Racial, Ethnic, and Socioeconomic Survival Disparities in Early-Onset Metastatic Colorectal Cancer.

[IMPORTANCE] Rates of metastatic colorectal cancer (mCRC) are rising among young adults. Disparities by race and ethnicity and neighborhood-level socioeconomic status (SES) among this population are understudied.

[OBJECTIVE] To examine the association of race and ethnicity and neighborhood-level SES with mortality among a community-based sample of young adults with mCRC.

[DESIGN, SETTING, AND PARTICIPANTS] This cohort study used a large electronic health record-derived database of young adults with cancer treated at 280 community-based US clinics between 2013 and 2021. Eligible patients were young adults aged 18 to 49 years diagnosed with de novo or recurrent mCRC. Patients were followed up until December 31, 2022. Data were analyzed from February 2024 to November 2025.

[EXPOSURES] Race and ethnicity and neighborhood-level SES. Neighborhood-level SES was derived using census block group (2010 Census boundaries) and most recent address in the electronic health record. Five-year estimates from the American Community Survey (2015-2019) were used to compute the Yost Index, a composite measure of 7 variables that capture different aspects of neighborhood-level SES.

[MAIN OUTCOME AND MEASURE] All-cause mortality and 1-, 2-, and 3-year survival from diagnosis. Survival was defined from date of de novo or recurrent mCRC diagnosis to date of death or December 31, 2022.

[RESULTS] A total of 3115 young adults diagnosed with mCRC (mean [SD] age at diagnosis, 42.4 [5.9] years; 122 Asian [3.9%], 424 Black [13.6%], 395 Hispanic [12.7%], 1874 White [60.2%]; 1651 male [53.0%]). Survival differed significantly by race and ethnicity and neighborhood-level SES. At 3 years after diagnosis, Black patients had worse survival (41%; 95% CI, 36%-46%), while Asian (58%; 95% CI, 48%-66%) and Hispanic (53%; 95% CI, 48%-58%) patients had better survival compared with White patients (47%; 95% CI, 45%-49%). For neighborhood-level SES, 3-year survival was 41% (95% CI, 36%-45%) for patients in the lowest compared with 59% (95% CI, 54%-63%) in the highest quintile. In adjusted analyses, neighborhood-level SES was associated with mortality (Q1 vs Q5: hazard ratio [HR], 1.51; 95% CI, 1.24-1.82), while the HR for Black race and mortality was greater than 1 but not statistically significant (HR, 1.08; 95% CI, 0.90-1.31).

[CONCLUSIONS] In this cohort study of young adults with mCRC, 3-year survival differed by race and ethnicity and neighborhood-level SES, but only the association between neighborhood-level SES and survival remained statistically significant after adjusting for covariates.