Colorectal cancer in young patients below screening age - Demographic and socioeconomic factors associated with incidence and survival.

Background: While early onset colorectal cancer (EOCRC) has previously been defined as CRC in patients younger than age 50, recent screening guidelines have been lowered to 45. With more younger patients aged 45-50 are now being screened, incidence trend and outcomes of very early EOCRC (20-44) remains unclear.

Method: Surveillance, Epidemiology, and End Results database was analyzed between 2006 and 2016 using Joinpoint tool to evaluate annual percentage change (APC) in incident rates, focusing on race/ethnicity and socioeconomic status (SES). Cancer specific survival (CSS) was assessed using univariate and multivariate analysis.

Results: 41,815 EOCRC patients met inclusion criteria. Incidence has increased significantly in both age groups (APC in age group 20-44 = 1.21 and 45-49 = 1.06). Increase incidence of very early EOCRC was observed in White and Hispanic racial/ethnic groups (ACP 1.68 and 2.63), as well as population from counties with high poverty, unemployment, language barrier, foreign born resident, and high school dropout rates (ACP 2.07, 1.87, 1.21, 1.28 and 2.02 respectively). Further, the 5-year CSS was worse in Black patients, and patients from counties with high poverty, unemployment and high school dropouts rates (Age group 20-44, 63.11%, 66.39%, 67.48% and 66.95% respectively). On multivariate analysis, living in high poverty counties was an independent risk factor for poorer CSS for very early EOCRC (HR 1.20, 95% CI 1.07-1.34, p = 0.002). Multivariate analysis was adjusted by sex, pathology type, site of disease, disease extension and surgical treatment history.

Conclusion: Very early EOCRC incidence increases in White, Hispanic and poor patients, and outcomes are worse for minority and low-income patients. Further study on very early EOCRC is needed among those patients.