Abstract PO-168: Association between geography and cause-specific mortality in gastrointestinal cancers in Georgia
Authors: Nash Rebecca , Miller-Kleinhenz Jasmine M. , Russell Maria C. , Collin Lindsay J. , Ross-Driscoll Katherine , Switchenko Jeffrey M. , McCullough Lauren E. 
Published: December 2020

Background: Cancers of the gastrointestinal system represent a diverse range of diseases with different etiologies, from screening-detectable colorectal cancer (CRC) to pancreatic cancer, often diagnosed at late stage and highly lethal. While racial disparities have been observed for some of these cancers, the impact of geography is less understood. Georgia is an ideal place to examine disparities in geography because it has a diverse setting and population, with approximately 25% of residents living in a rural area and nearly one-third identifying as non-Hispanic Black (NHB), according to the 2010 decennial census. Methods: We obtained clinical (age at diagnosis, tumor stage, tumor size), sociodemographic (e.g., insurance status, marital status, SES index), and treatment information (e.g., receipt of surgery, lymph node biopsy/removal) on nearly 30,000 NHB and non-Hispanic White (NHW) men and women aged 18 years and older, diagnosed with CRC, hepatocellular carcinoma (HCC), pancreatic cancer or gastric cancer between 2009 and 2014 in Georgia from the population-based Surveillance, Epidemiology, and End Results (SEER) Program.

Patients were classified as residing in a metro or non-metro county at diagnosis according to 2013 rural-urban continuum codes. Multivariable Cox proportional hazards models were used to calculate the hazard ratios (HRs) and corresponding 95% confidence intervals (95% CI) for the association between residing in a non- metro versus metro county and cause-specific mortality, stratified by patient characteristics. Results: Over 75% of the study population resided in a metro county at diagnosis, with the highest proportion among HCC cases (81%) and the lowest proportion among CRC cases (76%). Overall, NHBs were more likely to reside in metro counties (82%) than NHWs (74%). The average length of follow-up varied by cancer site and metro status, ranging from 35 months (CRC in metro areas) to 4 months (pancreatic cancer in non-metro areas). For all cancer sites, patients in metro counties were more likely to be younger, single, have localized disease (except gastric cancer), and receive surgery of the primary site. By comparison, patients in non-metro counties were more likely to be diagnosed at older ages, have Medicaid, and be widowed. Residing in a non-metro county was associated with higher cause- specific mortality among the youngest patients (age 18-49 years) for pancreatic cancer (HR=1.4, 95% CI: 1.1, 1.9) and gastric cancer (HR=1.8, 95% CI: 1.2, 2.6). We also observed a higher hazard of mortality for residing in a non-metro compared to metro county among NHB HCC patients (HR=1.3, 95% CI: 1.0, 1.7) and never married gastric cancer patients (HR=1.5, 95% CI: 1.1, 2.1). Associations among CRC patients were less robust. Conclusion: Our results suggest residing in a non-metro county is associated with higher mortality among some groups diagnosed with rarer gastrointestinal cancers. Geographic differences in access to diagnosis and treatment may contribute to this disparity.

Citation Format: Rebecca Nash, Jasmine M. Miller-Kleinhenz, Maria C. Russell, Lindsay J. Collin, Katherine Ross-Driscoll, Jeffrey M. Switchenko, Lauren E. McCullough. Association between geography and cause-specific mortality in gastrointestinal cancers in Georgia [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-168.