Rectal Cancer Disparities Among the American Indian/Alaskan Native Populations

Recent work noted lower overall survival (OS) in American Indian/Alaskan Native (AI/AN) individuals diagnosed with colon cancer compared with non-Hispanic White (NHW) individuals. Rectal cancer demographic profiles at diagnosis and survival outcomes have not been reported. We sought to identify differences in rectal cancer diagnosis and outcomes between AI/AN and White populations.

White and AI/AN patients aged 18 or older, diagnosed between 2004 and 2020 with rectal adenocarcinoma were identified within the National Cancer Database (NCDB). Unadjusted and adjusted analyses were used to evaluate demographic and clinical standardized differences (stddiff) between AI/AN and White patients. Survival analyses of those diagnosed with locally advanced rectal cancer (Stage II/III) were performed using the Kaplan-Meier methods and multivariate Cox-proportional hazards modeling.

176,341 eligible cases were identified: 0.6% were AI/AN (N = 992) and 99.4% White (N = 175,349). Compared to the White population, AI/AN patients were younger at diagnosis (mean age 59.9 vs. 64.5 years; stddiff = 0.36) and had more advanced stage disease (44.8% vs. 43.7%; stddiff = 0.15). A higher percentage of AI/AN resided in the areas of the lowest median income (35.5% vs. 15.1%; stddiff = 0.62) per zip code, rural (9.9% vs. 2.2%; stddiff = 0.65), and used Medicaid as their primary payor (14.3% vs. 6.2%; stddiff = 0.63). Adjusted analyses suggest the AI/AN group has an increased hazard of death compared with the White population (HR, 1.14; 95% CI, 1.05-1.25; p = 0.003).

AI/AN patients with rectal cancer have a younger age and a more advanced stage at diagnosis. AI/AN race is associated with lower OS compared to White patients in multivariable analyses. Future efforts should focus on increasing colorectal cancer screening and access to treatment for AI/AN populations in an attempt to improve survival outcomes.