Purpose: Early-onset colorectal cancer (EOCRC), defined as CRC diagnosed before age 50 years, has increased significantly worldwide. The majority of EOCRCs do not appear to be driven by genetic factors and may be influenced by environmental factors. We hypothesized that sociodemographic disparities exist in EOCRC. The purpose was of the study was to examine the geographic disparities in patients with EOCRC.
Methods: We retrospectively examined the SEER database from 1976 to 2016 to examine the geographic disparities in EOCRC. A total of 73,378 patients with EOCRC were included in the analysis. We performed univariate and multivariable analyses to evaluate overall survival (OS) and disease-specific survival (DSS). Sociodemographic factors, including the location of residence (metropolitan areas [MA] or rural areas [RA]), sex, race, insurance status, and marital status, were included in the statistical analysis.
Results: The incidence and mortality rates were consistently higher in RA versus MA during the study period. Multivariable analysis showed that patients living in RA had worse OS (hazard ratio [HR], 1.14; P < .01) and DSS (HR, 1.15; P < .001) compared with those living in MA. Similarly, non-Hispanic Black ethnicity and uninsured patients had significantly worse survival when compared with non-Hispanic White and insured patients, respectively. Married status showed better survival outcomes.
Conclusion: Patients with EOCRC living in RA have worse outcomes. Understanding the mechanisms behind such socioeconomic disparities is important so that future studies can reduce these disparities.