRLSRT did not differ by race, but decreased from 2004 to 2013. PRLSRT&gt;50% (p50) did not differ by crow-fly or facility type, but men and those with Medicare were more likely to have p50. A PRLSRT of 10% or less (p10) was more frequent in those who were treated at an academic facility, lived &gt;60mi away, had private insurance, a lower CDS, or earned $48-63k/yr in 2012. Sites with more p50 were the spine, skull, and spinal cord. Sites with higher p10 were extremity, shoulder, and ribs.
CONCLUSION: This study evaluated trends of pRT use among patients and stratified analyses by sociodemographic factors. Further research may uncover mechanisms of these trends and highlight potential strategies to optimize the use of pRT.
Citation Format: Jason Hirshberg, Charles Hsu, Jared Robbins. Palliative radiation to bony metastases from GI tumors: Disparities, outcomes, and practice patterns [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr C001.