Trend analysis of risk factors for early-onset primary colorectal cancer: A population-based time trend analysis using the SEER database.

e15717 Background: Colorectal cancer (CRC) is the third most common cancer worldwide and the second leading cause of cancer-related deaths. The incidence of early-onset CRC in individuals below 50 years old has been increasing. This contrasts with the declining incidence of late-onset CRC in individuals above 50, likely due to improved early screening. This study aims to investigate the association between CRC and potential risk factors that may contribute to the rising incidence of early-onset CRC. Methods: A time-trend analysis was conducted using data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database from 2000–2021. Age-adjusted incidence rates were calculated and compared across patient characteristics, including age ( < 50 years), sex, race/ethnicity, year of diagnosis, age at diagnosis, and urban-rural setting. Rates are reported per 100,000 population, with 95% confidence intervals. Percent changes (PC) were calculated using the first and last years of the study period, and annual percent changes (APC) were calculated using weighted least squares regression, with statistical significance set at p < 0.05. Results: Over the past two decades, there has been an increase in the overall incidence of CRC by 2.1-fold, from 2000 (9.8 per 100,000) to 2021 (15.2 per 100,000). Rates in females increased 2.3-fold and 1.9-fold in males. The largest rise was 6.5-fold in the 20–24 age group versus 1.4-fold in the 45–49 age group. By race/ethnicity, increases were greatest in American Indians (3.6-fold), non-Hispanic whites (2.5-fold), and Hispanics (2.8-fold), versus smaller increases in non-Hispanic blacks (0.9-fold) and Asians (0.5-fold). Patients residing in metropolitan areas with populations over 250,000 experienced a 2.3-fold increase in CRC incidence. Conclusions: SEER population-based data indicates that CRC incidence rates have increased over the past two decades among both genders and may continue to increase. We observed a potentially alarming trend in the increasing incidence in the young 20-24 age group, with a 6.5-fold rise. Future studies should investigate these findings, understand the underlying contributing factors, and determine the necessary actions to address these alarming trends.