Abstract PO-172: The impact of environmental quality on colorectal cancer incidence rates in the United States
Authors: Li Tingting , Hsieh Mei-Chin , McDaniel Lee S. , Peters Edward S. 
Published: January 2022

Abstract
Background Colorectal Cancer (CRC) is the third most common cancer and the third leading cause of cancer-related deaths in the US. CRC has been shown to be an environmentally associated disease, and the identification of specific environmental risk factors is critical to identify intervention opportunities in high-risk populations. CRC incidence rates have been increasing among people living in rural areas compared to non-rural. Understanding the relationship between environmental factors and rurality on CRC incidence is imperative to improve CRC prevention and control efforts. We used the Environmental Quality Index (EQI) developed by the US Environmental Protection Agency (EPA) to represent multiple simultaneous environmental domains to measure of the overall environment and examined its association with CRC incidence rates in the US. Methods The 2006-2010 EQI, a county-level index including overall and five specific domains (air, water, land, sociodemographic (SD), and build) for the entire US, was obtained from the US EPA public database. Data for the 2013-2017 county-level age-adjusted CRC incidence rates were extracted from the State Cancer Profiles and linked to the EQI data using the Federal information processing standard (FIPS) state-county code. EQI was categorized into Quintiles (Q1 represents highest environmental quality and Q5 represent poorest environmental quality). Pearson's correlation and linear regression were used to test associations between CRC incidence rate and EQI. Covariates included rural/urban status, percent of Black or African Americans (AAs), and state. Incidence rate differences (IRDs) and 95% confidence intervals (95%CI) were reported. Results Correlations between CRC incidence and EQIs were observed positive in overall (r = -0.06; Р =0.002) and domains including air (r = 0.01; Р = 0.66), build (r = 0.01; Р = 0.67), land (r = 0.08; Р &lt;0.001), SD (r = 0.45; Р &lt; 0.001), and negative in build domain (r = -0.12; Р &lt; 0.001). In the adjusted model, for the SD domain, those counties with lowest quality quintile were associated with an incidence rate increase of 10.26 (8.87, 11.65) cases per 100,000 persons per year compared to counties in the highest quintile. The lowest build EQI (5th quintile) had 1.49 fewer cases per 100,000 persons per year comparing to the 1st quintile. About 82.5% of the observed elevation 7.7 (6.55, 8.84) in CRC incidence rates among rural counties, compared to metropolitan urbanized counties, were explained by the EQI and the percent of Black or AAs residing in the counties. Conclusion The EQI was observed to be a significant factor for increased CRC incidence, although its impact varied when examined by domains. The lowest sociodemographic quality had the strongest association with CRC, followed by highest build environmental quality. Further, sociodemographic disadvantage was found to be a robust predictor and largely explained the rural-urban CRC incidence disparity. Our study provides a broader view of the environmental quality effect on the CRC incidence disparities in rural areas.
Citation Format: Tingting Li, Mei-Chin Hsieh, Lee S. McDaniel, Edward S. Peters. The impact of environmental quality on colorectal cancer incidence rates in the United States [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-172.