Abstract

Colorectal cancer (CRC) is one of the four most common cancers and the third leading cause of cancer-related deaths in Guam. This study investigated CRC incidence, screening, and risk factors of early onset CRC across Guam's ethnic groups using data from the Guam Cancer Registry (1998–2020) and the Guam Behavioral Risk Factor Surveillance System (2018–2019). Incidence rate ratios (IRRs) were calculated to compare incidence rates across different age groups stratified by sex, ethnicity, and stage. Incidence rate differences (IRDs) were used to test for significant differences across sex and ethnicity. The Pearson chi-square test was used to assess differences in CRC screening rates by age, sex, education, income, healthcare coverage, and ethnicity, and to examine ethnic group disparities in the prevalence of CRC risk factors. The steepest increase in CRC incidence was observed between the 35–39 and 40–44 age groups (IRR = 2.01; 95 % CI: 1.14–3.53) and between the 40–44 and 45–49 age groups (IRR = 1.99; 95 % CI: 1.34–2.97). CHamorus exhibited rate increases at younger ages compared to Filipinos. CRC screening prevalence and associated risk factors showed considerable variation among ethnicities. Elevated early-onset CRC rates were observed for both CHamorus and the broader Guam population under 50. The findings support the new recommendation to begin screening at age 45 and efforts to increase screening in Guam.