Abstract 6135: Racial and ethnic differences in site of de novo metastases in patients with colorectal cancer: A SEER analysis
Authors: Loroña Nicole C. , Stern Mariana C. , Schmit Stephanie L. , Figueiredo Jane C. 
Published: March 2024

Abstract
Purpose: Disparities in colorectal cancer (CRC) mortality may be driven by differences in access to care, tumor biology, and propensity to spread to distant sites. We examine differences in patterns of de novo metastases by race/ethnicity and age.
Methods: We identified 248,732 CRC patients listed in the Surveillance, Epidemiology, and End Results (SEER) database diagnosed with a first primary invasive CRC from 2010-2020, aged 20+ years at diagnosis, with complete data on SEER summary stage, and not diagnosed only by autopsy/death certificate. Outcomes included de novo metastatic site (no metastasis, liver, lung, brain, bone) and pattern (no metastasis, liver only, lung only, liver and lung, other). We used logistic regression to calculate odds ratios (OR) and 95% confidence intervals (95% CI) for the associations between 1) demographic and tumor characteristics (site, side, T stage, N stage) and site of de novo metastases , and 2) race/ethnicity and site of de novo metastases stratified by age (20-49, 50-74, 75+). We used multinomial logistic regression to assess the association between demographic and tumor characteristics and pattern of metastasis. Models adjusted for age, race/ethnicity, sex, site (colon, rectum), side (left, right), T stage, and N stage.
Results: 62,844 stage IV CRC cases were diagnosed from 2010-2020, and liver was the most common metastatic site (72%). Relative to age 50-74, age 20-49 at diagnosis was more strongly associated with de novo liver metastases (OR: 1.07; 95% CI: 1.02-1.11) and less with lung (OR: 0.86; 95% CI: 0.80-0.92) or brain (OR: 0.69; 95% CI: 0.52-0.93) metastases. Relative to Non-Hispanic White (NHW) patients, Non-Hispanic American Indian/Alaskan Native (AI/AN) patients had a higher risk of lung metastases (OR: 1.33; 95% CI: 1.07-1.65), Non-Hispanic Asian/Pacific Islander (API) patients had lower risks of liver (OR: 0.87; 95% CI: 0.83-0.92) and brain (OR: 0.67; 95% CI: 0.48-0.95) metastases, and Non-Hispanic Black (NHB) patients had higher risks of liver (OR: 1.35; 95% CI: 1.29-1.41), lung (OR: 1.36; 95% CI: 1.27-1.45), and bone (OR: 1.23; 95% CI: 1.08-1.41) metastases. In age-stratified analyses, the risks for NHB patients persisted across groups, while lower risks for API patients were not observed in the 20-49 group. API patients aged 20-49 had a higher risk of de novo lung (OR: 1.31; 95% CI: 1.06-1.61) and bone (OR: 1.63; 95% CI: 1.13-2.37) metastases, and the increased risk of lung metastases for AI/AN patients was larger in magnitude (OR: 2.26; 95% CI: 1.39-3.68). Age 20-49 was more strongly associated with a liver-only pattern (OR: 1.14; 95% CI: 1.09-1.19) and with less common distant sites (OR: 1.33; 95% CI: 1.25-1.41).
Conclusions: Racial/ethnic differences in de novo metastatic CRC patterns exist overall and across age groups. These findings are consistent with disparities in risk of stage IV CRC and can inform surveillance priorities in CRC survivors.
Citation Format: Nicole C. Loroña, Mariana C. Stern, Stephanie L. Schmit, Jane C. Figueiredo. Racial and ethnic differences in site of de novo metastases in patients with colorectal cancer: A SEER analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6135.