A population-based study on incidence trends of small intestine cancer in the United States from 2000 to 2020

Background Although rare, small intestine cancer is on the rise in the developed world. We aimed to investigate the incidence trends of small intestine cancer by sex, race/ethnicity, age, and histological subgroups in the United States (US) over 2000-2020. Also, we evaluated the COVID-19 impacts on the incidence trends of this cancer.Methods Data were collected from the Surveillance, Epidemiology, and End Results 22 database. Both the average annual percent change (AAPC) and age-standardized incidence rates (ASIRs) were determined. The findings were expressed as counts and incidence rates adjusted for age per 100,000 people with 95% confidence intervals (CIs).Results A total of 67,815 cases of small intestine cancer across all age groups were reported in the US between 2000 and 2019. Neuroendocrine carcinoma was the most often reported subtype (54.26%). The age group of 55 to 69 years (38.08%), men (53.10%), and Non-Hispanic Whites (69.07%) accounted for the majority of cases. Over 2000-2019, the ASIRs for small intestine cancer among men and women were 2.61 (95% CI: 2.59-2.64) and 1.92 (95% CI: 1.89-1.94) per 100,000, indicating a significant increase of 2.01% and 2.12%, respectively. Non-Hispanic Black men had the highest ASIR (4.25 per 100,000). Also, those aged 80-84 age group had the highest ASIR. During COVID-19, the ASIR of small intestine cancer decreased by 8.94% (5.06-12.81%).Conclusions Small intestine cancer incidence raised in all sexes and ethnicities. Following COVID-19, reported cases declined, possibly due to pandemic-related diagnostic challenges. The impact of underdiagnosis on patient survival needs further investigations.