Association between environmental quality index and young onset colorectal cancer.

Abstract

75 Background: The factors associated with the rise of young-onset colorectal cancer (YOCRC) remain unclear. In addition to hereditary factors, environmental exposures are believed to be associated with YOCRC. Therefore, we aimed to study the association between the national level Environmental Quality Index (EQI) and YOCRC in the US. Methods: We used the SEER database to select the CRC patients diagnosed between 2010-2016. YOCRC was defined based on age at diagnosis < 50 years. EQI (2005-2010) is a measure of county-level cumulative environmental exposures that includes 5 domains: sociodemographic, built, air, land, and water. A higher value represents a lower environmental quality. We distributed the total EQI and each EQI domain into five quintiles. Multivariable logistic regression analysis was used to assess the relationship between YOCRC and quintiles (upper-most vs. lowest) of EQI after adjusting by race (White, Black, and Others), gender, and stage at diagnosis. The age-adjusted incidence rate was also calculated using the SEER*Stat, and correlation efficiency was estimated between EQI domains and incidence rate. Results: A total of 261,417 CRC patients were included; 11% were YOCRC. In the adjusted multivariable analysis, poor built EQI (OR 1.15 [1.11-1.20]) and water EQI (OR 1.08 [1.03-1.12]) were more likely to be associated with YOCRC. Poor built EQI was more strongly associated with Black YOCRC (OR 1.21 [1.09-1.35]) as compared to White YOCRC (OR 1.14 [1.09-1.19]). Poor sociodemographic EQI was more strongly associated with Others (OR 1.47 [1.25-1.72]) compared to Black YOCRC (OR 1.14 [1.03-1.25]). In addition, poor built EQI (OR 1.19 [1.12-1.27]) and water EQI (OR 1.12 [1.05-1.19]) were more strongly associated with the metastatic disease among YOCRC patients. However, the total poor EQI was not associated with YOCRC (OR 0.99 [0.95-1.03]). On incidence analysis, there was a positive correlation between the incidence rate of YOCRC and sociodemographic EQI (rho=0.49, p<0.001), air EQI (rho=0.30, p<0.001), and land EQI (rho=0.18, p<0.001). Conclusions: This study evaluated a population-based ecological approach and showed that YOCRC was associated with lower environmental quality, including built and water domains. EQI domains were also associated with different racial groups among YOCRC. [Table: see text]