Urban/rural disparities in stage at presentation of colorectal cancer among young adults in the United States, 2007-2015.

Abstract

3598 Background: The overall incidence rate of colorectal cancer (CRC) has declined in recent decades but is rising in young adults (YA). Disparities also exist in CRC presentation and geographical residence. We examined associations between urban/rural residence and CRC stage at presentation among YA 18-50 years old, using the Surveillance, Epidemiology, and End Results (SEER) 1973-2015 registry. Methods: Retrospective cohort study using SEER patients (pts) diagnosed with CRC between 2007-2015, aged 18-50. Urban/rural status was defined at the county level as large metro, small metro, urban non-metro, and rural. Pts were grouped by age: 18-30, 31-40, and 41-50 years old. Stage was defined as in-situ/localized and regional/distant. We used multivariable logistic regression to describe associations between urban/rural status with stage at presentation, adjusting for tumor location, histology, grade, and patient attributes (e.g. insurance status). Results: 27,198 CRC pts were analyzed: 62.2% large metro, 27.4% small metro, 9.4% urban non-metro, and 67.1% regional/distant stage. In multivariable analysis, YA in urban non-metro counties had lower odds of regional/distant stage at presentation compared to YA in large metro counties (OR = 0.87, 95% CI = 0.79-0.97). Associations between small metro and rural status with stage at presentation were not significant (OR = 0.94, 95% CI = 0.89-1.01 and OR = 0.84, 95% CI = 0.64-1.10, respectively). YA with Medicaid or no insurance had higher odds of regional/distant CRC (OR = 1.28, 95% CI = 1.17-1.39 and OR = 1.34, 95% CI = 1.20-1.51, respectively) compared to YA privately insured. Other factors in YA associated with higher odds of regional/distant CRC included signet-ring histology, poorly-, moderately-, and undifferentiated grade, and younger age (18-30 and 31-40 years old). Conclusions: YA in urban non-metro areas had lower odds of regional/distant CRC at presentation compared to YA in large metro areas. YA with Medicaid, no insurance, signet-ring histology, poorly-, moderately-, and undifferentiated grade, and younger age had higher odds of regional/distant CRC at presentation. Further research is needed to explore the etiology of these differences.