S606 Increasing Colorectal Cancer Incidence in Young Adults: A SEER Analysis

Introduction: Overall colorectal cancer incidence has declined among adults, but incidence among those younger than 45 years has been increasing. In this study, we aim to investigate the trend of rising colorectal cancer incidence in younger adults, along with associated factors. Methods: We used data from the Surveillance, Epidemiology, and End Results (SEER) 8 registries from 1975 through 2022. We first examined trends in age-adjusted incidence rates per 100,000 people for all ages and for adults under 45. Within the under-45 age group, we conducted additional analyses by sex, race, and tumor location. Results: Over the past 5 decades, the overall incidence of colorectal cancer has declined steadily. However, among adults under 45, incidence trends have been increasing since the 1990s in both men and women and across all racial groups. Specifically, incidence in the sigmoid colon and rectum has increased among younger White individuals and those of other races. Among younger Black individuals, incidence of rectal cancer has increased. Notably, since 2010s, the incidence of appendiceal cancer has sharply increased across all racial groups. Conclusion: The United States Preventive Services Task Force recently lowered the recommended colorectal cancer screening age to 45. However, our study confirms that incidence among young adults has continued to rise, with particularly high increases in certain racial groups and at specific tumor sites. These findings underscore the need for careful attention to early-onset colorectal cancer.