Abstract B099: Rural black cases have worsened outcomes in head and neck cancer
Authors: Clarke Jacob A , Despotis Alyssa M , Zevallos Jose P , Mazul Angela L 
Published: September 2020

Abstract
Background: Racial and socioeconomic disparities in head and neck cancer survival are well documented. However, rural-urban context, especially the interaction between race and rural-urban context, is understudied. The aim of this study is to examine the relationship between race and rural-urban context in HNC survival and determine factors that potentially drive this disparity.
Methods: We constructed a retrospective cohort of 158,718 head and neck squamous cell cases from the National Cancer Database with the following sites: hypopharynx (9.54%), larynx (54.42%), and oral cavity (36.04%). Since we are interested in traditional head and neck cancer, oropharyngeal cases were excluded from the cohort. We used Rural-Urban Continuum Codes (RUCC) to classify cases into metro (RUCC 1-3) and non-metro subgroups (RUCC 4- 9). Risk factors were classified into demographic (age and gender), socioeconomic (insurance status), and clinical factors (site, stage, and treatment modality). Kaplan-Meier survival curves and the Cox proportional hazards regression were used to calculate adjusted hazard ratios (HR). The proportional hazards and linearity assumptions were tested and satisfied.
Results: The exposure cohorts that were analyzed include black metro (N = 17,256; 10.87%), black non-metro (N = 2,501; 1.57%), white metro (N = 109,842; 69.21%), and white-non-metro cases (N = 29,119; 18.35%). Rural-urban five-year survival differences are larger between black non-metro cases (39.32%; 95% Confidence Interval (CI): 37.21-41.56%) and black metro cases (43.97%; 95% CI: 43.15-44.81%) compared with white non-metro cases (50.32%; 95% CI: 49.68-50.99%) and white metro cases (53.12%; 95% CI: 52.79-53.45%). In the univariable Cox proportional hazards analysis, compared with white metro cases, black non-metro cases have the worst survival (HR: 1.44; 95% CI: 1.36-1.15; p&lt;.001) followed by black metro cases (HR: 1.28; 95% CI: 1.26-1.31; p&lt;.001) and white non-metro cases (HR: 1.0,76 95% CI: 1.06-1.10; p&lt;.001). Interestingly, there is no interaction between race and rural-urban context (p=0.18). After conducting a multivariable analysis controlling for demographic, socioeconomic, and clinical factors, the HRs were attenuated, but black non-metro cases continue to have worse survival compared with white metro cases.
Conclusion: Although there is no interaction between rural-urban context and race, black HNC cases, specifically those living in non-metro areas, have worse survival. This disparity still remains after adjusting for insurance status, site, and stage. Further research should be conducted to determine other modifiable risk factors to mitigate this racial and geospatial disparity.
Citation Format: Jacob A Clarke, Alyssa M Despotis, Jose P Zevallos, Angela L Mazul. Rural black cases have worsened outcomes in head and neck cancer [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 B099.