Abstract PO-223: Racial disparities in early- and late-onset colorectal cancer incidence, 2001- 2016

Background. Colorectal cancer (CRC) incidence rates have increased in younger individuals worldwide. A recent US study reported increases among both non- Hispanic whites (NHW) and non-Hispanic blacks (NHB), but did not consider other racial/ethnic groups. Thus, we examined the most recent CRC rates for the US by age, race/ethnicity, and anatomic location. Methods. Age-standardized incidence rates (ASR, per 100,000) of CRC were calculated for 2001-2002 through 2015-2016 using the US Cancer Statistics Database, which includes data from the National Program of Cancer Registries and the Surveillance, Epidemiology, and End Results Program. US Cancer Statistics covers the entire US population. Results were cross- classified by age (20-49 [early-onset] and 50-74 years [late-onset]), race/ethnicity (NHW, NHB, Hispanic, American Indian/Alaskan Native [AIAN], Asian/Pacific Islander [API]), and location (proximal, distal, rectal). To examine the change in ASR over time, annual percent change (APC) was calculated using joinpoint regression models. Results. Historically, NHB have had the highest rates of early-onset CRC. However, in 2015-2016, early-onset CRC rates were highest in AIAN (ASR=14.72), followed by NHB (ASR=13.20) and NHW (ASR=12.31). The rate of early-onset proximal colon cancer was highest in NHB (ASR=4.83), which was 62% higher than the rate in NHW (ASR=2.98). Early-onset distal colon and rectal cancer rates were highest in AIAN (ASR=3.98 and 6.43, respectively). Between 2001-2002 and 2015-2016, early-onset CRC rates significantly increased among NHWs (APC=1.62%) and AIAN (APC=3.33%). Racial disparities in incidence of early-onset CRC have decreased between NHB and NHW, due to increasing rates in NHW. Among NHW, early-onset CRC has significantly increased for all CRC locations, with the largest increase for rectal cancer (APC=2.22%). Early-onset rates of rectal cancer also significantly increased for AIAN (APC=4.38%) and Hispanics (APC=0.76%), while rates of proximal colon cancer significantly increased for AIAN (APC=2.21%). Rates of late-onset CRC have significantly decreased in all racial/ethnic groups. However, compared to NHW (ASR=82.48), late-onset CRC rates remain 32% higher in NHB (ASR=108.91) and 18% higher in AIAN (ASR=97.06). Conclusion. Early-onset CRC rates have been increasing, while late-onset CRC rates have decreased. The racial disparity between NHB and NHW in incidence of early-onset CRC has decreased, but this is due to increases in NHW—not decreases in NHB. NHB and AIAN have the highest rates of both early-and late-onset CRC. To counter these trends, research should focus on identifying predictors of early-onset CRC to determine who should be screened prior to age 50 and identify underlying causes of early-onset CRC. Further, ongoing prevention efforts must ensure access to screening colonoscopies for AIAN and NHB. Citation Format: Jessica L. Petrick, Lauren E. Barber, Shaneda Warren Andersen, Andrea A. Florio, Julie R. Palmer, Lynn Rosenberg. Racial disparities in early- and late-onset colorectal cancer incidence, 2001- 2016 [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-223.