Abstract D105: Differences in receipt of surgery contribute to survival disparities in esophageal and gastric cancers
Authors: Bliton John , Muscarella Peter , Parides Michael , Papalezova Katia , McAuliffe John , In Haejin 
Published: September 2020

Abstract
Introduction: Mortality disparities for gastrointestinal cancers are well described. Differences in rates of surgery across race and ethnicity may contribute to this phenomenon. In order to evaluate this, we assessed the extent to which the mortality disparity among racial/ethnic groups for gastrointestinal cancers are due to differences in operative rates. Methods: Data for patients with stage I-III esophageal and gastric cancer diagnoses between 2004-2015 were obtained from National Cancer Database. Cancers were categorized in 3 groups: mid-esophageal (ME) cancers, distal third of esophagus and cardia gastric cancers (DEC), and non-cardia gastric (NCG) cancers. Variables included demographics, receipt of surgery, tumor stage and characteristics, and hospital factors. The racial disparity in survival was measured as the hazard ratio (HR) for Black, Latinx, and Asian/Pacific Islander patients compared to White patients. A mediation analysis was performed to quantify the contribution of variables to the observed disparity between minority and White patients. The magnitude of the contributions was estimated using two methods: the change in HR with (1) the addition of each variable of interest to a model only adjusted by age and year, and (2) the removal of each variable from a multivariate model that included all variables. Factors associated with undergoing surgery were also examined using a logistic regression model. Results: A total of 124,862 patients were included (20,852 with ME, 74,427 with DEC, and 29,583 with NCG). Black patients were more likely to be from lower-income and urban areas and had lower operative rates in all cancers. The observed HRs for Black patients compared to White patients were 1.42 (95% CI 1.36-1.49) for ME, 1.36 (1.31-1.43) for DEC and 1.01 (0.97-1.05 – no observed disparity) for NCG tumors, adjusting for age and year of diagnosis. Only Black race/ethnicity was associated with a mortality disadvantage compared to White patients. Without adjustment for any additional variables, receipt of surgery accounted for more than half of the observed survival disparity for tumors of the esophagus and cardia (ΔHRs for ME: 0.27, DECS: 0.25 and NCG: 0.07). After adjustment for tumor, patient and hospital factors, receipt of surgery remained the single strongest contributor to the Black/White disparity in survival for all cancers (ΔHRs for ME: 0.070, DEC: 0.091 and NCG: 0.07). On logistic regression, Black patients were less likely to have received surgery after adjusting for other variables compared to White patients (ME aOR: 0.41 (0.37-0.46), DECS aOR: 0.42 (0.39-0.46), and NCG aOR: 0.79 (0.73-0.86)). Conclusions: Observed survival disparities in upper GI cancers may be due to fewer surgeries being performed for Black patients. Addressing differences in receipt of surgery for stage I through III esophageal and proximal stomach cancer has potential to mitigate cancer mortality disparities.
Citation Format: John Bliton, Peter Muscarella, Michael Parides, Katia Papalezova, John McAuliffe, Haejin In. Differences in receipt of surgery contribute to survival disparities in esophageal and gastric cancers [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 D105.