Racial Trends in Appendiceal Adenocarcinoma Incidence in the United States: A SEER- Based Analysis (2000–2022)

Appendiceal adenocarcinoma is a rare gastrointestinal malignancy with increasing recognition due to improved imaging and surgical pathology. Despite this, racial and ethnic disparities in incidence and outcomes remain poorly described due to limited population-level data. Understanding racial trends over time can provide insight into evolving diagnostic patterns and healthcare access.

To evaluate racial disparities and temporal trends in appendiceal adenocarcinoma incidence in the United States using SEER population-based data from 2000 to 2022.

Data were extracted from the SEER 8 Registries (Nov 2024 submission; 1975–2022) using SEER*Stat v8.4.x. Eligible cases included appendiceal adenocarcinoma (Primary Site: C18.1; ICD-O-3 histology codes 8140/3, 8480/3, 8481/3, 8490/3) diagnosed between 2000 and 2022. Incidence frequencies were stratified by the SEER Race recode (White, Black, Other) variable and analyzed over time. Annual frequencies and proportions were visualized to assess incidence trends among racial groups.

A total of 7,473 cases of appendiceal adenocarcinoma were identified between 2000 and 2022. The racial distribution was as follows: 6,137 (82.1%) cases occurred in White patients, 558 (7.5%) in Black patients, and 662 (8.9%) in the Other racial group (American Indian/AK Native, Asian/Pacific Islander); 116 (1.6%) cases were of unknown race. A profound increase in annual incidence was observed across all groups, with the total number of cases rising from 99 in 2000 to 710 in 2022. This upward trend accelerated after 2010. The "Other" racial group demonstrated the most significant relative growth, with annual cases increasing over 1,300%, from 6 in 2000 to 85 in 2022, a rate of increase that far exceeded that of White and Black patients.

The incidence of appendiceal adenocarcinoma has steadily increased in the U.S. across all racial groups over the past two decades. While White patients remain the most frequently diagnosed group, the dramatic relative increase among the "Other" racial category suggests evolving diagnostic patterns, demographic shifts, and potentially improved healthcare access and reporting for these populations. Further studies should assess whether racial disparities extend to treatment patterns and survival outcomes.