Exploring young-onset colorectal cancer sex difference incidence rates by race and ethnicity: A SEER database analysis (2000-2020).

e15529 Background: Since 1994, there has been a 51% increase in young onset colorectal cancer incidence rates, as reported by the National Cancer Institute. Recently, the U.S. Preventative Task Force revised its guidelines, recommending colorectal cancer screening to commence at age 45 rather than 50. This study aimed to explore sex differences in cancer incidence across various race and ethnicities, aiming to discern whether these differences are rooted in biological factors or environmental exposures. Methods: Cancer incidence data from the Surveillance, Epidemiology and End Result (SEER) program (2000-2020) was used to calculate male-to-female incidence rate ratios (MF IRR) for colon and rectal cancer, stratified by race and ethnicity (non-Hispanic White, non-Hispanic Black, non-Hispanic Asian/Pacific Islander, American Indian/Alaskan Native, and Hispanic), and age-standardized to the 2000 U.S. population for individuals under the age of 50 diagnosed with colon or rectal cancer. Results: A total of 82,238 patients with colorectal cancer under the age of 50 were identified in the study period. Of these, 43,255 (52.6%) were males and 38,983 (47.4%) were females. The incidence trends over the years were analyzed, revealing a steady increase, with the highest incidence found in 2019 (4,819, 5.8%) and the lowest in 2000 (3,189, 3.8%). Non-Hispanic Whites comprised 57.2% of the cases, while the second and third largest groups were Non-Hispanic Black (13.2%) and Hispanic (17.9%). Incidence rates were highest among the non-Hispanic American Indian/Alaskan Native population (8.6 per 100,000 cases), followed by the non-Hispanic Black population (8.4 per 100,000 cases), and lowest in the Hispanic population (5.7 per 100,000 cases). Young-onset colorectal cancer incidence rates exhibited a male predominance, with the MF IRR consistently > 1 every year across race and ethnicity. Non-Hispanic Asian/Pacific Islander had the highest MF IRRs (7 per 100,000 cases in males vs. 5.8 per 100,000 cases in females), while Non-Hispanic American Indian/Alaskan Native had the lowest MF IRRs throughout the years, with the lowest being in 2019 (5.1 per 100,000 cases in males vs. 12.6 per 100,000 cases in females). Conclusions: The MF IRR for young onset colorectal cancer showed no significant variation by race, implying a potential influence of biological factors. Notably, disparities in incidence rates were observed among different racial and ethnic groups, with the highest rates among non-Hispanic Black and non-Hispanic American Indian/Alaskan Native populations. Further research is warranted to pinpoint specific factors driving young onset colorectal cancer, facilitating targeted interventions for at-risk populations.