Early onset colorectal cancer (EOCRC) has been increasing at an alarming rate in the United States [1]. While the incidence rate of colorectal cancer (CRC) in older adults is decreasing, incidence rates for younger adults (age <50 years) in the United States have doubled since the early 1990s. Moreover, with current increase trend, more than 15% of CRCs will be diagnosed in younger adults by 2030 [2]. In May 2021, the U.S. Preventive Services Task Force (USPSTF) lowered colorectal cancer (CRC) screening age from age 50 to 45 for the average risk population, which also redefined the unscreened population [3]. Previous studies in EOCRC incidence and outcome didn't reflect this change in age threshold, and an updated study with attention to the age group below and above 45 years is needed [[4], [5], [6]].

Furthermore, compared with normal age onset CRC, EOCRC differs in clinical, pathological, and molecular presentation [7,8], and the majority of EOCRC is sporadic [7]. The etiology for EOCRC's up-trending incidence has been a hot research field. Lifestyle risk factors and limited access to medical care have been analyzed as potential risk factors [9,10], and those factors were also related to both EOCRC and low socioeconomic status (SES) [[9], [10], [11]]. Previous studies also found difference in EOCRC outcomes among patients with different racial, cultural, and geographic background in the US [[12], [13], [14], [15]]. Those suggested SES factors' association with racial/ethnic and SES factors with EOCRC. However, those previous works described either incidence or outcomes of EOCRC, and only a few racial or SES factors were involved. In this context, a comprehensive analysis of EOCRC's characteristics in different racial and SES population is needed, especially with the updated USPSTF screening age.

Therefore, this study aims to comparatively investigate the association between racial/ethnic factors and SES backgrounds with EOCRC. Hence, we performed a dedicated analysis in patients younger than 45 (20–45, unscreened) and older than 45 (45–49, screened).